Reverse Dieting: Hype Versus Evidence

Reverse dieting is often touted as a remedy for metabolic adaptation and a strategy to facilitate easier and more sustainable weight loss. However, this popular approach was originally driven by industry marketing rather than scientific evidence. This article will explore the actual research related to reverse dieting, which tells a much different story than the hyped-up anecdotes you’ll see on social media. It will also explain why reverse dieting often appears to work in the short term while falling flat in the long term, and why “dynamic maintenance” is a more flexible and less tedious strategy that offers every single benefit that reverse dieting actually delivers.

While diets take many different forms and target many different goals, the verb “dieting” most commonly implies the pursuit of weight loss. The typical “dieting process” progresses as follows:

1. You reduce calorie intake to establish an energy deficit (a state of negative energy balance, in which total daily energy expenditure [TDEE] is greater than total daily energy intake)
   
2. Due to the presence of an energy deficit, you lose weight
   
3. TDEE goes down for two reasons. First, smaller bodies have less metabolically active tissue and burn less energy. Second, we experience adaptive reductions in TDEE that aim to conserve energy. This is known as metabolic adaptation, and it’s primarily driven by reductions in a hormone called leptin. These leptin reductions are caused by the loss of fat mass and the presence of an energy deficit
   
4. Reduced TDEE is far from the only adaptation we experience during weight loss. Dieters may also experience some symptoms of relative energy deficiency, which are summarized in Figure 1
   
5. Due to the drop in TDEE, the energy deficit shrinks, and weight loss slows down or stops entirely
   
6. You reduce calorie intake even more to re-establish an energy deficit, and this cyclical process repeats until the weight loss goal is reached

With a summary like that, weight loss sounds like a breeze. However, I’ve presented the hyper-optimistic version of this sequence of events. In some cases, items #1 and #2 never occur, as it’s often difficult to identify the appropriate dietary targets and implement the necessary behavioral modifications to get weight loss rolling in the first place. 

However, for this article, I want to focus on items #3-5. It’s not unusual to encounter dieters in the following predicament:

• Initially, they achieved substantial progress toward their weight loss goal
• Eventually, total daily energy expenditure dropped, and weight loss started to slow down
• To make matters worse, they started feeling hungrier and more lethargic, while their slowing rate of progress simultaneously chipped away their motivation and self-efficacy
• If they were dieting quite aggressively (or had gotten quite lean), they might have also noticed some symptoms associated with relative energy deficiency (for example, lower thyroid hormone levels, lower sex hormone levels, lower libido, or menstrual cycle disruption)
• They know that lowering their calorie target is the solution to get weight loss rolling again, but their calorie target is already difficult to sustain, and they’re worried about exacerbating the unfavorable adaptations and side effects they’ve been observing by reducing calories even further

Reverse dieting emerged (in the fitness industry, not the research world) as a proposed solution to this common predicament. The general concept is implied by the name: rather than engaging in the typical dieting process of reducing calories as TDEE drops over time, you engage in an ongoing process of increasing calories over time, in hopes of increasing TDEE over time (or, more specifically, reversing the adaptive reductions in TDEE caused by dieting). That sounds pretty nice, so you’re probably wondering if it works. However, before we jump straight to conclusions, we should briefly discuss why proponents think it should work.

The Theoretical Case for Reverse Dieting

Reverse dieting is framed as a “solution,” so let’s start with the problem. As noted previously, dieting induces a number of physiological adaptations. Some of these adaptations directly oppose our weight loss goals; for example, a drop in TDEE means we have to lean on larger reductions in calorie intake or larger amounts of exercise to induce further weight loss. Other adaptations are quite unpleasant, such as increased hunger, decreased energy levels, and lower libido. Many dieters experience this cluster of adaptations at some point in a diet, but these adaptations are particularly pronounced among bodybuilders and other physique athletes. Notably, these individuals tend to approach dieting cyclically – they get extremely lean for competitions (which often requires the use of aggressive weight loss strategies), then they regain weight and recover after competitions. Gaining weight (largely as fat mass) after competitions facilitates recovery and reverses the unpleasant adaptations induced by weight loss. However, physique athletes typically aren’t fond of gaining fat, and precipitous post-diet fat gain could potentially make their next fat loss phase more of an uphill battle. 

With this in mind, reverse dieting emerged as a theoretical strategy that might allow physique athletes to have the best of both worlds – post-competition recovery and cessation of unpleasant weight loss adaptations, without such rapid fat regain. The theoretical case for reverse dieting is threefold. First, it’s clear that metabolic adaptation is driven by the loss of fat mass, but is also independently driven by the presence of an energy deficit. The first applications of reverse dieting sought to keep fat mass pretty low, while focusing on methodically transitioning from an energy deficit (negative energy balance) to maintenance calories (neutral energy balance), or even to a very small energy surplus (positive energy balance). The idea is that the gradual transition out of an energy deficit will promote “recovery” from the previous diet and reverse many of the adaptations associated with dieting, without regaining an appreciable amount of fat mass. Second, there is evidence to suggest that TDEE tends to increase during overfeeding, while evidence also suggests that people are highly susceptible to fat regain after intentional weight loss. The slow and methodical approach of reverse dieting, characterized by small, gradual increases in calorie intake (often accompanied by gradual reductions in cardio) seeks to attain the TDEE boost induced by slightly positive energy balance, while avoiding a large, abrupt increase in calories that could promote rapid fat regain. The third element of the justification is an extension of the first two. Rather than retaining a suppressed metabolic rate or precipitously gaining fat after a diet, the reverse dieter aims to boost their TDEE while staying lean. This is thought to confer some theoretical advantages for their next fat loss phase – they have less total fat to lose next time around, and their higher TDEE would (purportedly) allow them to successfully diet with higher daily calorie targets. 

Common Claims About Reverse Dieting

With this theoretical rationale in mind, people often make the following claims about reverse dieting:

• It “fixes” a “damaged” metabolic rate, which is what’s currently making it nearly impossible for you to lose more weight (or virtually guaranteeing that you’ll promptly regain all of the weight you’ve lost so far)
• It “fixes” unfavorable hormone changes observed during weight loss, in the absence of fat regain
• It supercharges an individual’s metabolic rate beyond the level that is typically normal for them
• It makes subsequent weight loss attempts easier or more successful (due to the previously mentioned effects on hormone levels and metabolic rate)

To be clear, I suspect that the vast majority of reverse dieting proponents make these claims with good intentions and genuinely believe them to be truthful and accurate. However, the scientific evidence suggests that these claims have a tendency to range from overly optimistic to downright erroneous. In the next section, we’ll take a close look at this evidence while answering some of the most frequently asked questions about reverse dieting.

Frequently Asked Questions

We’ve covered the theoretical rationale for reverse dieting and the common claims that arise from this conceptual framework. Unfortunately, there are many gaps in the theory, which starts to unravel when you dig into the most relevant scientific evidence. The most systematic and organized way to present this information is to provide evidence-based answers to some of the most frequently asked questions about reverse dieting. But before I dig into this literature, I want to acknowledge a major limitation related to how most studies in this area measure and report energy expenditure. 

Total daily energy expenditure (TDEE) describes the total number of kilocalories we burn in a given day, and it is made up of four components, which are presented in Figure 2:

• Basal Metabolic Rate (~70% of TDEE in general population)
  • Also known as “resting metabolic rate.” The modest distinction between these terms is irrelevant for the present article, so they’ll be used interchangeably
  • This describes the energy required to simply keep our body “on,” at rest, assuming we lay in bed all day without moving or eating
• Thermic effect of feeding (~10% of TDEE in general population)
  • This describes the energy used in the process of eating, digesting, metabolizing, and storing food
• Exercise Activity Thermogenesis (~5% of TDEE, depending on how much you exercise)
  • This describes the energy used during structured, intentional exercise
• Non-Exercise Activity Thermogenesis (~15% of TDEE, depending on your activity level)
  • This describes the energy used for any movement that isn’t purposeful exercise. This would include walking around your school or office, doing yard work, taking out the trash, and even fidgeting in your chair

Of the four main components of TDEE, NEAT is the one that is most dramatically impacted by metabolic adaptation. However, most of the research related to metabolic adaptation focuses on resting metabolic rate (RMR) rather than TDEE or NEAT. This is unfortunate but understandable, given that it’s far easier to measure RMR than NEAT or TDEE. So, we basically have two options: 1) we can assume that RMR reduction can be used as a decent proxy that roughly correlates with overall metabolic adaptation, such that folks experiencing larger drops in RMR are the same folks experiencing large drops in NEAT and, by extension, TDEE; or 2) we can reject this assumption, which means we know virtually nothing about reverse dieting, such that an evidence-based justification becomes nearly impossible. The point of this article is to highlight the lack of evidence for reverse dieting, so option #2 would make my job very easy. However, let’s be charitable, embrace option #1, and dig into the research.

Do metabolic rates get “damaged”?

No. 

As described by Dulloo (Figure 3), adaptive reductions in energy expenditure are driven by a combination of two related (but distinct) factors: the presence of an energy deficit, and the loss of fat tissue. In this context, metabolic adaptation has two separate components: the adipose-specific component, driven by reductions in fat mass, and the non-specific component, driven by the presence of an energy deficit. When a person transitions from an energy deficit (negative energy balance) to a calorie intake that supports weight maintenance (neutral energy balance), the non-specific portion of metabolic adaptation is reversed. When they regain the fat they had originally lost, the remainder of metabolic adaptation is reversed. 

Some of the earliest metabolic adaptation research comes from the Minnesota Starvation Experiment, which was carried out in the 1940s. In this groundbreaking study, the authors clarify what they mean as they discuss “adaptations” in metabolic rate: “By adaptation we generally mean simply a useful adjustment to altered circumstances.” When we spend a lot of time in the heat, our bodies adapt; for example, we sweat more, and our sweat becomes more dilute. When we stop spending so much time in the heat, the adaptations are reversed. Metabolic adaptation is similar in nature; it is an adaptive adjustment to insufficient energy availability, both in the short term (a current energy deficit) and the long term (a loss of fat mass). As these stimuli are removed, the adaptations are reversed. So, there’s no permanent or persistent damage going on here; metabolic adaptation is merely an adjustment that occurs in response to changing circumstances. 

Do low metabolic rates play a major role in preventing weight loss or promoting weight regain?

It doesn’t appear so. 

Reverse dieting advocates love to sell you a concise story about how your damaged metabolism is the root of your weight loss problems, and a reverse diet is the clear solution. They argue that your metabolic rate has grinded to a halt, which makes further weight loss attempts futile, and all but ensures rapid weight regain once your current diet ends. That sounds intuitive (and lends itself to some exciting marketing), but it’s incompatible with the latest research. 

In a 2021 study, Martins et al found that metabolic adaptation was associated with less fat loss over the course of a diet intervention. However, participants lost an average of 14kg in the study, and the average magnitude of metabolic adaptation (adaptive reduction in resting metabolic rate) was only 92kcal/day. The results indicated that each 50-kcal increase in metabolic adaptation was associated with a 0.5kg reduction in weight loss. So, the folks with greater-than-average metabolic adaptation were generally losing 12 or 13kg instead of 14kg – not exactly an insurmountable roadblock.

In a 2022 study, the same researchers reported that metabolic adaptation delayed weight loss, such that more time was needed to reach a given weight loss goal. In this study, participants lost an average of 12.5kg over about 155 days. The average magnitude of metabolic adaptation was only 46kcal/day. The results indicated that each 10-kcal increase in metabolic adaptation delayed weight loss by one day. So, the folks with greater-than-average metabolic adaptation generally had to prolong their diet by an extra week or two. Again, not a particularly big deal.

This same group published another paper back in 2020, which indicated that metabolic adaptation is not a major barrier to successfully maintaining weight loss. In the study, participants lost an average of 12kg; they regained about 52% of it within one year, and regained about 89% within two years. Immediately after the weight loss intervention, the average magnitude of metabolic adaptation was 54kcal/day. This magnitude of metabolic adaptation was not predictive of how much weight these individuals would gain over the following 1-2 years. These findings are very compatible with another study featuring an even longer follow-up period. Fothergill et al measured changes in metabolic rate and body composition before, immediately after, and six years after “The Biggest Loser” competition. Given the extreme nature of this competition, substantial drops in resting metabolic rate were observed. However, metabolic adaptation measured directly after weight loss was not predictive of weight regain over the six-year follow-up period. 

In fact, the magnitude of metabolic adaptation at the six-year mark was positively correlated with successful maintenance of weight loss. Having said that, I’m certainly not suggesting that metabolic adaptation makes weight maintenance easier. There’s a much more straightforward explanation: metabolic adaptation at the six-year mark was correlated with successful weight maintenance because metabolic adaptation should only persist in the people who are successfully keeping the weight off. This highlights an important observation that helps us reframe metabolic adaptation in a more helpful way. Metabolic adaptation might help us understand why one person loses a little more fat than another person during a weight loss intervention, or why one person needs a few extra weeks of dieting compared to someone else. However, metabolic adaptation does not stop weight loss in its tracks. Furthermore, when it comes to maintaining weight loss over time, metabolic adaptation is not a precursor to automatic weight regain; if anything, its persistence is a lingering marker of successful maintenance. With this in mind, the common perspective that people need reverse dieting to enable continued weight loss or to prevent weight regain doesn’t hold water.

When you look at studies identifying predictors of weight loss success or long-term weight maintenance, you see that important factors include adherence to lifestyle modifications, eating behavior characteristics, satiety-promoting strategies, lean mass retention, regular self-monitoring, and plenty of physical activity. Metabolic rate has very little to do with it. 

In fact, a large, recent study using gold standard measurement techniques found that TDEE at baseline was not associated with body-fat percentage, and that longitudinal increases in adjusted TDEE (accounting for fat mass, fat-free mass, age, and sex) were positively correlated with weight change (that is, increases in adjusted TDEE were predictive of weight gain, not weight loss or resistance to weight gain). These authors concluded: “This suggests low [TDEE] is not a risk factor for, and high [TDEE] is not protective against, weight or body fat gain over the time intervals tested.” Recent studies also indicate that people who experience larger drops in energy expenditure during negative energy balance and more resistance to weight loss over time actually have higher energy expenditure at baseline than people who experience smaller drops and less resistance. Based on the totality of the available evidence, there is little to gain by attempting to induce small increases in energy expenditure through reverse dieting, whether or not those attempts are successful. If you had to make an evidence-based prediction, you’d actually expect lower energy expenditure at baseline to predict similar (or even better) outcomes related to metabolic adaptation and weight loss success.

In summary, the available research indicates that your baseline metabolic rate tells us very little about your ability to lose weight, and your metabolic rate at the end of a diet tells us very little about how likely you are to regain weight. Furthermore, there’s no evidence indicating that “building up” your metabolic rate (assuming you’re able to) would make future weight loss meaningfully easier, or would meaningfully reduce the likelihood of weight regain. 

Does reverse dieting resolve the effects of metabolic adaptation?

It doesn’t appear so.

When we created the MacroFactor diet app, we created three potential goals: gain weight, lose weight, or maintain weight. Several users asked why there was no option to select “reverse dieting” as a goal or mode of operation. I understand why some users might have assumed that it was an oversight, or that we were simply unaware of the magic surrounding this popular dietary strategy. In reality, this perspective couldn’t be farther from the truth. 

I didn’t come up with the concept of reverse dieting, but to the best of my knowledge, I was the first person to introduce this term into the peer-reviewed scientific literature. I first mentioned it in a review paper in 2014, which was the first paper I wrote as a graduate student. I described that reverse dieting had become popular among physique athletes, primarily as a strategy to navigate the turbulent period of time immediately following competition. It’s not unusual for physique athletes to regain 20-30 pounds after competitions, and you’d be amazed by how quickly this occurs when athletes decline to strategically plan their post-competition weight regain process. In other words, reverse dieting was (from my perspective) a method of guiding a structured period of controlled weight regain, rather than a strategic attempt to alter one’s metabolic rate. Nonetheless, reverse dieting was only discussed in a single, short paragraph, which ended by acknowledging: “While anecdotal reports of successful reverse dieting have led to an increase in its popularity, research is needed to evaluate its efficacy.”

I revisited the topic of reverse dieting in a case report that my team of collaborators published in 2017. I could be wrong, but to my knowledge, this was the second time reverse dieting was mentioned in the peer reviewed literature. The purpose of the paper was to document observations during (and after) the contest preparation of a single physique athlete. Since a case report merely describes the changes observed in a single individual, this paper couldn’t be used to determine if reverse dieting was better or worse than potential alternatives. Rather, it simply acknowledged that the study participant opted to implement a reverse dieting strategy after their competition. 

That same year, we published a separate study exploring physiological changes after competition in a small cohort of physique athletes. We didn’t manipulate how the physique athletes approached their post-competition recovery, but some competitors opted for more aggressive calorie increases and more rapid weight regain than others. As we’d expect based on previous studies, simply transitioning out of an energy deficit was associated with an acute increase in energy expenditure. This was a rapid change, happening in only a matter of days. However, over the next 4-6 weeks, we found that increases in metabolic rate were directly correlated to weight regain. Our findings supported previous research reporting three important observations about weight-reduced individuals: 1) metabolic rate is partially restored by eliminating the energy deficit (which doesn’t require reverse dieting); 2) the remainder of metabolic rate restoration is associated with fat regain (which is directly opposed by most reverse dieting strategies); and 3) fat is very efficiently regained when weight-reduced individuals establish positive energy balance, which directly questions the effectiveness of most reverse dieting approaches that aim to minimize fat regain. Nonetheless, this was only an observational study, and it did not directly compare reverse dieting to alternative strategies.

Three years later (in 2020), I collaborated with some researchers on a paper that compared and contrasted post-competition changes in a small group of physique athletes. This was a “case series,” which means we were simply observing changes in a small group of participants who were independently determining how to adjust their diet and training in the post-competition period. We didn’t have the ability to randomly assign groups or manipulate the participants’ diet or exercise habits, so we have to take these observations with a grain of salt. Nonetheless, the results were pretty unfavorable for reverse dieting.

After a competition, physique athletes generally have low body-fat levels, low leptin levels, and low resting metabolic rates. These are all pretty intuitive, and totally compatible with our understanding of metabolic adaptation. Some reverse dieting proponents suggest that reverse dieting will restore resting metabolic rate and hormone levels to pre-diet levels, without the need to regain fat in the process. In this case series, three of the participants appeared to implement dietary strategies that would fall under the “reverse dieting” umbrella (aiming to increase calorie intake without substantial weight gain), while the other four did not. As shown in Figure 4, fat regain was associated with changes in leptin; this is important, because drops in leptin drive metabolic adaptation, and metabolic adaptation is promptly reversed when subjects with metabolic adaptation are given injectable leptin. As shown in Figure 5, fat regain was also associated with restoration of metabolic rate. 

The statistical analyses of the study showed very straightforward patterns in which allowing oneself to regain weight and fat mass facilitated diet recovery and reversal of metabolic adaptation, while attempts to restrict weight regain appeared to interfere with recovery of metabolic rate. As we concluded in the paper: “Minor increases in body weight (< 5%) were inadequate to elicit improvements in physiological outcomes. Competitors could potentially expedite recovery by increasing caloric intake and reducing aerobic exercise to facilitate a more substantial rate of weight gain in the weeks following competition.” In other words, reverse dieting didn’t appear to work. Weight gain was attenuated, but recovery was delayed and suppression of metabolic rate persisted. This was admittedly not a tightly controlled study with rigorous control over exactly how and when calorie intake was manipulated, but it’s another piece of evidence that fails to support the most noteworthy claims associated with reverse dieting.

There are many gaps in the explanation of how reverse dieting should work, but one particularly large oversight of most reverse dieting narratives is that they completely ignore the impact of body fat. As noted previously, metabolic adaptation is primarily driven by drops in leptin, and leptin is responsive to both short-term and long-term energy status. Many reverse dieting proponents make it seem like an extra 50-100 Calories is going to radically change the physiological state of your body and send leptin through the roof, thereby reversing a wide range of adaptations orchestrated by the hypothalamus without any need to regain the fat mass that was lost. 

A major problem with that concept is that body fat is a highly influential regulator of leptin levels. The vast majority of our leptin is actually produced by fat cells, and they downregulate production when they start to shrink and lose energy content as fat loss progresses. This is one mechanism by which the human body defends body weight within a particular range, as described by the dual-intervention point model of weight regulation (Figure 6). This model posits that we have an “upper intervention point” and a “lower intervention point” for body-fat levels. While environmental and behavioral factors allow our body-fat level to freely fluctuate between these two thresholds, we start to run into friction as we approach either of them. 

For example, if you intentionally try to gain more weight after reaching your upper intervention point, you’ll almost certainly run into some difficulty. You might experience increases in energy expenditure, appetite reductions, and a number of other physiological adaptations that make it more challenging to gain additional weight. Similarly, when we try to go below our lower intervention point, we run into all of the aspects of metabolic adaptation that make the process a little bit more challenging (but certainly not impossible). This model is compatible with the fact that many people are able to successfully lose or gain weight (and maintain it) within certain boundaries, but also compatible with the fact that some people run into challenges earlier in the process than others, while virtually everyone experiences significant friction when they get down to extremely low body-fat levels. It’s also very compatible with the weight regain literature, which consistently indicates that the loss of fat mass is an independent driver of metabolic adaptation. 

If someone is well below their lower intervention point, their hypothalamus is going to try every trick in the book to conserve energy, and there’s no evidence to suggest that reverse dieting can overcome the powerful biological response to diminishing fat stores. It’s almost a certainty that different people have very different upper and lower intervention points, but there’s no getting around the fact that current body-fat level is an important regulator of the physiological changes we associate with metabolic adaptation. As reviewed by Dulloo, a considerable amount of research demonstrates that the loss of fat mass is an independent and persistent driver of metabolic adaptation, and there’s no evidence to believe that this particular component of metabolic adaptation is resolved by anything other than fat regain (or injectable leptin, which generally isn’t a feasible or accessible option). There’s no reason to suggest that increasing calorie intake can offset this particular component of metabolic adaptation, and plenty of evidence to suggest that it doesn’t.

In summary, our omission of an explicit reverse dieting feature in MacroFactor is not driven by lack of familiarity with reverse dieting, but rather by a very deep level of familiarity. It was a topic that I originally embraced with cautious optimism back in 2014, and spent several years exploring thereafter. However, as more evidence became available, including multiple studies that I personally assisted with, the theory became less and less tenable over time. In 2014, there wasn’t much evidence related to reverse dieting, so conclusions were extremely hard to draw. In 2022, we still don’t have extremely direct research, but the available evidence casts doubt on most of the exciting claims about reverse dieting.

Does reverse dieting increase or “supercharge” the metabolic rate of weight-reduced individuals?

No.

This type of claim probably comes from overfeeding studies in which participants are fed way more than they’re used to eating, and the researchers observe how their bodies respond to the extra energy intake. Notably, these studies have questionable relevance to reverse dieting – they involve increasing calorie intake for participants who are at their typical, stable body weight at baseline, not participants who recently completed a weight loss phase or are trying to maintain a substantial degree of prior weight loss. In most cases, group-level averages for energy expenditure tend to increase during overfeeding. However, there are two important issues with leaning on this evidence to support reverse dieting for individuals who recently finished a diet, or identify as “chronic dieters.” We can collectively refer to these two populations as “weight-reduced individuals,” or people who are currently below their “natural” weight due to weight loss.

The first issue is that inter-individual responses matter. In overfeeding studies, heterogeneous increases in TDEE are often observed; these increases are primarily driven by increases in NEAT, which are most pronounced in the individuals who gain the least amount of fat during the overfeeding period. In other words, researchers generally find that there are weight gain-resistant individuals who experience robust and pronounced increases in TDEE when they’re overfed, whereas other individuals readily gain fat in a caloric surplus. As shown in Figure 7, people who are innately resistant to fat gain experience large increases in energy expenditure, while people who are innately prone to fat gain experience minimal changes in energy expenditure. 

This heterogeneity from person to person is hugely important, and brings us to a critically important concept: metabolic phenotypes. A phenotype refers to some set of observable traits or characteristics; when discussed in the context of metabolism, we often distinguish between thrifty and spendthrift phenotypes. Someone with a thrifty phenotype is very good at conserving energy; they gain fat very efficiently and experience minimal changes in TDEE during overfeeding, but they resist weight loss and experience larger reductions in energy expenditure during weight loss diets. On the other hand, someone with a spendthrift phenotype is very wasteful of energy; they resist fat gain and experience large increases in TDEE during overfeeding, but they lose weight readily and experience minimal reductions in energy expenditure during weight loss diets. 

A recent study by Hollstein et al explored these divergent phenotypes in greater detail. This might sound a bit surprising, but people with thrifty phenotypes actually had greater TDEE than spendthrift individuals in neutral energy balance at baseline (Figure 8). The characteristic that makes them “thrifty” is not that their TDEE is always low (it isn’t), but rather that their TDEE drops precipitously when they initiate an energy deficit. This explains why other studies have shown that thrifty individuals tend to experience more friction during longitudinal weight loss interventions; they more readily experience metabolic adaptation, and therefore need to push a little harder (i.e., drop calories a little further or diet a little longer) to achieve the same weight loss results. Having said that, phenotypes aren’t exclusively impactful during negative energy balance – they impact responses to overfeeding as well. As shown in Figure 8, thrifty individuals don’t only experience larger drops in TDEE during underfeeding, but also experience smaller increases in TDEE during overfeeding. In other words, even if very gradual calorie increases (i.e., reverse dieting) were to successfully promote increases in TDEE, it would be least likely to help the people who want it the most: individuals who readily gain fat and experience more pronounced metabolic adaptation during weight loss.

The spendthrift group experienced significantly larger increases in total (24-hour) energy expenditure in response to both low-protein (p = 0.002) and high-protein (p = 0.03) overfeeding. 

I have fielded many questions about reverse dieting over the years, and I can’t recall a single one coming from someone who reported a history of struggling to gain weight. In almost all cases, reverse dieting is embraced by folks who have a history (either acute or chronic) of weight loss dieting, which is directly correlated to having some propensity for fat gain. People are typically pursuing weight loss diets because they have previously gained weight unintentionally, or because their goal physique involves maintaining a lower amount of fat mass than they’ve accrued over time. From this perspective, TDEE increases in response to overfeeding are an obstacle for people struggling to gain weight, not a solution for people who struggle to lose weight or maintain prior weight loss. The purported benefit of overfeeding (increased TDEE) is least accessible for the folks with the greatest interest in reverse dieting (those who have pursued weight loss [and struggled] in response to unintentional weight gain). It appears that large increases in energy expenditure during overfeeding reflect an innate characteristic of people who are resistant to fat gain, not a physiological “mode” you can unlock through reverse dieting. 

Another very important issue with using overfeeding studies to promote reverse dieting is that weight gain and weight regain are two very different things. Conceptually, reverse dieting exists as a remedy for metabolic adaptation, which is exclusively relevant to people who just finished a diet, or suspect they’re experiencing some type of long-term downregulation of metabolic rate due to past dieting. Unless an individual is innately resistant to fat gain or they’re currently experiencing substantial metabolic adaptation, there’s absolutely no reason to believe reverse dieting will do anything at all, from a physiological perspective. We know what small, gradual, long-term energy increases in energy intake do for weight-stable people at their natural body weights in the general population: they fuel an average weight gain of around 0.5-1 kg/year, and population-level BMI values trend upward over time. That’s not a solution to metabolic adaptation, it’s the precursor to why many people start dieting in the first place. Reverse dieting can’t “supercharge” anything; at best, it may aim to reverse the effects of metabolic adaptation and return one’s metabolic rate closer to their baseline. 

Unfortunately, as reviewed by McLean et al, there are widespread and multifaceted physiological adaptations that make people particularly susceptible to weight gain after a successful weight loss diet. In fact, as reviewed by Dulloo et al, these adaptations are so pronounced that many people end up regaining more weight than they lost in the first place. These observations help explain why weight regain is so common after successful weight loss interventions. All of that is to say, we shouldn’t assume that physiological responses to extreme overfeeding protocols in people at their natural body weight are reflective of how reduced-weight individuals will respond to tiny calorie increases after dieting. In fact, the research strongly suggests that these are very different physiological states, and that individuals are more likely to store extra calories as fat mass (rather than burn them off) when they’re in a weight-reduced state (i.e., just about everyone who would be interested in reverse dieting). When we overfeed people at their natural weight, the weight-resistance folks ramp up energy expenditure, and everyone else just stores a bunch of fat. When we overfeed people at the end of a weight loss diet, just about everyone stores a bunch of fat (although the rate and magnitude of fat storage still varies from person to person). It’s extremely difficult to imagine a world in which small, gradual increases in calorie intake are reliably met with robust adaptations to prevent weight gain, while we see widespread, gradual weight gain at the population level and extremely high rates of weight regain in published weight loss interventions. 

So, we’ve established that overfeeding studies do not provide evidence supporting reverse dieting, people at reduced body weights are uniquely predisposed to weight regain when calorie intake is increased, there are substantial individual differences with regards to the propensity for (or resistance to) weight gain during overfeeding, and the individuals most likely to experience metabolic adaptation during weight loss are least likely to experience increases in energy expenditure during overfeeding. In other words, even if reverse dieting actually delivered on its promises and did what it’s claimed to do, it is least likely to help the people who need it the most. People who experience the largest amount of metabolic adaptation experience the smallest increases in energy expenditure when calorie intake is increased, and are more likely to regain fat in the process rather than ramping up their energy expenditure.

Does reverse dieting immediately after a weight loss phase prevent future weight regain or facilitate a smoother transition to a maintenance phase?

It doesn’t appear so. 

People often focus on the semi-starvation part of the Minnesota Starvation Experiment, but there was also a controlled, 12-week refeeding phase after the semi-starvation period, which was then followed by an uncontrolled refeeding phase. Notably, the researchers split participants into four different groups (Z, L, G, and T), with each group reintroducing calories at different rates. For example, the slowest weight regain group started with an average energy intake of only 1930 kcal/day (working up to 2999 kcal/day over 12 weeks), while the fasted weight regain group started at 2944 kcal/day (working up to 4014 kcal/day). The slow group was essentially reverse dieting; they stayed approximately weight stable for the first six weeks with just slightly positive energy balance (gaining only 1.2 grams per day), and didn’t start regaining much weight until around the two-month mark (Figure 9).

As seen in Figure 9, smaller caloric surpluses definitely led to more gradual increases in body weight during this controlled refeeding period. But what happens after week 12, when participants are no longer on super tightly controlled diets? The participants in the slower weight regain groups (Z and L) promptly rebounded, fully catching up with the participants in the faster weight regain groups (G and T). At the start of the 8-week uncontrolled refeeding phase, the slower weight regains weighed (on average) about 5kg less than the faster weight regainers. After 8 weeks, this gap shrunk to a negligible difference of 0.4kg. If there was ever any meaningful metabolic advantage (and there’s no evidence of that, to be clear), it vanished rapidly, and the extra restraint and sacrifice during early refeeding conferred no enduring benefit pertaining to weight regain.  

You might be wondering why this is even relevant. Why should we be looking to extreme semi-starvation experiments for insights related to more typical, “real-world” dieting strategies? I understand reservations about drawing practical conclusions about dieting from such an extreme type of experiment, and about the fact that this wasn’t explicitly designed to be a reverse dieting intervention. The problem is, I can’t think of a population where reverse dieting has been shown to live up to the popular claims about it. For example, physique athletes who appeared to adopt a reverse dieting approach seemed to simply delay their post-competition recovery, with hormone levels and resting metabolic rate failing to budge. Further, it’s difficult to suggest that better outcomes are likely in populations with higher body-fat levels or less aggressive diet interventions. Theoretically, reverse dieting should be most effective in scenarios where metabolic adaptation is most extreme, and to my knowledge, the Minnesota Starvation Experiment reports some of the most dramatic metabolic adaptation ever observed in the scientific literature. Anything that’s supposed to attenuate or reverse metabolic adaptation should have its largest and most obvious effect in this type of scenario; such dramatic metabolic adaptation should basically stack the deck in a manner that exaggerates the effectiveness of the strategy. In other words, if it didn’t work in this study, it probably doesn’t work. 

Does reverse dieting make your next weight loss phase easier?

Probably not. 

For this to be the case, we’d need two things to be true: 1) having a high metabolic rate at the beginning of a diet should be predictive of weight loss success, and 2) any increase in metabolic rate caused by reverse dieting would need to persist throughout the next weight loss phase. 

As previously discussed, high metabolic rates are not reliably predictive of resistance to future weight gain or more successful weight loss attempts. In fact, Nunes et al found that individuals with the thrifty metabolic phenotype have higher energy expenditure at baseline, but still face greater resistance to weight loss than individuals with the spendthrift phenotype. (As a quick note – readers may notice that the abstract of Nunes et al reports higher baseline energy intake rather than expenditure in the thrifty group, but in this particular instance, the two values are equivalent. Further, the results section of the full paper contradicts this finding reported in the abstract; I have confirmed with the lead author that the abstract is indeed correct, and the results section will be updated to reflect this). The challenge with a thrifty metabolic phenotype is not starting the diet with low TDEE; the challenge is that TDEE drops during the weight loss phase. There is absolutely no evidence to suggest that building up to a higher metabolic rate or TDEE before a diet alleviates or circumvents this challenge.

Furthermore, it’s exceedingly difficult to suggest that any pre-diet increases in metabolic rate would persist into the next weight loss phase. In the Hollstein study on metabolic phenotypes, they categorized participants based on their metabolic response to a single day of fasting. Thrifty individuals had higher TDEE at baseline (in neutral energy balance), but rapidly experienced larger drops in TDEE when negative energy balance was achieved. As previously discussed, this study also found that thrifty individuals experienced smaller increases in TDEE during overfeeding. So, people who are most susceptible to metabolic adaptation seem to have higher, not lower, TDEE at baseline, which contradicts the concept that they need to build up their metabolic rate before dieting. Furthermore, they have the lowest likelihood of actually increasing their TDEE through reverse dieting, and the available evidence suggests that any such benefit would be completely wiped out almost immediately when they begin their next weight loss diet. Transient gains in energy expenditure are unlikely for people with the thrifty metabolic phenotype, but even if such gains were achieved, transient gains should be transiently lost and confer no persisting benefit. 

If reverse dieting doesn’t fix metabolic adaptation, what should we do about it?

The bad news is that we can’t do much about metabolic adaptation, as far as we currently know. I used to have cautious optimism about reverse dieting, but research over the last few years has obviously stifled my optimism considerably. Similarly, I used to have cautious optimism about refeeds and diet breaks, but recent research suggests that refeeds have minimal impact for the typical dieter. Diet breaks (short, recurring, 1-2 week maintenance phases) do have some promising evidence, but there are plenty of studies that also report underwhelming results, including research that I’ve personally collaborated on. As previously discussed, the available research hints at a number of subjective and behavioral improvements related to hunger, satiety, diet adherence, mood, and perceived energy level, in addition to improved performance. Notably, these effects are most pronounced during the diet break itself, when calories are still up around maintenance level. However, there’s insufficient evidence to suggest that diet breaks meaningfully attenuate reductions in energy expenditure in a manner that persists throughout the entire weight loss period. 

Now, for the good news. As discussed previously, the available research suggests that metabolic adaptation can add some friction to the weight loss process, but it’s absolutely not an insurmountable roadblock. People who experience larger magnitudes of metabolic adaptation during well-controlled diet interventions still achieve great results, they just need to reduce their calories a little more or diet a little longer than their less adapted counterparts. With this in mind, I will offer three suggestions about what we ought to do about metabolic adaptation.

First, it’s important to recognize that metabolic adaptation provides some extra friction, but it is not mysterious, unquantifiable, or insurmountable. There is ample evidence of people achieving tremendous weight loss results in the face of directly quantifiable metabolic adaptation.

Second, it’s advisable to avoid exacerbating metabolic adaptation (and other associated effects related to relative energy deficiency) by following some basic “best practices” for weight loss. By avoiding excessively large caloric deficits (i.e., very rapid rates of weight loss), eating plenty of protein, keeping physical activity levels high, incorporating some resistance training, avoiding body composition goals that keep us way below our “lower intervention point” for extended periods of time, and implementing diet breaks as needed (as long as we need, and as frequently as we need), we’ve done just about all we can to set ourselves up for a successful weight loss phase. Just to reiterate, the diet breaks are mostly for psychological and subjective benefits that come with a brief reprieve from the rigors of dieting, not to directly circumvent or reverse metabolic adaptation to a meaningful degree.

Third, we should be aiming to quantify and account for metabolic adaptation, not aiming to totally prevent or counter it. This is one of the main reasons that MacroFactor places so much emphasis on the running energy expenditure estimate, and makes the expenditure curve so visible within the app. Even if we can’t stop metabolic adaptation in its tracks or reverse its effects on command, it’s surprisingly reassuring to watch the expenditure curve react as we progress throughout a weight loss phase. This gives us actionable data so we can make appropriate calorie adjustments (and, if necessary, adjust our weight loss timeline) to ensure a smooth and successful weight loss phase. It takes the mystery and guesswork out of metabolic adaptation, and makes it a tangible and quantifiable effect that we can accommodate and account for along the way. While making this adjustment process easy and effective was a high priority when designing MacroFactor, it’s also very possible to quantify and accommodate metabolic adaptation without MacroFactor. So, whether you use MacroFactor or not, the evidence-based strategies and perspectives in this section should be quite helpful if you pursue a weight loss goal in the future.

Why Are There So Many Positive “Reverse Dieting” Anecdotes?

If we focus exclusively on the scientific literature, the case for reverse dieting isn’t very strong (at all). However, it’s not uncommon to hear enthusiastically positive anecdotes about reverse dieting helping people eat more calories while staying lean or avoiding precipitous fat gain. I suspect that four separate illusions may make reverse dieting seem more effective than a boring old maintenance phase, and that these illusions give rise to the anecdotes that fuel the hype surrounding reverse dieting. 

Illusion #1: Improved consistency and dietary adherence

People have a tendency to underestimate their habitual energy intake (I’m not judging, by the way – this applies to me as much as anybody). Even registered dietitians, with extensive training and expertise in nutrition, routinely underestimate their energy intake by over 20% on average. For people without such relevant training and expertise, it’s not uncommon to see calorie intake underreported by an average of 47%, while physical activity is overreported by an average of 51%. To be clear, misreporting is not necessarily indicative of dishonesty – tracking this stuff can be very hard to do if you aren’t equipped with sufficient guidance and tools to facilitate the process. 

Even if we are very skilled and precise with diet tracking when adherence is high and our diet is a top priority, extra calories tend to fly under the radar and sneak into our weekly diet when adherence is spotty or nutrition goals are on the backburner. For example, we might have a typical “base” diet (the meals we routinely lean on day-to-day) consisting of 2300 kcal/day. So, we view our body composition and weight changes through an intuitive lens: this is what happens when I eat 2300 kcal/day. However, what if you’ve got a picky child and you routinely eat their leftovers, or you have a tendency to engage in untracked snacking from time to time, or you forgot to account for Thursday night being pizza night, or you tend to let loose a bit on the weekends? A casually tracked “base diet” of 2300 kcal/day might end up averaging 2800 kcal/day if you were to meticulously track your intakes for an entire week.

Reverse dieting necessarily insists on shockingly consistent and detailed tracking. I can’t fathom how one could aim to accomplish reverse dieting without such a rigid approach to tracking. If the “big change” this week is adding 10g of carbs to your diet, anything short of unsustainably meticulous and precise tracking habits would lead to your entire reverse dieting experiment getting wiped out by rounding error or tiny, inconsequential tracking oversights. If you believe that accidentally consuming 2160 kcal instead of 2200 kcal (i.e., failing to add your extra 10g of carbs) is going to drop you from a reverse diet to a boring old maintenance phase and stop your metabolic-boosting progress in its tracks, you’ve set absolute perfection as the goal for your dietary tracking. 

As a result, I suspect that some people who have great experiences with reverse dieting (and subsequently rave about it) are probably tracking more accurately than they ever have in their entire life, and their perception of a “boosted” metabolic rate is a consequence of removing the tracking error that has previously caused them to underestimate their calorie intake. For example, someone might be shocked to find that they’re now (after reverse dieting) able to maintain a body weight of 160lbs while eating 2700 kcal/day, while they used to weigh 160lbs back when they were eating only 2300 kcal/day. If that memory of maintaining 2300 kcal/day was based on loose, inconsistent tracking, it’s quite possible that they were eating around 2700 kcal/day back then, but simply underestimating their intake. With this in mind, one potential illusion fueling the reverse dieting hype is that people are comparing current, meticulously tracked intakes with memories of less precisely (or erroneously) tracked intakes in the past, which means they are no longer underestimating their dietary intake to the same degree as they once did. 

Illusion #2: Practically speaking, a person’s “maintenance calorie target” is more like a range of targets

Imagine your “true” maintenance calorie level is 2200 kcal/day. In this hypothetical scenario, your TDEE is consistently 2200 kcal/day, and if you eat 2200 kcal/day, your body weight is maintained perfectly. Would you experience precipitous weight loss if you started eating 2100 kcal/day? Would you rapidly gain a substantial amount of fat if you started eating 2300 kcal/day? The answer to both is no.

Let’s oversimplify things a bit and pretend that TDEE is perfectly stable, and that a surplus of 9,441 kcal is required to gain a kilogram of fat (as is predicted by calculations). By dropping from 2200 kcal/day to 2100 kcal/day, it would take over 3 months to lose a kilogram of fat. By increasing from 2200 kcal/day to 2300 kcal/day, it would take over 3 months to gain a kilogram of fat. However, since body weight tends to fluctuate pretty substantially from day-to-day, it might take considerably longer to actually recognize that weight change is occurring. In other words, without extremely diligent weight tracking and relatively sophisticated functions to smooth out your weight trend and minimize the impact of day-to-day fluctuations, you would almost certainly perceive yourself as being “approximately at maintenance” with all three caloric intakes (2100, 2200, and 2300 kcal/day). If you’re in a small deficit or a small surplus and you’re monitoring weight trends with the naked eye, it will take a long time to actually detect the weight change with any degree of confidence.

So, without extremely diligent tracking and the use of effective weight trending software, it’s not unusual for someone to perceive themselves as being “at maintenance” within a fairly broad range of calorie intakes – this “maintenance range” can sometimes be as wide as 400 kcal. As a result, it’s quite plausible that someone with a history of concerns about weight gain might be erring on the low side of this range (to prevent the risk of unintended weight gain), and might actually be in a 200 kcal/day deficit despite what appears to be a fairly stable body weight. As far as they’re concerned, they’re at their “maintenance” calorie level of 2000 kcal/day, despite a TDEE of 2200 kcal/day. Body weight is technically decreasing, but at such a slow rate that it’s hard to see amid the comparatively larger day-to-day fluctuations. That individual might hear about reverse dieting, decide to get proactive about increasing their caloric intake, and slowly work up to a 200 kcal/day surplus. At this intake, their body weight is slowly increasing, but at such a slow rate that it’s difficult to identify over short time scales. In this hypothetical scenario, someone could easily reverse diet from 2000 to 2400 kcal/day and genuinely perceive themself as being “at maintenance” at the beginning and end of that process, without actually changing their energy expenditure at all. 

Illusion #3: Calorie intake is instantaneous, but weight change is cumulative

Some of the most common anecdotes pertaining to reverse dieting are shared by people who are stunned about their current leanness relative to their current energy intake. For example: “I can’t believe I’m eating 3300 kcal/day at this weight; I used to maintain this weight when I was only eating 2800 kcal/day!” However, there’s often an important detail that goes unstated: they haven’t been eating 3300 kcal/day for very long. And that matters.

To make this mathematical concept a bit more tangible, let’s walk through a couple of very oversimplified examples that assume TDEE is constant, just for demonstrative purposes. 

First, consider someone who reaches their weight loss goal and decides they want to shift to a more sustainable calorie target. At the end of their diet, their TDEE is 2600 kcal/day. In scenario A, they switch to a maintenance phase with a calorie target of 2600 kcal/day. Their cumulative energy balance over the next 16 weeks is totally neutral (zero), because energy intake matches energy expenditure every single day. However, in scenario B, they decide to do a 16-week reverse diet, starting at a daily calorie target of 2225 kcal/day, and increasing their daily calorie target by 50 kcal/day every week. Over 16 weeks, they build up their energy intake from 2225 kcal/day to 2975 kcal/day. Since they approached calorie increases so slowly, they were actually still in a small calorie deficit until week 9, and then steadily ramped up their energy surplus for the remainder of the 16-week period. As a result, cumulative energy balance over the entire 16-week window is still perfectly neutral (zero). In scenario A, the person perceives a boring maintenance phase where nothing interesting happened, and they were stuck at their normal maintenance intake of 2600 kcal/day. In scenario B, the person perceives an exciting process by which they ramped up to nearly 3,000 kcal/day without gaining weight, which implies that they’ve supercharged their energy expenditure to a rate they never imagined possible. The only issue is they didn’t – they failed to gain weight because their long-term energy balance was neutral, with no magic or physiology required to explain the discrepancy. This person might very understandably perceive that reverse dieting allowed them to unlock an extra 375 kcal/day without any extra weight gain, but it didn’t. If they continue with the approach described in scenario B, they’ll eventually (over a long time scale) end up gaining more weight than in scenario A. Scenarios A and B are graphically represented in Figure 10.

Now, let’s consider another example. Once again, the person reaches their weight loss goal and decides they want to shift to a more sustainable calorie target, with a TDEE of 2600 kcal/day. In scenario C, the person jumps straight to a moderate surplus, because they’d prefer some more dietary flexibility and they’re totally fine with a little bit of weight regain. Each day, this person eats 2975 kcal/day, which yields a caloric surplus of 375 kcal/day. Over a 16-week period, this results in a cumulative energy surplus of 42,000 kcal, which results in some weight gain. In scenario D, the person decides to reverse diet very aggressively, starting at 2225 kcal/day and adding 100 kcal/week, ultimately building up to a daily calorie target of 3725 kcal/day. Since they increased calories incrementally over time, they were actually still in a calorie deficit until week 5. Over 16 weeks, the cumulative energy surplus still ended up being 42,000 kcal, just like it was in scenario C. As a result, both strategies result in identical weight gain. If this person compares their new reverse dieting strategy to their past experiences, they would certainly get the impression that they’ve supercharged their metabolic rate to a remarkable extent. In scenario D, it would absolutely seem as if they unlocked an extra 800 kcal/day without any additional weight gain when compared to scenario C, and it would seem like they’re now able to maintain the same physique they used to, but at a dramatically higher daily calorie target (Figure 11). But it’s an illusion, not an adaptation. If they continue with the approach described in scenario D, they’ll eventually (over a long time scale) end up gaining more weight than in scenario C.

Illusion #4: Mixing up “cause” and “effect”

To explain this particular illusion, I want to lean on a training-related analogy. In resistance training, “progressive overload” is a critically important principle, but one that is often misapplied. Many people suggest that progressive overload is driven by small, acute program manipulations (e.g., adding more weight to the bar this week will make me stronger next week, but failing to add weight will not fuel further progress). However, as argued by Minor et al, it’s more likely that the ability to add more weight to the bar is actually the result of implementing a sufficient training stimulus in previous weeks. 

The purpose of a training session isn’t to achieve the maximum possible training stimulus every single workout, but rather to consistently apply a training stimulus that is merely challenging enough to promote further adaptations. As we get stronger, the minimum threshold for an effective training stimulus increases, and we need to continuously make workouts more challenging to “keep up” with our gains (strength adaptations). In other words, adding weight to the bar is the consequence of progressive overload, which is induced by consistently applying an adequate training stimulus. So, you’re not stronger next week as a direct consequence of adding 5 pounds to the bar this week – you’re able to add 5 pounds this week because you’ve already gotten stronger. As you continue to get stronger, you’ll need to continue adding weight to the bar in order to keep up with your ever-increasing minimum threshold for an effective training stimulus.

So, what does this have to do with reverse dieting?

I suspect that there’s an analogous situation going on with dietary manipulations. Reverse dieters may believe that their TDEE is going up because they are actively driving it up by meticulously, methodically manipulating dietary variables while remaining at a constant body weight. But what if those dietary manipulations aren’t driving anything at all? What if they’re more of a consequence than a cause?

As discussed previously, evidence indicates that metabolic adaptation is driven by two separate (but related) causes: the loss of fat mass, and the presence of an energy deficit. Eliminating an energy deficit seems to alleviate or attenuate many of the issues associated with relative energy deficiency (except for the ones independently caused by low fat mass), while also increasing energy expenditure. Notably, the easiest and most straightforward path to “eliminating an energy deficit” is to simply jump to maintenance calories. If jumping to maintenance calories reverses some of the energy expenditure suppression caused by an energy deficit (it does), then it’s quite likely that energy expenditure will actually climb a bit when you make the first calorie increase. As a result, you might find that this “maintenance level” will, eventually, no longer be your maintenance level; energy expenditure may increase, such that you eventually find yourself in a very small deficit. At this point, you can increase calories again (by a very small amount) to reestablish maintenance. Once again, you might find that energy expenditure further increases after you eliminate the small energy deficit, and it may be time for another very small calorie increase.

Speaking purely in terms of implementation, the scenario described above looks exactly like reverse dieting (slowly increasing calorie intake over time while maintaining a fairly stable body weight). However, there’s one critical distinction: in this scenario, reverse dieting is the effect, not the cause. Tiny calorie increases aren’t driving energy expenditure upward; you’re able to make the tiny calorie increases because energy expenditure is climbing. The causative factor that drives energy expenditure upward is not an extra 5-10 grams of carbohydrate; it’s transitioning from negative energy balance to neutral energy balance. This concept is graphically depicted in Figure 12.

Flipping cause and effect might seem like a matter of semantics, but it’s actually important. Maintenance phases tend to be relatively flexible, low-stress diet phases. Rather than striving for perfection, you’re just trying to keep body weight relatively stable over time. If it starts drifting up or down, that’s totally fine – you simply adjust your calorie target and keep moving forward. In contrast, reverse dieting typically involves very small dietary adjustments and suggests that being weight stable at a daily intake of 2050 kcal/day is meaningfully different from being weight stable at a daily intake of 2010 kcal/day. This approach necessarily implies razor-thin allowances for going slightly over or under dietary targets. It introduces a stressful and tedious demand for precision, while reinforcing rigid cognitive restraint (which is detrimental, as I explain in this article). As a result, we should require very strong evidence that reverse dieting is more effective than a simple maintenance phase before opting in. If reverse dieting is actually the effect rather than the cause, the entire exercise becomes redundant, with high stress and effort but negligible reward. 

When reverse dieting is viewed as the “cause,” it’s completely speculative, unsupported by evidence, and (in my opinion) somewhat implausible. For example, it posits that tiny dietary adjustments represent physiologically meaningful “interventions,” despite the fact that we treat potentially larger variations in daily energy balance (such as food label inaccuracies, extra oil left on dishes or pans, and unnoticeable day-to-day variation in non-exercise activities) as totally ignorable (as we should). It also posits that small calorie increases beyond the current maintenance level serve as a “metabolic rate booster” in people who either just finished a diet or are chronic dieters. This perspective relies on ignoring virtually all evidence pertaining to weight gain dynamics and post-diet weight regain. Recent or chronic dieters in a weight-reduced state should be particularly susceptible to weight gain in the presence of small calorie increases beyond the maintenance level, and there’s no evidence to suggest that this somehow leads to increased TDEE in the absence of efficient weight regain. 

In contrast, when you view “reverse dieting” (in this case, the ability to nudge maintenance calories upward) as the effect rather than the cause, you immediately find much stronger evidence to support the idea. We know that the presence of an energy deficit suppresses metabolic rate, we know that this effect is transient in nature, and we know that this effect is reversed when approximately neutral energy balance (maintenance) is restored. 

Important Clarifications

I want to clarify two very important points here: I am not doubting the experiences reported by people with successful reverse dieting anecdotes, nor am I implying that such individuals are “foolish” for overestimating the impact of reverse dieting. Illusions aside, people probably experience some very nice things when they reverse diet. When someone transitions from an energy deficit to neutral energy balance, they are likely to experience a small increase in metabolic rate, reversal of some symptoms of relative energy deficiency, and a number of subjective improvements related to hunger, satiety, mood, and energy level that could positively impact their activity level and overall quality of life. If they’re an avid exerciser, they might also notice improved performance and reduced symptoms associated with overreaching or overtraining. It’s also possible that they’ll experience less compensation for calories burned during exercise and other physical activities. During an energy deficit, we tend to offset some of the calories burned during exercise by reducing other components of TDEE. However, this appears to be attenuated during neutral or positive energy balance.

So, there are definitely evidence-based explanations for why a person might experience a small increase in metabolic rate, feel better, move more, or perform better as their reverse diet progresses. In other words, the beneficial effects aren’t imaginary, and the anecdotes aren’t flukes or fabrications. However, these benefits are easily and accurately attributable to simply getting out of negative energy balance. What we’re observing are the benefits of switching to a maintenance phase; the “reverse dieting” component has virtually nothing to do with it. My argument is not that zero changes happen when one transitions from a cut to a reverse diet. Rather, my argument is that shifting to maintenance can bring some positive changes, and that reverse dieting fails to add any meaningful benefits beyond those attained from a simple maintenance phase.

When it comes to the illusions described in this section, it’s important to acknowledge that it’s very hard to objectively evaluate your own progress, especially when it comes to body composition changes that occur over relatively long time scales. As noted previously, even extremely well-trained and experienced dietitians routinely underestimate their energy intake by over 20%. Further, that 20% number comes from weight-stable dietitians simply eating what they normally eat over a short time scale, not those engaged in a dynamic, long-term process involving continuously changing body weight values, calorie targets, activity levels, and food choices. When you’re assessing your own progress during a reverse diet, the inflation of energy intake in the absence of extra weight gain appears to provide very compelling evidence of dramatically increased energy expenditure. It’s an illusion, but a very convincing one that just about anyone would embrace. 

With this in mind, I have heard many anecdotes of people who are currently reverse dieting, and are amazed at the mismatch between their current energy intake (which they’re actively ramping up) and their current body composition. In comparison, I rarely see folks sharing the same observations several months later, or during their subsequent weight loss diet. Energy intake is transitory, but body composition is cumulative; over time, the net energy surplus finally gets an opportunity to grow, and body composition eventually catches up to reflect the high calorie intake that was reached in the reverse dieting process. Furthermore, thrifty individuals should expect to experience drops in energy expenditure when the next weight loss diet starts, no matter how high it ramps up between diets.

A Better Alternative to Reverse Dieting

This section is going to sound like a sales pitch for MacroFactor, and that’s a bit unavoidable. We built MacroFactor to resolve diet-related challenges, and it’s important for articles on this website to clearly describe how we constructed a solution for the topic at hand. However, before I propose an alternative to reverse dieting, I want to make one thing perfectly clear: this solution is implemented in MacroFactor, but it doesn’t require MacroFactor. You can still use the information in this section without ever spending a penny on MacroFactor, and that’s totally fine by us.

With that out of the way, here’s how MacroFactor works:

You’ve been in a deficit for a while, you just reached your weight loss goal, and you want to maintain your current weight for a while. MacroFactor has been continuously calculating and adjusting a running estimate of your TDEE, so it’s very easy to estimate how large your initial calorie increase should be. However, this is just a starting point, because MacroFactor utilizes what we call “dynamic maintenance.”

For reasons previously discussed, it’s quite likely that your TDEE may increase after transitioning from a calorie deficit to approximately neutral energy balance. If this occurs and your energy intake remains stable, body weight will start to dip a little bit. You may not notice it in your daily weigh-ins, but MacroFactor’s weight trend function should be able to detect even subtle weight changes quite quickly (without overreacting to transient fluctuations, of course). If TDEE starts ramping up (and body weight starts trending slightly downward), your calorie target will increase to keep your body weight where you want it to be. In other words, MacroFactor’s energy expenditure algorithm takes the guesswork out of the initial increase, its weight trend feature takes the guesswork out of interpreting very subtle weight changes, and its dynamic adjustments for your calorie target accomplish everything that reverse dieting intends to accomplish. All without requiring unsustainably rigid, tedious, and stressful nutrient tracking practices, and without the big “leap of faith” of reverse dieting, in which you ramp up calories and simply hope that energy expenditure will follow along for the ride. 

Again, this “dynamic maintenance” approach can absolutely be done without MacroFactor. We simply designed MacroFactor to enable more confident adjustments and more rapid responses to small changes in your weight trajectory.

Is There Ever a Reason to Try Reverse Dieting?

In 2014, I was cautiously optimistic about reverse dieting. As more research has come out, I have drifted toward skepticism. I haven’t seen any directly relevant research to confirm its efficacy, and the most relevant research available provides contradictory rather than supporting evidence. For this reason, MacroFactor does not have a dedicated “reverse dieting” setting or goal category. If supporting evidence becomes available, and reverse dieting proves to be efficacious, we’ll be happy to include it. However, based on a thorough assessment of the currently available research, the costs seem to outweigh the benefits.

Having said that, not all “costs” are equal in terms of severity and magnitude. Reverse dieting is not dangerous, but there are still some non-negligible downsides involved. For people who are lean enough to be experiencing hormone-related side effects of low body-fat levels, the scientific evidence suggests that reverse dieting fails to facilitate their reversal. However, the costs of reverse dieting also extend to less extreme applications. Reverse dieting tends to be a pretty active, “hands-on” process that promotes extreme dietary precision (if adding 10 grams of carbohydrate is supposed to be a physiologically important dietary intervention, what happens if you miss your daily carb target by 5, or even 10 grams?). Speaking from experience, trying to adhere to macro targets with this level of unwavering precision is an exhausting process. Furthermore, we have no reason to believe that any increases in TDEE during a reverse diet will persist into future weight loss attempts, or will be meaningfully larger than simply shifting to maintenance instead of reverse dieting. In many cases, reverse dieting ends up being a long, tedious, effortful process that fails to deliver on its hyped up claims. In other words, reverse dieting carries a high risk of spinning your wheels and wasting precious time and effort, all to be underwhelmed and discouraged by the end result.

Based on the high potential for costs and low potential for meaningful benefits, it’s probably obvious that I’m not an advocate of reverse dieting. From my perspective, simply shifting to maintenance for a while should deliver the same benefits, while allowing a much more relaxed and stress-free approach. However, there are many folks who have heard promising anecdotes and want to give it a shot. This dietary strategy could be a waste of time and effort, but it’s not inherently dangerous, so we (the MacroFactor team) don’t think we should deprive people of the opportunity to try it. So, we specifically designed MacroFactor in a way that enables reverse dieting, without hyping it up or overstating its potential.

If you want to try reverse dieting in MacroFactor with a coached or collaborative macro program, simply change your goal to weight gain, set a fairly large weight gain goal (>10-15 lbs or so) to ensure that a transient blip in water weight won’t inadvertently bump you over the set goal weight, and select the slowest possible rate of weight gain. This should exert a slight upward pressure on your calorie recommendations, which will prompt very small calorie increases that will keep body weight fairly stable. If TDEE is staying relatively stable and you’re gaining weight at the exact rate you selected, without the need for continuous calorie increases, then it’s unlikely that any adaptive increases in TDEE are occurring. In other words, you’re not in a physiological state that would enable you to meaningfully benefit from a reverse dieting strategy, and you should probably switch to a maintenance goal. 

On the other hand, if MacroFactor is slowly but consistently increasing your calorie target over time, TDEE is likely increasing as intended. The algorithm will be attempting to promote extremely slow weight gain, so MacroFactor will continue to slowly add calories to your weekly targets if your TDEE keeps increasing. Of course, this adaptive potential is inherently limited; everyone will eventually reach a point where this adaptive capacity is maxed out. When you reach this point, you’ll observe that TDEE is staying relatively stable and you’re gaining weight at the exact rate you selected, without the need for continuous increases in calorie targets. Once this point is reached, you should probably switch to a maintenance goal. 

Personally, I think the most justifiable reason to try reverse dieting is the following scenario: you recently finished a fat loss phase, you’d like to maintain your weight loss in the long term, your energy intake at the end of your fat loss diet is a bit unsustainable for you (i.e., lower than you’re comfortable with), and you don’t have a good estimate of your true TDEE. In such a scenario, guessing your TDEE (and, by extension, maintenance calorie target) could result in a substantial overestimation, which could cause some unwanted weight gain. As such, you might want to methodically increase your calorie intake until you “find” your maintenance calorie level, which will be equal to your TDEE, without running the risk of unintentional fat regain. 

If you use MacroFactor, this scenario doesn’t apply. We provide nuanced data visualization and insights that enable you to keep an eye on your TDEE and estimate the magnitude of metabolic adaptation in real time during your diet. MacroFactor users need no guesswork to determine their first calorie adjustment when switching from weight loss to maintenance; they can effectively take a “shortcut” straight to an appropriate maintenance target, thereby avoiding the tedious and time-consuming process of reverse dieting. However, if you aren’t using MacroFactor, I think this is a very justifiable application of reverse dieting. It’s very unlikely to provide any metabolic benefits beyond a standard maintenance phase, but it allows you to reduce the risk of overshooting when you’re unable to accurately estimate your TDEE at the end of a weight loss diet. 

What About Conflicts of Interest?

I’m well aware that you’re reading this article on a website that exists to promote the MacroFactor diet app. With that in mind, I fully understand why you might have suspicions about potential conflicts of interest. So, let’s lay all the cards on the table.

As a researcher, I benefit from the idea of reverse dieting “working” as it’s commonly marketed. To the best of my knowledge, I was the first person to introduce the concept within the peer-reviewed literature. To be clear, I didn’t claim that it works, but I explained how people tend to approach it, and what it’s supposed to accomplish. I presented the idea in an open-ended manner, with no claims that it works or fails to work. Nonetheless, if you’re the first person to acknowledge a strategy in the literature, you tend to look pretty good if it turns out to be an effective strategy. This isn’t the type of thing that dramatically impacts a scientific career, but as a researcher, I only stand to lose from publicly casting doubt on reverse dieting. But here we are.

As a co-creator of MacroFactor, I could absolutely benefit from the idea of reverse dieting “working” as it’s commonly marketed. Reverse dieting would be an extremely easy feature to implement, and it would enable us to jump on the bandwagon of marketing a magical strategy that makes it easier to lose weight and maintain your fat loss. 

If you peruse our publicly available release notes, you’ll see a very clear commitment to rapid and consistent feature updates. If you peruse our publicly available development roadmap, you’ll see a very clear commitment to transparency and openness to user feedback in our development process. We have a strong track record of working tirelessly to deliver a comprehensive and effective set of features to our users, and I’m not aware of a single direct competitor that can match us in terms of the pace and transparency of development. 

In other words, there is empirical evidence confirming that we are eager and able to provide substantial feature updates that are far more challenging and resource-intensive than rolling out a reverse dieting feature. We aren’t neglecting to implement a reverse diet feature because we’re unable to design one or unwilling to improve our product; it actually would have been quicker and easier to just roll out a reverse diet feature than to write this article. We’re simply unwilling to market unsubstantiated claims driven by hype rather than scientific evidence, and unwilling to sell false hope and empty promises that may cause our users to needlessly spin their wheels without fruitful returns for their efforts. It’d be profitable, but it would directly oppose our aim and mission as a company.

Finally, just to reiterate – this article proposes an alternative approach (dynamic maintenance) that MacroFactor implements, but the approach itself does not require MacroFactor. If this article helps you achieve your goals by providing a more flexible, more evidence-based solution than reverse dieting, then it achieved its intended purpose, whether or not you ever spend a penny on MacroFactor.

Conclusions

Reverse dieting has received a lot of hype and attention, but the evidence to support that hype is severely lacking. While it sounds like an exciting new strategy, it’s usually just a simple maintenance phase with a slight upward pressure applied to daily calorie targets. Importantly, there’s no evidence to suggest that this upward pressure actually does anything worthwhile, or that reverse dieting accomplishes anything more than a maintenance phase with a dynamic calorie target.

When we launched MacroFactor, plenty of people asked why we don’t have a “reverse diet” goal or mode of operation in the app. The answer reflects our values, principles, and mission: we aim to deliver a powerful app that delivers best-in-class features and analytics, while prioritizing transparency and delivering on every single promise we make. We aren’t willing to deliver a feature that hypes up reverse dieting or overstates its utility in the absence of scientific evidence. That type of feature might be nice for marketing, but we believe it would deliver underwhelming results that fall short of the hype, and lead some of our users to “spin their wheels” in a reverse dieting phase that fails to yield tangible benefits. 

Once there is good evidence to convincingly support the efficacy of reverse dieting, it’ll be in the app. Until then, we believe that the dynamic maintenance strategy is far more compatible with the scientific evidence. Folks who are curious about reverse dieting are more than welcome to give it a shot: by simply setting a very slow weight gain goal, the basic functionality of a reverse dieting feature is easily achieved in MacroFactor.

Summary

• Reverse dieting is often touted as a remedy for metabolic adaptation, and a strategy to facilitate easier and more sustainable weight loss
• Reverse dieting was originally driven by industry marketing rather than scientific evidence. The available research casts considerable doubt on reverse dieting
• Metabolic adaptation is temporary, and it is reversed by getting out of a calorie deficit and restoring fat mass to baseline levels. It is not a long-term adaptation that meaningfully persists after weight regain
• Metabolic adaptation provides some extra friction during weight loss, but it’s certainly not an insurmountable roadblock. This friction can typically be overcome by making relatively minor adjustments to your calorie target or weight loss timeline
• Low metabolic rates at baseline do not appear to predict greater future weight gain or greater challenges during weight loss
• People who experience greater metabolic adaptation, and therefore experience slightly greater resistance to weight loss, tend to have higher energy expenditure at baseline (immediately prior to weight loss)
• Reverse dieting appears to delay recovery from metabolic adaptation after aggressive dieting phases
• People who are more likely to be dieting (i.e., people who are susceptible to efficient fat gain) are less likely to experience increased energy expenditure in response to increases in calorie intake
• People who experience greater magnitudes of metabolic adaptation (i.e., people who are most interested in reverse dieting) are less likely to experience increased energy expenditure in response to increases in calorie intake
• Weight-reduced individuals, whether they lost weight recently or long ago, are especially susceptible to efficient fat gain when calorie intake increases
• Reverse dieting doesn’t seem likely to prevent future weight regain or facilitate a smoother transition to a maintenance phase
• People who are most susceptible to metabolic adaptation seem to have higher, not lower, energy expenditure at baseline, which contradicts the concept that they need to build up their metabolic rate to make their next diet easier or more successful
• Even if the people most susceptible to metabolic adaptation were able to increase their energy expenditure through reverse dieting (which is unlikely), research indicates that energy expenditure would promptly drop when they started their next weight loss diet. So, even if gains in energy expenditure were achieved, these transient gains should be quickly lost and confer no persisting benefit. 
• We should be aiming to quantify and account for metabolic adaptation, not aiming to totally prevent or counter it via reverse dieting
• There are several very convincing illusions that make reverse dieting seem more effective than it is
• There’s no evidence to suggest that reverse dieting accomplishes anything more than a maintenance phase with a dynamic calorie target
• A “dynamic maintenance” approach should deliver the exact same benefits as reverse dieting, but in a much easier process that is less rigid, tedious, and stressful