Study Claims No Harm from Weight Cycling Part 3 - Conclusions

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The study “The Physiological Effects of Weight-Cycling: A Review of Current Evidence” published January 3, 2025 is making broad claims that “healthy individuals who struggle with overw*ight or ob*sity should not be discouraged from repeated attempts to lose the excess weight.” In part 1 we looked at the issues with the authors and the premise. In part 2 we looked at the issues with the studies they included, in this final part we’ll discuss the issues with their interpretation and conclusions.

As with the other pieces, direct quotes from the study are in italics and indented. You can skip them and still get the gist of the commentary.

Now, the authors aren’t unaware that there are issues with the studies on which they are basing their conclusions. They admit:

We identified some limitations in the reviewed studies, which must be taken into account when interpreting their results. The majority of them did not consider the impact of physical activity on energy balance, body weight homeostasis, and body composition which can confound the rates of weight loss and regain, as well as the composition of lost and regained tissue mass (e.g., in relation to preservation of LBM). Lack of physical activity assessment likely represents a systematic error that is relevant to both groups (weight-cyclers and controls), as it is unlikely that one group exercised systematically more than the other.

Wait a minute - how did they decide that it was unlikely that one group exercised more than another? Here is one possible scenario - our weight-obsessed society tells people that exercise makes you healthier by making you thinner (despite strong evidence that the benefits of exercise are direct). So when people start regaining weight, they assume that exercise isn’t “working” and they quit. That’s not, like, out of the question. Regardless, they cited nothing to support a claim they are using to shrug off a potentially serious issue with their review and, as I’ve said before, just saying stuff is not appropriate research methodology.

Among the few studies that took physical activity into account, the level of physical activity was self-reported , and thus likely overestimated . In two studies on wrestlers, controls were selected to have the same self-reported level of physical activity. The study by Van Dale and Saris was the only one to incorporate exercise as a part of their intervention. Combining physical activity with dieting is an effective approach for losing FM and preserving LBM [53, 54 ]. Therefore, it is important to consider physical activity when assessing changes in body composition in relation to weight-cycling.

First of all, they are clear that something that they believe is important to consider wasn’t appropriately considered in the research on which they blithely based a recommendation that higher-weight people not be discouraged from repeated weight cycling attempts.

But there is something else I want to highlight. It’s something that happens frequently in articles like this that try to support the weight loss paradigm, they just slide an overreach into the discussion.

Claiming “combining physical activity with dieting is an effective approach for losing FM and preserving LBM” isn’t a small thing, that’s a pretty major claim. To support it, they offer two citations:

The first, “Dietary Protein and Exercise Have Additive Effects on Body Composition during Weight Loss in Adult Women” is from 2005 and was a 4 month weight loss intervention with 48 cis women aged 40–56 (it fails to include data on participants’ race or ethnicity.)

The second is “Dieting is more effective in reducing weight but exercise is more effective in reducing fat during the early phase of a weight-reducing program in healthy humans” from 2003. It included only 13 subjects, all cis women 22-55 years old. (It was a convenience sample, they were students of a nutrition class and the teacher.) Again, I could not find information on race. They participated in a two-phase crossover treatment study. Each “phase” was a 9 day diet followed by 5 day “energy repletion.”

I simply cannot imagine how someone can seriously cite these two tiny studies from 20+ years ago to support the incredibly broad claim that ”combining physical activity with dieting is an effective approach for losing fat mass and preserving lean body mass”. This is the kind of thing I expect from a pressed-for-time undgrad writing a paper and hoping their professor won’t actually check the citations. This is not something that should make it past peer review.

Certain dietary regimens have been found to lead to a greater loss of LBM than others (e.g., low-protein versus high-protein diets, respectively), with the macronutrient composition and energy content affecting the composition of lost and regained body weight and tissue mass, at least in the short term.

“At least in the short term” At least they are being honest, though when they say “short-term” they really mean it. They offer two citations for this one as well.

The first is “Effect of a high-protein, energy-restricted diet on body composition, glycemic control, and lipid concentrations in overw*ight and ob*se hyperinsulinemic men and women” It included 57 subjects (14 men, 43 women) in a 12 week diet and 4 week “energy balance”

The second “A Reduced Ratio of Dietary Carbohydrate to Protein Improves Body Composition and Blood Lipid Profiles during Weight Loss in Adult Women” included only 24 cis women ages 45 to 56 and a 1 week control period followed by a 10 week diet.

Again, this is incredibly common in weight loss research and I’m not saying it’s necessarily because researchers are doing it on purpose. It might also be that the confirmation bias is so strong that they simply don’t question what they assume to be true.

Importantly, all observational studies relied on self-reported weight history to define weight-cyclers, as well as self-reported eating (and in some cases, physical activity) habits. Self-reported data introduces a potential source of bias and inaccuracies in reporting, which can affect the reliability and validity of the findings.

They are correct here - this is a serious potential source of bias. Given that they understand this, maybe they should have backed off their recommendation a bit, instead of claiming confidently that higher-weight people shouldn’t be discouraged from doing something that has been linked with serious physical and psychological harm.

And finishing off with their conclusion:

The existing scientific literature does not provide substantial evidence for the association between weight-cycling and adverse changes in body weight, body composition, and RMR in healthy individuals.

If these 23 studies actually represent the existing scientific literature then the actual conclusion should be that there is not enough evidence to make a determination.

More well-controlled randomized human trials are needed to provide definitive evidence. While some studies suggested that weight-cycling potentially poses challenges for future weight loss, hard evidence is lacking, and further studies are needed, particularly studies that regulate or objectively measure dietary intake across the cycles and include maintenance periods after each weight loss phase. Additionally, it is critically impor-tant for future investigations to establish a more standard-ized definition of weight-cycling, in order to enable better comparison between studies.

This is accurate. It’s also where they had the opportunity to add “thus, we cannot ethically and responsibly make a recommendation” and call it a day, but they did not.

To conclude, and although we did not consider the effects of weight-cycling—if any—on metabolic function and cardiometabolic risk factors, con-sidering the current limitations in weight -cycling research and the weight of evidence pointing away from any adverse effects of weight-cycling on body weight, body composi-tion, and energy expenditure, individuals who suffer from overweight or ob*sity should not be discouraged from their weight loss efforts.

In part 1 you might remember that I said that one can only claim that this research shows that “healthy individuals” (which would, of course, require an operational definition to be useful) should not be discouraged from weight cycling if one is ignoring or ignorant of the many negative health impacts associated with weight cycling. If these authors are ignoring those issues then they are not ethically competent to conduct this research and draw these conclusions. If they are ignorant of the research then they are simply not competent to conduct this research and draw these conclusions.”

Well, it turns out they are not ignorant of the issues.

Also note the weight-stigma-steeped phrase “individuals who suffer from overweight or ob*sity.” Speaking for myself, I’m suffering from weight stigma and a headache from having to read through embarrassingly shoddy research.

Ok, let’s sum up:

Even though (despite the study title claiming to be reviewing “current evidence”) the included studies date back to 1989 and (while I’m sad to do this math) that’s 36 years ago and almost half the studies are from the 1990s…

And even though the studies were a combination of small samples and/or short duration and/or studies that didn’t actually include any higher-weight people and/or studies that had “weight cycling” that was very different than typical real-world scenarios…

And even though they chose to only consider body composition and metabolism, despite being aware of research associated weight cycling with significant physical and psychological harms, including increased overall mortality…

And even though their analysis is not remotely strong enough to support drawing any kind of strong conclusion…

And even though they offer no refutation of the century of research that suggests that almost all weight loss attempts will just end up in more weight cycling…

They went ahead and claimed that higher-weight people “should not be discouraged from repeated attempts to lose the excess weight”.

Here we have another example of researchers, including those with significant ties to the weight loss industry, sacrificing the health of higher-weight people at the altar of the weight loss.

I agree with them about one thing - we need much more research about the possible physical and psychological harms of weight cycling . I would just add that it should be better than this.

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*Note on language: I use “fat” as a neutral descriptor as used by the fat activist community, I use “ob*se” and “overw*ight” to acknowledge that these are terms that were created to medicalize and pathologize fat bodies, with roots in racism and specifically anti-Blackness. Please read Sabrina Strings’ Fearing the Black Body – the Racial Origins of Fat Phobia and Da’Shaun Harrison’