Does This Study REALLY Prove There Is No Harm from Weight Cycling? Part 1 - Authors and Introduction

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I’ve had more than one hundred requests to write about this study so here we go!

Discussions about research on the dangers of weight cycling (losing weight and then regaining it) have been going on since before I was born. I’ve written about it specifically before. This is especially important given that the vast majority of intentional weight loss attempts result in weight cycling.

As more data has come out about the realities of GLP-1s for weight loss (including some people regaining weight while still taking the drug, and research showing that those who go off the drugs regain weight quickly, paired with their own research showing that by year four, 89.5% of patients were no longer on the drug,) there has been talk about the dangers posed by drug-induced weight cycling. As we’ve seen with other concerns around these drugs and intentional weight loss in general (like eating disorders,) suddenly I’m seeing articles and studies trying to minimize the concerns about weight cycling.

Enter “The Physiological Effects of Weight-Cycling: A Review of Current Evidence” published January 3, 2025.

As usual, I’ll start with the authors. They claim no conflicts of interest, and they are an interesting group.

Nora Sanaya is the first listed author.

Per her LinkedIn she was “recently hired” as a “Merchandise Project Manager | Universal Music” She has a “bachelors degree in Food Science & Nutrition from the University of Copenhagen” and her linked in lists Nestlé and Novo Nordisk as companies she is interested in.

She previously worked for Novozymes (now Novonesis) as a Student Assistant. Novonesis’ controlling shareholder is the Novo Nordisk Foundation

Monika Janusaite’s LinkedIn shows that she is a student worker in Regulatory & Scientific Affairs at Nestlé and a MSc student in Human Nutrition at UCPH

Novo Nordisk’s President and CEO, Lars Fruergaard Jørgensen, is in her “Top Voices” on LinkedIn

Maria Dalamaga

Is a Clinical Pathologist and Professor at the Medical School, National & Kapodistrian University of Athens.

She doesn’t have any conflicts of interest that I could find, but she does some research around pathologizing fatness.

Faidon Magkos

Professor of “Ob*sity” and Metabolism at the University of Copenhagen

He is also the head of MORE2SLEEP, which studies the effect of extra sleep on weight, metabolism and learning among 6- to 9-year-old children. This project is funded by the Novo Nordisk foundation to the tune of US$3,516,907.05

The Novo Nordisk Foundation also funded his workshop (Note - link leads to extreme weight stigma) and article ”On the pathogenesis of ob*sity: causal models and missing pieces of the puzzle”

He spoke at a symposium put on by the Novo Nordisk Foundation at the Novo Nordisk Foundation

By the way, a quick note about the Novo Nordisk Foundation. A common misunderstanding is that Novo Nordisk has a foundation under it that funds “initiatives”, but that’s not how it works. In this case, The Novo Nordisk Foundation is the umbrella organization and the other Novo companies are under the foundation. The foundation uses the money from the companies to fund these “initiatives” (Again, link here lead to significant weight stigma.)

Interestingly, Magkos listed this relationship as a conflict of interest in other research published in 2025, so I’m unclear why, given Novo’s clear interest in minimizing/erasing the harms of weight cycling, it’s not included here.

Let’s move on to the publication itself.

This piece was published in a journal called “Current Ob*sity Reports” The editor in chief is Caroline Apovian. When l first wrote about her in June 2022 and she was shilling for weight loss drugs in the New York Times, she had taken $3,740.00 in consulting fees from Novo Nordisk. By the end of 2023 she was up to $68,843.06 in general payments from Novo Nordisk and another $11,070.16 in associated research funding. We don’t yet have the 2024 numbers. We do know that she ha still been shilling for Novo Nordisk in the press.

I’ll start with their purpose, findings, and summary claims. The text that is indented and in italics are from the study, you can skip them and in so doing you’ll skip a bunch of weight stigma but you’ll still get the gist.

Purpose of Review There is a common perception among the public that yo-yo dieting, defined as repeated cycles of weight loss followed by weight regain, results in accumulation of fat in the body and lower metabolic rate, thus hindering subsequent attempts to lose weight. We evaluated the effects of weight-cycling on body weight and body mass index (BMI), body composition including fat mass (FM) and lean body mass (LBM), and resting metabolic rate (RMR), by systematically reviewing existing scientific literature.

Right away we see that they are myopically obsessed with weight/weight gain as if that’s the only harm that could come from weight cycling. In fact, the concerns around weight cycling are that it is, by far, the most common outcome of weight loss attempts and it has been correlated with a host of negative health impacts, many of which get blamed on higher-weight, including, but not limited to, increased inflammation, insulin resistance, hypertension, cardiovascular disease, and increased overall mortality. These authors aren’t worried about those, though - they chose only to study if one incidence of intentional weight loss that turns into weight cycling is likely to hamper future attempts at weight loss (the vast majority of which are likely to become weight cycling.) That’s far from the only issue with this study.

Let’s look at their findings

Recent Findings Twenty-three cross-sectional and cohort studies (including subjects with a history of weight-cycling compared to those without such history) and interventional studies (evaluating physiological effects during one or more cycles of weight loss and regain) were identified, conducted in generally healthy adults across various age groups, races, and both genders, who had normal weight, overw*ight, or ob*sity. Eighteen studies investigated the association between weight-cycling and body weight or BMI, and thirteen of them found no significant association. Fifteen out of twenty studies also found no increase in FM, and none of eighteen studies found a decrease in LBM. Twelve out of fourteen studies reported no adverse changes in RMR either.

I first want to note that there is no trans or nonbinary representation here and, in fact, their language erases trans and nonbinary people. Even if there weren’t issues with these studies (and there are many, and we’ll get to them) this would still be an issue. Five of 18 studies (about 28%) found an association between weight-cycling and body weight or BMI. 5 out of 20 studies (25%) found an increase in fat mass and 2 out of 14 studies (14%) found adverse changes in resting metabolic rate. From here they conclude:

Summary The overwhelming majority of evidence suggests that weight-cycling (yo-yo effect) is not associated with any adverse effects in body weight, body composition, and metabolic rate. Accordingly, healthy individuals who struggle with ov*rweight or ob*sity should not be discouraged from repeated attempts to lose the excess weight.

I’m not sure I would characterize 72%, and 75% as an “overwhelming majority,” but even if we accept that, the claim in the second sentence of the summary is not remotely appropriate based on their data. First of all, there were studies that did show “harm” (even in the very limited ways that they are defining it) so they would have to at least be able to show success and subsequent benefit for weight loss attempt in excess of those potential harms. Otherwise people are attempting a weight loss intervention that has a 28/25/14% chance of various harm with no likely benefit.

Beyond this, their conclusion cannot be appropriately drawn from their data. The idea that this research shows that “healthy individuals” (which would require an operational definition to be a useful concept here) should not be discouraged from weight cycling can only be claimed if one is ignoring or ignorant of the many negative health impacts associated with weight cycling. If these authors are ignoring those potential harms then they are not ethically competent to conduct this research and draw these conclusions. If they are ignorant of these potential harms, then they are simply not competent to conduct this research and draw these conclusions. That said, they mention that they specifically excluded 21 articles from their review because they “investigated aspects of weight cycling other than body weight, body composition or RMR,” so it seems like they may have been aware.

Those are some basic issues, but it actually gets much worse! In Part 2 we’ll dig into the studies that they analyzed.

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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’