Misleading Conclusions About Psychiatric Meds and Weight Loss - Part 1

Studying the Studies

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I recently spoke to the Department of Psychiatry at the University of Colorado School of Medicine. During talks to healthcare practitioners, I always include examples of research with misleading conclusions around weight and health. For this talk I wanted to discuss something psychiatry-specific. Unfortunately I didn’t have to look far.

I first found information about Wharton, Kuk et. al.’s study “Effectiveness of a Community-Based Weight Management Program for Patients Taking Antidepressants and/or Antipsychotics” in the online version of US Pharmacist, which bills itself as both “The Leading Journal in Pharmacy” and “The Pharmacist’s Resource for Clinical Excellence.”

The headline read “Psychiatric Drugs Aren’t Barriers to Success in Weight-Loss Program,” and the piece went on to explain that the study “provides evidence that patients on antidepressants and/or antipsychotics can effectively lose weight if they participate in a weight-management program.”

It quoted the lead author as saying “The results of this study are relevant not only to the healthcare professionals providing care to those who have both excess weight and mental illness, but also to the patients who experience these comorbidities themselves,” (more about this in part two.)

What it didn’t say, is what the study actually found. It turns out, the actual numbers of how many people lost how much weight were fairly elusive. I found the study’s stated conclusion, “Results of this study suggest that those who participate in a weight management program can lose significant amounts of weight regardless of psychiatric medication use,” in articles all over the place, but failed to find any actual hard numbers. How many of the patients lost weight? How much weight was lost? Over what time period? That information was not forthcoming.

I was able to access the abstract on pubmed which included that same stated conclusion. The “results” section, gave some clues to the fact that their definition of “significant” weight loss is…not a lot of weight loss (bolding is mine):

”Twenty-three percent of patients were taking at least one psychiatric medication. Patients lost a significant amount of weight (P < 0.0001) regardless of psychiatric medication use. Women taking psychiatric medications lost a similar amount of weight as women who were not (P > 0.05). Conversely, men taking antidepressants lost only slightly less weight than men taking both classes or neither class of psychiatric medication (3.2 ± 0.3 kg vs. 5.6 ± 0.9 kg and 4.3 ± 0.1 kg; P < 0.05). However, taking psychiatric medications that cause weight gain was associated with similar significant decreases in weight as taking medications that are weight neutral or associated with WL for both sexes (P > 0.05).” [emphasis mine]

So, this doesn’t seem like a lot of weight loss, but we still don’t have full information on what percentage of the subjects lost how much weight. It turns out, that information was behind a paywall. So I bought the study (thanks paid subscribers!) and dug in.

What I found was that, over an average of 15.8 months, “27.6% of patients lost ≥ 5%, and 10.1% lost ≥ 10% of their initial weight.”

That’s not a high percentage of people, and that’s not a lot of weight loss, and that’s far from the only issue with this.

One of the first things I always look for in studies like this is dropout rate. In this case the authors note that there were originally 29,093 potential participants but 9,454 people were excluded because they “did not attend a follow-up appointment.”

Drop out rates are something that often get ignored in weight loss research, which is a serious issue. Did those who dropped out “comply” but fail to lose weight? Did they find the side effects of the program unbearable? If the authors really wanted to be honest about the “success” rate of this weight loss program, these issues would be discussed in the paper. Instead (as is almost always the case with weight loss research) those who dropped out are simply ignored, and conclusions are drawn as if almost a third of the original sample didn’t exist.

At this point I want to mention that the study was published in “Ob*sity”* which is “the official journal of The Ob*sity Society.” I have serious issues with this organization of self-described “professionals collaborating to overcome ob*sity” which are beyond the scope of this article, but I think it’s telling that when you access the paid article you are first shown a full-color, full-page advertisement for multiple paid programs put on by these “professionals” that you have to scroll past to read the study you purchased.

The disclosures section tells us that many of these researchers are receiving money from companies that sell weight loss including Novo Nordisk, which has been engaging in massive weight-stigma-for-profit scheme.

“Disclosure: SW reports payments from Novo Nordisk, Eli Lilly, Janssen, and Astra Zeneca for advisory work. VHT reports payments from Sunovion, Shire, Novo Nordisk, and Valent for talks and/or advisory work. RAGC was employed as the Research Coordinator at the Wharton Medical Clinic and is currently working with Novo Nordisk in a research capacity. The other authors have no competing interests to report”

Then there is the fact that the idea that losing 5-10% of one’s body weight represents a “significant” amount is, at best, extremely questionable. They also fail to discuss that research shows that almost all of these people are likely to regain any weight they lost.

For me, the pièce de résistance of misleading information is this line:

“Indeed, while the overall amount of weight loss achieved in this sample was modest (3.4 kg or 2.9%), this is consistent with 3% achieved on average from long-term lifestyle interventions”

My translation of which would be: weight loss doesn’t really work for anyone, so our conclusion is that it works for everyone! This is very often followed by: I (or the organization that pays me) have this weight loss program to sell you…

This is what passes for “science” in weight loss research. Some fraction of subjects losing a few pounds short-term (that they are almost certain to regain) translates in the published results to be “those who participate in a weight management program can lose significant amounts of weight regardless of psychiatric medication use.” That, then, gets reported out in medical publications as “patients on antidepressants and/or antipsychotics can effectively lose weight if they participate in a weight-management program.”

I want to say that this is the kind of stuff that you learn not to do on the first day of your first research methods class, but I feel like even if you missed that day, they would still expect you to know better than this.

In part 2 we’ll explore the real-life patient/practitioner impacts of this kind of misleading research.

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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 Belly of the Beast: The Politics of Anti-Fatness as Anti-Blackness for more on this.