If Weight Loss Is A Prescription

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Weight loss is treated by many healthcare providers as a healthcare intervention. In situations where they would prescribe other treatment protocols, including pharmaceuticals, for thin people, they often “prescribe” weight loss to fat* patients. But does weight loss meet the basic requirements of ethical evidence-based medicine - Does it work and is it safe?

Note that for this article when I talk about weight loss interventions I’m talking specifically about those that involve food and/or movement. I have separate articles about weight loss drugs and weight loss surgeries.

Does it work?

The idea that weight loss “works” is largely based on three things: short-term studies, manipulation of the term “significant,” and blaming the people for whom it is unsuccessful.

Short-term studies

The long-term research that we have shows that most people lose weight short-term (in the first year) and gain it back long-term (years 2-5.) Perhaps because so much of it is funded (and sometimes conducted) by people with a profit interest in weight loss, most weight loss research is two years, at best. Short-term studies (those that are a year or less) often show a little bit of weight loss. Then the study is stopped and we are to believe that if people can lose a little bit of weight short-term, they can lose a much larger amount of weight long-term. Studies that stop at two years typically show that people lose weight in the first year, gain part of it back in the second year, and then the study’s conclusion says something like “everyone remained below their starting weight,” hoping (very often successfully) that people, including healthcare providers, will assume that the weight gain stopped the day the study stopped tracking the subjects.

Considering the research that shows that weight is typically regained after two to five years, if the weight loss method being prescribed doesn’t show sustained weight loss after five years, then there is no reason to believe in the efficacy of the weight loss method.

Manipulation of “significant”

The idea of what constitutes “significant” weight loss has been manipulated in a couple of ways. First, through attrition of the amount of weight loss that, it’s claimed, leads to health benefits. This began with very strict height and weight tables, then became 20%, then 10%, then 5%, and now we’re seeing people say that even 3% weight loss creates “clinically meaningful” health benefits. But don’t let the word “clinically” fool you, this number is based on the failure of dieting, not clinical results. In their 2013 paper, Tomiyama, Ahlstrom and Mann said it this way

  “only 5% of ob*se* dieters succeeded by that definition (Stunkard & McLaren-Hume 1959) Over the next 30 years, reviews of diet studies showed that individuals tended to lose an average of about 8% of their starting weight on most diets. In an effort to create a move achievable goal, but without any particular medical reason, researchers lowered the standard to just 5%.” [emphasis added]

Their paper analyzed these claims of small amounts of weight loss leading to health benefits and found that “In correlational analyses, however, we uncovered no clear relationship between weight loss and health outcomes related to hypertension, diabetes or cholesterol, calling into question whether weight change per se had any causal role in the few effects of the diets.” I wrote about this more extensively in this piece.

The other manipulation of significant is a misuse of the concept of “statistical significance.” When a study looks at an intervention’s outcomes and find that those outcomes are “statistically significant” it simply means that it is more likely that the outcomes are a result of the intervention than that they were the result of chance. So if a study had a statistically significant finding that people using some weight loss method lost 3% of their body weight, that would mean that it was more likely that the small amount of weight loss was due to the weight loss method than that it was by chance. However, if the study conclusion were to say that people lost a “significant amount of weight” when what they meant was that the weight loss was statistically significant, they might mislead people into thinking that “significant” in this case meant “a lot of” weight. This study seems to be an example of that.

The Blame Game

Sometimes people know all of the information above still peddle weight loss interventions based on the claim that it’s not that the weight loss interventions failed, it’s that the people did. First of all, even if it was true that 95% of people just aren’t able to get it right, that would still be an issue that, in at least a century of research, those outcomes have not been improved. However, research shows that these intentional weight loss attempts cause the body to change in ways that, essentially, make it a weight-regaining, weight-maintaining machine. I talked about this more in-depth here.

The bottom line here is that the research that exists only supports the idea that most people can lose a small amount of weight short term that they are likely to gain back, and that is unlikely to produce health benefits. This calls the efficacy of these weight loss interventions into serious question and a healthcare practitioner who isn’t clear about this (who, for example, says that anyone who tries hard enough can lose weight) is not fulfilling the requirement for informed consent.

Is it safe?

So, research shows that weight loss interventions are unlikely to be successful, but what about their safety. Unfortunately, it’s not just that they fail, but that failure can do serious harm. In fact, the weight cycling that is, by far, the most common outcome of weight loss interventions is independently linked to many of the health issues that get blamed on fat bodies as well as increased overall mortality. In fact, in their 2011 paper Bacon and Aprhamor found that weight cycling could account for all of the excess mortality that was blamed on “ob*sity”* in both Framingham and the NHANES. I wrote more about this here.

And that doesn’t take into account the psychological harm of believing that it was your fault that that the weight loss intervention failed, or the psychological impact of regaining weight after the massive amount of praise that people receive for weight loss (which is likely heightened if they talked/posted about their weight loss publicly as many people are encouraged to do.)

Then there is the harm that happens when fat people are given a “prescription” for weight loss when thin people would be given other interventions, which results in delayed care and possible advancement/increase of the health issue during the (possibly years) that the person is trying (and failing) to lose weight.

With no evidence to suggest that intentional weight loss interventions produce long-term significant weight loss or health improvements (two separate things,) and evidence and lived experience telling us that they, in fact, often result in harm, I do not believe that weight loss interventions meet the requirements of ethical, evidence-based medicine.

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More research and resources:
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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’s Belly of the Beast: The Politics of Anti-Fatness as Anti-Blackness for more on this.