Three Easy Ways to Know If A Diet Study Sucks

LiesOne of the most frustrating things about weight loss (so-called) research, is that the media often covers any weight loss study as if the conclusions they claim have been proven beyond a shadow of a doubt when, in fact, much of the research is embarrassingly poor – often for profit by the weight loss industry. I get a lot of questions about how to evaluate studies, and it’s a topic that can get complicated fast, but here are some easy ways to evaluate a study about a purported weight loss technique

1. Did they take their time?

This is covered in greater detail here, but basically almost everyone can lose weight short term, but almost everyone gains it back within five years. So if a study doesn’t follow subjects for at least 5 years then it’s not a valid look at whether a weight loss method works for anything more than the short term.  (This is especially important with diet companies like Noom which both claims to be a “brand new” way to diet, and simultaneously claims that they offer “permanent” weight loss. Where are they getting their long-term data? If they are “brand new,” how many people who lost weight on their program could have died having kept it off?

2. Are these people?

When it comes to the study subjects, you might think that you should start with questions like “were the study participants diverse?” But you actually need to start with the question “were the study participants human?”

I can’t even count how many times that I’ve read an article about a study and asked myself “Wait – were  this rats?” and then looked it up to find that it was, in fact, done with rats as subjects. And the reporter didn’t bother to mention that while droning on about how effective this new diet is. (pro-tip – if they only talk about them as “study subjects” and they only talk about weight lost as a percentage of overall body weight and they never mention “pounds” they might be rats.)

3. Who are these people?

If the researchers did study humans, we then have to ask how representative the sample  (the group of people who participated in the study) is. Which is to say that who they study determines to whom the study results can be appropriately extrapolated. So if they only studied white cisgender dudes, that’s the only group we can expect the results to apply to (and that’s only if they had a large enough sample – included enough white cisgender dudes – to rule out individual differences.)

A number of assumptions in medicine that have been proven false (like the idea that heart attacks have the same symptoms regardless of gender) were based on researchers’ habit of studying 150-pound cisgender white men and then extrapolating those results to literally everyone. Many studies (not just weight loss, but all studies) under-represent People of Color and completely fail to represent Trans and Non-Binary people at all. Representative samples are a huge issue, and that’s not even getting into the variables they don’t control for. So you are looking for a study with a large, diverse sample.

To date, there is not a single study where more than a tiny fraction of people were able to maintain significant weight loss long-term, so don’t be suprised if you find the weight loss studies you are analyzing are lacking in study methodology, and subject success.

If you are interested in checking out an exhaustively researched paper supporting a departure from diet culture, I recommend you head over here.

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8 thoughts on “Three Easy Ways to Know If A Diet Study Sucks

  1. Weight loss, the great leveler. Smallest studies possible to cover/advertise to largest consumer populace. Most money=least results, still A.O.K. when the topic is adipose tissue… The “Sure, we all do.” of the advertising world. Here is a sick question. Has ANY weight loss scheme, product, offering ever lost money? I mean over all? Even ones proven to be fatal will have reaped enough cash to count as a win before they are pulled from the shelves (only to be re-discovered, re-packaged and re-sold 10-15 years later).
    I have to wonder if anything else garners such viable and enthusiastic usage? Erection disorder fixes come to mind; but if a side effect was penile-sloughing I can’t imagine the fallout. Instant recall, shelves stripped, emergency reversal medication, congressional hearings, class action suits, stock holders exposed and having to flee the country. Company name tarnished permanently, left over medication sold to “third world” nations as wart remover.

    1. I still like the one that claimed fat people were more likely to be in poor health than thin people, only when you actually read how they were defining poor health, it turned out they were defining poor health as “having a large waist.”

      Quite the polemical stance, that fat people are more likely to have large waists than thin people.

      1. I remember both of those! I read a big, long article about how intentional weight loss doesn’t work long term, doesn’t really work for *enough* weight loss to make the differences that are promised, and causes long-term weight gain, due to yo-yoing, and yet, at the end, the person writing the article said, we should all (yes, all), STILL try to lose weight. Because even the anorexics and “underweight” people “could always do with losing a few pounds.”

        WHAT?!?!?!?!?! You just reported how BAD it was to try to lose weight, and then you 1) completely ignored the existence of people for whom ANY sort of weight loss would be a very bad thing and quite possibly fatal in the short term, and 2) encouraged fat people to lose weight, JUST BECAUSE, despite all the dangers you JUST TOLD THEM ABOUT!!!

        And then that “poor health” equals “large waist” study. Oh, my stars and garters!

        Hey, remember the one about how babies as young as six months can tell the difference between “fat” people and “attractive” people? From silhouettes? Yes, that was the spectrum they used. Fat on one end, and “attractive” on the other.

        1. THAT “STUDY” ZOMG! XD I totally remember that, not just because the research was just as trustworthy as you’d expect… but because its results showed the babies preferred the “unattractive” fat bodies! Bogus as the data is, I would still qualify it as a self-own. Those fatphobes were basically making their data up and it STILL failed to support their premise.

  2. Another thing to consider: Who is paying for the study? I can’t find the link, now, but I remember one study about the benefits of a low-fat diet, paid for by a margarine company.

    Hmmmm… Biased, much?

    1. Remember that meal replacement shake manufacturer’s study that found out the safest and most reliable diet is a VLCD composed of meal replacement shakes? Welcome to the world of “obesity” “treatment,” where ALL the henhouses are guarded by foxes.

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