IRA FLATOW: This is Science Friday. I’m Ira Flatow. Weight loss is a big business. Americans spend roughly $60 billion each year trying to lose weight, forking over cash for supplements, diet plans, gym memberships. And yet, about 90% to 95% of diets fail. Much of what we think we know about the relationship between weight and health is based on a series of assumptions, assumptions that don’t always match up with the latest science. Science Friday producer Shoshannah Buxbaum is here with a closer look. Hi, Shoshannah.

SHOSHANNAH BUXBAUM: Hey, Ira. So I’ve been listening to the podcast, Maintenance Phase, for the past couple of years, and it’s fundamentally shifted how I thought about health and nutrition research. So I recently caught up with the show’s co-host, Aubrey Gordon, to talk about her new book, You Just Need to Lose Weight and 19 Other Myths About Fat People. I started off with some basics by asking her about the history of the word, obesity.

AUBREY GORDON: Yeah, there’s this sort of ambient belief or assumption amongst folks out in the world that, obese, or, obesity, are originally medical terms because they’re currently used in medical context. They actually predate that. They have long been used to describe, basically, people who we think of as being unacceptably fat, right? The actual roots of the word in Latin literally mean to have eaten oneself fat. So it’s already aligning a fat body with gluttony, which is a deadly sin, right?

SHOSHANNAH BUXBAUM: Right.

AUBREY GORDON: It assumes a cause of their fatness. There is judgment built into the term itself, no question.

SHOSHANNAH BUXBAUM: And you also talked about, in the book, a study that looked at doctors and found that, actually, after medical school, they’re more likely to view their fat patients as either not being compliant or have all these sort of negative associations with them, which is maybe not what you’d hope after a medical school education.

AUBREY GORDON: Yeah, absolutely. There was a study of medical students that looked at of their attitudes toward fat patients and found that, throughout the course of medical school, that bias appeared to intensify, particularly because it was being modeled by professors and by older physicians who were coaching them into their roles.

There is also some research into the attitudes of physicians, who are more likely to describe their fat patients as non-compliant, awkward, and ugly, as well as unhygienic and just a series of very personal judgments that precede even meeting the patient. This is on the basis of appearance alone. And I think it’s important to note that physicians get an incredible amount of technical training in so many things. But that technical training doesn’t generally include confronting their own biases about the patients they may serve. And that’s true of fat patients, in particular.

SHOSHANNAH BUXBAUM: It directly affects people accessing health care, which is obviously a big equity issue. But I want to touch on this statistic that comes up when we’re talking about this issue a lot. And you really dive into the methodology of it in your book and also in the podcast. So this number– 360,000 to 400,000 people die from obesity every year in the US. And this number gets floated around as– we’ve got to do something about this because this is a leading cause of death. So you looked into it. Let’s dig into some methodology behind this number here.

AUBREY GORDON: Yeah, let’s do it. I’m into it. [LAUGHS] So this number– this 400,000 Americans die every year of obesity– is a number that’s been kicked around for about 20 years now. So in the research for this book, I went back and found that original paper and read the methodology section– the whole thing, but particularly the methodology section, in which the paper plainly stated that it was looking at actual death rates between thin people and fat people. More fat people died in the years that they were looking at. So that gap between deaths in fat people versus deaths in thin people– they said we’re just going to assume that that’s the result of them being fat. They didn’t die in plane crashes. They didn’t have car wrecks. Nobody got struck by lightning.

SHOSHANNAH BUXBAUM: Right. We’re going to attribute every single thing to that.

AUBREY GORDON: Right, they just got so fat that they dropped dead. I would also say, for this 400,000 number, if that many Americans were dying every year of just getting too fat, more of us would know someone who just got so fat that they died. That would be part of the conversation a little bit more. That’s because these mortality estimates vary really widely because you’re dealing with huge data sets. It’s worth knowing that this 400,000 number gets kicked around quite a bit because it is the largest one of these mortality estimates.

Those range down as far as 20,000 a year in the US, attributable to fatness. And even that might be an overreach, according to some researchers. These are highly disputed numbers because it’s so hard to get at because what we’re talking about with fatness isn’t a health condition that causes people’s death. It’s a risk factor for other health conditions that go on to cause people’s deaths. So trying to track down the mortality rates of a risk factor is a really tricky proposal.

SHOSHANNAH BUXBAUM: One of the things that people point to when they’re like, OK, like how big is this, quote unquote, “problem,” they’re looking at the BMI– the body mass index. And so it seems really simple. It’s height divided by weight– seems scientific. Then people get grouped into categories– underweight, quote unquote, “healthy weight,” quote unquote, “overweight,” quote unquote, “obese.” But who came up with this system in the first place? I think folks that don’t know the history might be a little bit surprised on how we landed on this as a categorization system.

AUBREY GORDON: Yeah, this is another one of those things like the term, obesity, where folks assume that it is medical in origin. It’s worth noting that the BMI was actually not developed by a physician and wasn’t designed for individual health care. It was designed as a population level, essentially like statistics tool. It was developed by a Belgian astronomer and mathematician named Adolphe Quetelet, who was looking for what he considered to be the, quote unquote, “ideal average man.” He wanted to figure out what the average of the human populace was so that we could all aspire to that. This was in the 1800s. So he created the BMI as one way of measuring the physical aspects of that, and he based it on the height and weight of French and Scottish members of the military in the 1800s.

Now, most of us have figured out that bodies have changed a lot since the 1800s. We’re taller. We’re fatter. Lots of things have changed. It’s also worth noting that all of those people were overwhelmingly white and overwhelmingly men. And the BMI has never actually been fully adjusted for anyone who’s not white and anyone who’s not a dude.

The BMI essentially only entered into health care provision when American insurance companies were looking for, essentially, reasons to charge some policyholders more than others. and they settled on body size as part of their ratings, and that began the path to get this wormed into individual health care provision. And now we’re at a point where this tool that was designed for population-level analysis, for a social project around finding this, quote unquote, “ideal man” now comes up on after-visit summary for patients in the US, is now considered a primary marker of individual health at a cultural level, and has been totally divorced from this history that really has nothing to do with individual health.

SHOSHANNAH BUXBAUM: If you’ve been conscious the past several decades, you’ve probably heard policymakers raising and ringing alarm bells about the obesity epidemic, so how did policymakers come together to consider this an epidemic?

AUBREY GORDON: The defining of, quote unquote, “obesity” as an epidemic starts with defining, quote unquote, “obesity” as a disease. And that actually happened through a number of major health care institutions and medical institutions in the US. The American Medical Association did this. The National Institutes of Health– a number of entities went through a process to essentially study, in each of their organizations, does obesity qualify as a disease?

And in most of those study groups, their researchers and physicians and so on and so forth came back and said, actually, we can’t really determine that because we don’t actually really have an operating definition of what a disease is. So you’re asking us to classify this thing that is a risk factor for other health conditions as being a, quote unquote, “disease” in and of itself. But we don’t really have an operating definition there, so we don’t really feel comfortable making this statement.

Those institutions then overrode the recommendations of their own study groups and their own committees and declared obesity to be a disease, in and of its self. And that paved the way for an understanding of obesity as a, quote unquote, “epidemic,” which also positions it as a contagion. When we talk about epidemics, we’re usually talking about contagious diseases. So it recast fat people as social contaminants or health contaminants. And a war on obesity, I will say, just as a person who is a fat kid and a fat adult during this time, just feels a lot like a war on fat people. It felt pretty staggeringly stigmatizing.

SHOSHANNAH BUXBAUM: Yeah, and I think, at this point in our conversation, some listeners at home might be thinking, OK, I’m here with you. This relationship between weight and health is really oversimplified. Obviously, it’s much more complicated. What about the association between weight and other health conditions like diabetes, high blood pressure, heart disease? How can you make sense of these associations that we see while not falling into the trap of an anti-fat bias?

AUBREY GORDON: Yeah, I think a couple of things are worth noting. If you’re concerned about diabetes, the best way to track that is through your blood sugar right and through regular blood work from your doctor. I would also say there are strong correlations between a number of these health conditions– diabetes and hypertension and cardiovascular disease in particular– there are pretty strong links to what’s called minority stress, which is daily experiences of racism and sexism and anti-fat bias. All of those things contribute significantly to folks’ risks for each of those health conditions.

So measure your blood sugar. Measure your blood pressure. We actually have ways of getting this information pretty easily. And we should be taking advantage of those rather than hanging everything on this existing sort of framework that we have around fatness and fat people and looking for reasons why we assume fat people must already be unhealthy.

SHOSHANNAH BUXBAUM: This is Science Friday from WNYC Studios. The myth in the title of your book is, you just need to lose weight. And this message is absolutely everywhere. It’s pushed as an easy solution to preventing any number of bad things from happening to you. I once had an abnormal result on an eye exam. I went to a specialist who said, everything looks totally fine. But before I left, he was like, you really should lose some weight. And, why is this advice of, you just need to lose weight, one, way harder to follow than it sounds, and two, also extremely harmful to fat people who are on the receiving end of this advice, constantly?

AUBREY GORDON: I would say, you just need to lose weight, is the way that people decide not to pay attention to what fat people are going through. You just need to lose weight, is the thing that I hear when I talk about being denied care by a health care provider or being escorted off a plane. If you don’t like it, you should just lose weight.

I think the first thing we forget in the, just lose weight, conversation is actually our own personal experiences. Most of us have experiences trying to lose weight, and most of those experiences have failed or have succeeded in the short term and led to longer term weight gain. The data here is strikingly consistent. And that is the overwhelming majority of diets lead to a small amount of short-term weight loss and then long-term regain, and usually a little bit more weight is regained than you started with.

So over time, paradoxically, dieting and weight cycling seem to make people fatter in the long term. That’s for a lot of reasons. One of the current theories, which comes out of a study of contestants on The Biggest Loser appears to be that going on these kind of extreme calorie restrictions in diets appears to permanently alter our metabolisms and lead folks to burn hundreds of calories less per day than their peers in the same age group. So folks who go through this kind of extreme calorie restriction their bodies sort of permanently downshift and assume that it will continue to get lower levels of energy, smaller amounts of food over time. And as a result, it stores more fat. That’s one of the theories, currently.

The other theory here that we’re learning more about is– this idea of willpower is everywhere in dieting. And increasingly, research is really clear that willpower, as such, is pretty much just a couple of hormones in your endocrine system it’s ghrelin, the so-called, hunger hormone, and leptin, the so-called satiety hormone, each of which kick in really differently when you’re dieting. Your body will signal to you to eat more if you are eating less than usual. That’s not a matter of willpower. That’s a biological mechanism to keep you alive, right?

SHOSHANNAH BUXBAUM: Right.

AUBREY GORDON: And it’s one worth paying attention to. So it’s really interesting to me that we continue to have this very personal responsibility narrative about weight loss in defiance of almost all of the available data which says, willpower isn’t really a thing. Diets don’t really work. And we don’t consistently know how to make fat people thin in the long term.

SHOSHANNAH BUXBAUM: So after each chapter in the book, you have a few reflection questions. I really love this approach to learning. So what’s some advice you can give to our listeners to help them think a little bit more critically the next time they see a news article about some new, magic diet that works miracles or some new, here’s the latest on the obesity epidemic? How can folks maybe take pause and critically reflect on this information they’re consuming?

AUBREY GORDON: My hope is that this is a welcome pointer for a Science Friday audience, which is don’t base your judgments on a headline. Don’t actually even base it on an article about a study. Go read the actual study. We get a lot of sensationalized news about new weight loss methods that will double your weight loss. And then when you look at the research paper, it says it did, in fact, double people’s weight loss, but it took them from losing a 1/3 of a pound to 2/3 of a pound in a month. That’s not quite the staggering claim that it seemed to be initially. So I think checking against the actual findings and checking against the methodologies of these studies is a really, really essential part of putting these in their right place.

SHOSHANNAH BUXBAUM: Yeah, I think that’s great advice, and hopefully our listeners will utilize that next time they see some wild headlines out there. So Aubrey, thank you so much for being on Science Friday. It’s been a real pleasure talking to you.

AUBREY GORDON: Likewise, what a joy.

SHOSHANNAH BUXBAUM: Aubrey Gordon is the co-host of the podcast Maintenance Phase and author of the book, You Just Need to Lose Weight and 19 Other Myths About Fat People. For Science Friday, I’m Shoshannah Buxbaum.

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