The Weekly Vlog - Susan Peirce Thompson, PhD
March 22, 2023
Hey there, it's Susan Peirce Thompson, and welcome to the weekly vlog. I want to talk to you today about something called the "obesity paradox." There's a lot of literature about this in science, and first I want to start off by telling you the story of how I first encountered the obesity paradox.
I need to take you back about 10 years. I was teaching a course called The Psychology of Eating and Body Image at Monroe Community College. And I'd been teaching this course for years. And one semester in this course, I had a student named Anna. And Anna was noteworthy for several reasons. One, she always sat in the front row, front and center. Two, she was an older returning student. She was my age, in fact. And three, she was brilliant. She always had her hand up in class. She was always speaking up. She always did the reading. And finally, she was very, very large. I estimate that she weighed about 350 pounds, and the desk was way too small for her and cut into her stomach as she sat there in this kind of typical school desk.
And Anna was brilliant and amazing, and she introduced me to a bias that I didn't even know that I had, a stereotype, a prejudice that said that large women should be meek and try to be invisible. I didn't even know that I had this bias in my mind, but I was reflecting after class how confronting it was for me and jarring that she was so vocal and had her hand up all the time. And I thought to myself, why is that? If she looked different, if she were petite, if she were a fit, white male, if she just looked different, would I find it so jarring that she spoke up so much?
And I realized, no, I wouldn't find it jarring. I would just find it delightful and amazing. And what happened was I got over that bias, and I did find her delightful and amazing. And in that course, I assigned a research paper, and it only had to be seven to 10 pages. And people had to go pick a topic on the psychology of eating and study it and write up a well-documented research paper. Anna's paper was something like 20 or 25 pages, and with reams of citations. And her paper was on the obesity paradox. She was in her 30s, her kind of mid to late 30s, and she had no markers of ill health, as large as she was. She didn't have high cholesterol. She didn't have high blood pressure. She didn't have high triglycerides. She had no markers of ill health. And she wrote this paper introducing me to the obesity paradox.
And the obesity paradox says that obesity is not always bad for your health. That, in fact, sometimes extra weight can protect your health in certain ways for certain outcomes. Now, this was surprising to me because I know there's a very... I mean, much, much, much, much larger literature in the scientific world that shows that obesity is very bad for your health. And Anna's paper said, yeah, not always. Not always. And Anna herself, like I said, had no markers of ill health. So what happened then is really sad. What happened is that... Well, first what happened is not sad. Anna and I became friends. When the semester was over, I learned a little bit more about her. She would stop by my office sometimes and we would talk. And turns out she had twins and a singleton just like me, three kids, same age as my kids, and also twins and a singleton, three kids.
And we started getting together and hanging out. And our kids started having birthday parties together, and we started having play dates together. And I got to know her husband and I got to know her mom, and we spent a lot of time together. We became, I don't want to say best friends, but pretty close for a long time, a few years. She was the main person that I spent my socializing time with.
Anna did not show interest in the way I was eating. At that time, I was very, very Bright. I was not eating sugar. I was not eating flour. I was weighing and measuring my food. This was before Bright Line Eating® existed, and I was doing it in a 12-step program for food addiction.
She did one day come to that program. She came to a meeting, more, she said, for the spiritual benefits of working the 12 steps. And she got into a group with me to work the 12 steps together. And that's when the story takes a sad turn. She got a sponsor who ended up sending her back to day one for something that she shouldn't have. It was just stupid and misguided. And that kicked her out of the 12-step group. And Anna got pissed off and started eating again, sugar and flour and so forth. She found another 12-step program that would let her eat whatever she wanted. And within a year, she was dead of a heart attack. She never saw her 40th birthday, and she left behind her three beautiful kids. And it was a very rude introduction to the obesity paradox for me. And rest in peace, Anna. I love you. I feel you.
And so over the years, I have made it a point to really look into the obesity paradox. Is it always bad for your health to be living with obesity? What about the people like Anna who have no markers of ill health even though they have class three obesity? Well, interestingly, a longitudinal study showed that if you just track those people longer, 80% of them, within 10 years, will develop the markers of ill health. Presumably, if you keep going in time, the rest of them will. And it does look like the obesity paradox is a hoax. It's a myth. It's an artifact of a ream of scientific inaccuracies, biases that are baked into these research studies. And I've been looking into it. And there are three major biases that together create this so-called obesity paradox.
Now, let me just say that carrying extra weight is unhealthy, and the more we look at it, the more it looks like, yes, that's really just true. I know that we would like to say that it's not true. It would be very PC to say that it's not excess fat that is unhealthy, that it's just ill health that's unhealthy, and sometimes that goes along with excess fat and sometimes it doesn't. It would be a way to really force us all to confront and eliminate our biases around excess weight, which we should be confronting and eliminating anyway, for sure. Prejudice and discrimination are never, ever, ever, ever, ever, okay.
But it does really look like carrying excess weight is just unhealthy, period, full stop. And so let me just talk a little bit about that. First of all, one could ask, is it causal? Is it the excess fat per se that's causing ill health? And the answer seems to be yes. For one thing, just look at brute force weight loss from not particularly healthy methods like, oh, taking the stomach and just manipulating its size so that it's too small to eat much and letting people continue to eat terribly unhealthy foods. Just the shrinkage of the stomach and the resulting smaller consumption of food results in less weight, which results in the reversal of a lot of poor health outcomes. And then five years in, as people start to regain the weight, their ill health comes back.
You can have people lose weight by other unhealthy means like drinking these heavily processed 500-calorie shake concoctions where they're filled with sweeteners and colorings and chemicals, but people lose weight, and their health gets better. Just about any method you try to make people lose weight will result in better health. And then as soon as they start gaining back their weight, their health gets bad again.
So let's talk about the obesity paradox. There is this fairly sizable literature now showing an obesity paradox. And here's where it's coming from. First of all, if you look at health and, really, mortality outcomes, epidemiologically, so over large samples of people, you're just looking at their BMI and their likelihood of dying, what you find is that people at a normal BMI are not the least likely to die. It's actually people at an overweight BMI that are the least likely to die. And then it looks like people with class one obesity and a normal BMI are about equally likely to die. And then the only people with a really elevated likelihood of death are people who are underweight and people with class two, class three, class four, extreme obesity. And so it forms a U-shape curve with the lowest likelihood of death actually bottoming out at an overweight BMI.
So what's the deal with this? Well, this brings us to the first bias that's baked into a lot of these studies, which is the use of BMI as a measurement. And the use of BMI is flawed because it's not actually measuring fat, it's just measuring mass. And that will of course inflate the BMI of someone who's got good muscle tone. And if you look at fat instead of just mass, that U-shape essentially goes away. It becomes a line. It becomes basically a line. Now, it's true that it's not great for your health to be underweight. That is true. But once you get to a normal BMI, risk of death just goes up from there.
So there are people who have really good muscle mass, and they tend to test out as overweight or obese because they've got good... muscle weighs a lot, right? And then you've got all these people who are at a normal BMI. A lot of these folks in India, for example, the wealthier classes in India who aren't really allowed by their culture to lift a finger or move at all, they have very, very, very poor muscle tone and a lot of fat, and they're at a normal BMI, but they're very fat. They've got like 30% body fat, 40% body fat at a normal BMI. And so these folks are skewing the data too.
So if you're not using BMI, if you use body fatness as the measurement, there's no U-shaped curve. There's no obesity paradox. Every bit of excess fat that you carry brings increased risk of death.
So the second flaw that's baked into the obesity paradox is the reality that people lose weight, often, for unhealthy reasons like end-stage terminal cancer, end-stage terminal AIDS. And as people wither away and die, lose a lot of weight, if you catch them in that end-stage condition, they might have a normal BMI. They maybe used to be overweight or obese. Now they have a normal BMI and oh, look, they're dead in two years or a year. And those folks really skew the data. So if you don't remove people who have lost weight involuntarily because of illness, the data are all messed up. And so you have to remove those people with these epidemiological studies. You have to take them out of the database. And when you do that, again, what you see is that every bit of excess weight that you carry increases your risk of dying, right?
Now, finally, there are all these studies contributing to the so-called obesity paradox on specific disease outcomes, like how long are people likely to live after a stroke? What about renal cell carcinoma? What about these specific diseases? And a lot of these studies show that people who are carrying excess weight live longer. What gives? Well, now we're going to talk about something called collider stratification bias, which is a term you don't need to remember, but it's a bias. It's a bias that is known to reverse the direction of an effect like obesity causes death. But we can reverse that effect if we bake this bias into our study by not controlling for the right factors.
So it didn't take me long to find one of these studies. I just Googled a study, and sure enough, here comes up the Framingham study that you might have heard of this. This was a long, long, long-term longitudinal study of people in Framingham, nurses, I believe, who have been studied over decades. And they looked at likelihood, among other things... I mean, they've studied these people ad nauseum. It's an amazing longitudinal study on health. They looked at how long people were likely to live after a stroke.
Now this study, I just read it, and I was like, "Oh, look, it's got this bias baked in." And what they found was 10 years after a stroke, the people who were overweight before the stroke, not obese and not normal weight, overweight before the stroke, were likely to live the longest, longer than people who were at a normal BMI before the stroke. Now, they did use BMI as the measurement, so it's got that bias baked in. But here's what they didn't account for: smoking.
So the reality is that someone who's at a normal BMI who has a stroke is way more likely to be a smoker. Someone who's overweight and has a stroke may or may not be a smoker. They might have had the stroke because of their weight. And because you've got significantly fewer smokers as a little subgroup in the population of overweight people, that group is less likely to be dead within 10 years after the stroke than the normal weight people because so many of the normal weight people who had a stroke were heavy smokers. So that's how collider stratification bias is baked in. And these folks used BMI to study it all, and they didn't control for smoking. And they were like, "Oh, look, it looks like carrying some excess weight is protective." It's like, no, it's not. You actually have more smokers in that group. More non-smokers, actually, in that group, more smokers in the normal-weight group.
So these are the three biases that are baked into these studies. And when you control for all three, the obesity paradox is non-existent, nowhere to be found. It looks like every excess pound that we carry, on average is going to confer likelihood of death, worse health outcomes. The latest study that I've seen that controls for everything shows that carrying excess weight confers a 91% increased risk of death, 91%.
And then this Rand study that just came out where some economists and researchers at the Rand Corporation, they looked at smoking, heavy drinking, and poverty, and obesity, and they asked which of these is the worst when it comes to chronic disease and likelihood of death? And oh, it wasn't actually likelihood of death. It was chronic disease and expenditures due to ill health. It was an economic study, so money spent on ill health expenditures.
And obesity was the worst. Obesity was worse than smoking. It was worse than poverty. Poverty was second worse. Obesity, poverty, then smoking, and then heavy drinking. Those were the worst factors for chronic disease and money spent on ill health. So what about these people like Anna, while she was still alive, who don't have any markers of ill health? They might be living with class three obesity, extreme morbid obesity, but their triglycerides are fine. Their blood pressure is fine. Their cholesterol is fine. They may exercise. And they're like, "Look, I am not unhealthy. I'm fat, but I'm not unhealthy." What they have though, is they have genes that protect them from the ill health effects of excess weight, but the excess weight catches up with them eventually.
But they do have some protective factors. So we're studying more about the microbiology of how those genes protect them exactly and what that looks like. There are some protective effects that some people have genetically. But it doesn't last forever. The ill health catches up with them eventually.
So why is this important to understand that there is no obesity paradox? I think one is because our society seems to be really wanting to put its head in the sand like an ostrich and just not face the fact that it's not good that the obesity pandemic keeps rushing ahead, that weight keeps climbing and climbing and climbing, that obesity is spreading around the world, that we now have more people suffering with overweight and obesity everywhere in the world, including in the poorest countries in the world than we have suffering from malnutrition, that there are countries in Europe that are starting to catch up with the United States in terms of obesity. It's hard to face. And it's easier to say, "Well, this isn't necessarily a bad thing."
It's also important because we need to hold the nuance of all of this, right? This reality that it is important for all of us to confront our own biases. And Anna, I love you for many reasons, and partially for helping me to see my prejudice when I didn't see it, that I am so glad that you were as full of life and as bold and audacious and came to class with a sundress on and flowers in your hair and raising your hand at every opportunity. It was so beautiful to see you live full-on like you did. And we all need to look at that, right? What are we expecting of people who are living with clinical obesity? Are we expecting them to be fat and lazy and stupid? I mean, literally, yes, fat, but are we expecting them to be stupid and lazy, as research shows that over 90% of doctors and nurses are? They believe that people living with obesity are stupid and lazy.
We need to confront that. And we need to simultaneously never, ever give up on helping people to lose weight because it is still in everyone's best interest to get their weight within a healthy range, if you care about health, right? Now, that's, I guess, an assumption. If you care about health, that is kind of job number one. It is the number one thing even ahead of quitting smoking. Get your weight into a healthy range. And I think it's important that we face that.
But you will confront and see, you will notice people talking about an obesity paradox and that it's not necessarily unhealthy to be overweight. And I just want you to be armed with the facts. So them's the facts.
And that's the weekly vlog. I'll see you next week.