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- [00:03]
A
Welcome to the first of our special series focused on obesity in 2026. I'm your host, Dr. Neal Skolnick, professor of Family and Community Medicine at the Sidney Kimmel Medical College of Thomas Jefferson University. This special edition of Diabetes Core Update is sponsored by Lilly. Over the last five years, obesity has changed from a risk factor that we talk about with patients to a critical disease that we treat. Treatment with GLP1 receptor agonists, most commonly semaglutide, and the dual GLP1 GIP agonist, tirzepatide, has changed the landscape of weight management and with it, the landscape of primary care. These medications have changed obesity from the category of a risk factor that frankly we didn't address often enough or strongly enough to the category of a chronic disease now that we treat on a routine basis. These medicines have enabled clinicians like ourselves to effectively treat obesity in a manner that leads to improved health outcomes, not just weight loss. And those health outcomes are are measured by things like improvement in blood pressure, cholesterol, triglycerides, blood sugar, decreased insulin resistance, as well as in improvements in obesity related diseases like diabetes, obstructive sleep apnea, metabolic associated steatotic liver disease, and even atherosclerotic cardiovascular disease. Nonetheless, it takes a while for our understanding of obesity as a chronic disease to make its way into practice. There's still a lot of misunderstanding out there both about the causes of obesity as well as the underlying pathophysiology that makes it so incredibly difficult for patients to lose weight once they've sustained an increase in their weight and then even more difficult to sustain the weight loss. It's if they're able to lose that weight in the first place. Today we're going to talk about understanding obesity as a chronic disease and how that understanding directly affects the way we practice medicine in the office and the way we treat patients. Joining us today to discuss this critically important topic are two master clinicians. The first is Donna Ryan. Dr. Ryan is a Professor Emeritus at the Pennington Biomedical Research center in Baton Rouge, Louisiana. She is the past president of both the Obesity Society and the World Obesity Federation. Dr. Ryan's research includes being an investigator in many of the trials that we're all familiar with, from the Diabetes Prevention Program trial published in the New England journal back in 2002, to the Vash dietary studies, to the Look Ahead study, to even the select study just a few years ago that showed the effect of GLP1s on cardiac endpoints, and then this past year, the Maritime study of a once monthly GLP1 receptor agonist, GIP antagonist and most recently Donna, unless I miss something in the last three weeks, the attained to trial of orthodol. Donna, welcome to our podcast.
- [03:39]
B
Thank you for having me. I'm delighted to be here.
- [03:42]
A
Also Joining us is Dr. Susan Kucera. Dr. Kucera is the program director of the Jefferson Health Abington Family Medicine Residency Program and an associate clinical professor of Family and Community medicine in the Sidney Kimmel Medical College of Thomas Jefferson University. Sue, welcome back to our podcast.
- [04:04]
C
So happy to be here. Neil, thanks for having me.
- [04:06]
A
Donna, before we dive into our main topic, can I ask you what led to your interest in obesity? Long before obesity was the hot topic it is today.
- [04:19]
B
Look, I give full credit to George Bray. So I was working at the Health Science center in New Orleans for LSU and they asked me to go to Baton Rouge to help start the Pinnington center. Wealthy philampines philanthropist CB Doc Pennington had given the university $125 million to build a nutrition research institute. And the first director was George Bray. George is the father of obesity research and he and his the subsequent director Claude Bouchard and all of the fantastic scientists that they recruited had an enormous influence on me. And I changed careers midstream and went from oncology to obesity, nutrition, diabetes. Really a total total about face. And you know, it was just such an interesting and exciting time. Although a lot of the work was futile, you know, we, we, we looked at a lot of medicines that didn't work out. We did a lot of lifestyle interventions that unfortunately the weight was not sustained in that we could achieve weight loss but it would not be sustained. So it has really been an incredible adventure and I owe it all to Pennington, George Bray and Claude Bouchard.
- [05:44]
A
Isn't that something? And Don, we'll talk in a few minutes about that change and what were some of the things that allowed the leaps in thinking that went from things being not incredibly effective to the efficacy we have today? You know, when we look at over that period of time, it's also incredible how much of an increase there's been in obesity. So if we go back to 1975 and I just checked this on the CDC charts, there was kind of an inflection point. Obesity had been increasing and then it really started increasing rapidly. So in 75, about 15% of US adults were obese. Twenty years later, by 2005 that rate had reached 35%. And today about 40% of US adults are obese, another 30% are overweight. And I know there's a lot of complexity in describing why that might have occurred. But can you go over briefly some of the theories about why obesity has increased? Clearly, our genetics didn't suddenly change. Something happened. Donna?
- [06:56]
B
Yeah. What about that obesogenic environment? You know, that's how we think about it. So, you know, the genes have not changed. What's changed is the environment. And it's caused the expression of those of us who have genetic risk factors for excess, abnormal body fat accumulation. And so, you know, there are two sides of the energy balance equation. Right. And look at all the enormous changes in the amount of physical activity that's required for both work and way that's occurred in the last 50 years, you know, during that period of inflection, you know, but the dietary, the food environment gets a lot of, lot of credit for the obesity epidemic. And, you know, some epidemiologists really point to the. In the United States, the bills that were introduced in the Department of agriculture in the 70s and 80s that really promoted price supports for corn, which then became feed for cattle, and the production of high fructose corn syrup, all of these things really enabled us to have very inexpensive fast food. Yeah. If you look today, 60% of the average American diet is fast food. It's ultra processed foods. So, you know, I think the. There are many, many contributors to the obesity epidemic. But I think that the two. Two big changes in the food environment and the physical activity environment really deserve the credit or the blame, depending on how you're. How you look at it. You know, the. I think the. The food environment is such that it's really amazing. They've given us exactly what we wanted. Right. They've given us delicious, readily available, inexpensive food all the time. Yeah. And so that's a big driver of weight gain. The other thing that's a big contributor to the obesity epidemic is the understanding that once you gain weight, it is very difficult to lose it and keep it off.
- [09:16]
A
Yeah. You know, Donna, thank you for distinguishing between the two, because I've seen a lot of people confused by that idea of obesity is a chronic disease, meaning there's nothing we can do to prevent it. Well, there's a lot we can do to prevent it. That obesogenic environment, a toxic food environment with ultra processed foods, something that finally the dietary guidelines have really emphasize that we need to get away from is critically important because there's a lot we can do with primary prevention. And that's very different than treating a disease, obesity, once it's developed.
- [09:57]
B
But you know, Neil, we've been very successful in the United States in exporting our lifestyle around the world. And we are really responsible for a lot of the global obesity epidemic because the American lifestyle is something that is being adapted globally.
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A
Yeah, we've seen those rates of obesity increase in other countries, and it's pretty sad and scary. I want to shift gears now, Donna, to talking about obesity once it is established. So obesity is a chronic disease. Can you share with us the evolution of scientific thinking over the last 30 years as we've come to understand obesity better as a chronic disease?
- [10:44]
B
Yeah, you know, I'm so glad you, you frame that question sort of as a timeline because it's so important to understand that we did not always have this knowledge. And, you know, it really begins in, in the 90s, in 1995. There's a wonderful paper by Jules Hirsch, Rudy Leibel and Mike Rosenbaum. And what they did is they increased people's weight by giving them extra calories, sort of feeding them and making them gain extra weight and then having them lose weight. And they, they correlated this with your metabolic rate. And what they demonstrated was that when you reduce your weight by 10%, your metabolic rate decreases by more than 10%. They demonstrated what is called metabolic adaptation. And so that's really all. That idea has only been around since the 1990s. The other sort of big I think, thing that's influenced this idea is a paper that was published by Priya Sumithran and that was published in just 2011. And what she did is she took individuals and she reduced them by 14% and then looked at all the appetite hormones and measured they're hungry, hunger and satiety and food intake. And what she demonstrated is that when you're reduced, you are hungrier, you are more susceptible to reward eating. And this persists. It persists for up to a year after, after you've reduced weight, even though you've gained some weight back. So this idea that the body's in this reduced state has effects on both hunger and satiety. It makes you want to eat more and also on your energy expenditure. It makes you more efficient. It makes your. You have a lower resting metabolic rate. These ideas about the defense of your body weight and the drive for the body to get back to where it was before you lost weight, those are really transformative in our understanding of why obesity is a chronic disease. It's not just nothing to do with the obesogenic environment. It has to do with your biology.
- [13:03]
A
And that's so important. You know, it's interesting when I'VE talked to patients in the office, and I explained to them a bit about that pathophysiology that so often is one of those pull out the tissue moments as they learn that it's not their fault. And I've actually, many patients have said that those specific words. So you mean it's not my fault. And unfortunately, people so often feel that it's a lack of willpower, which it is not. Sue, have you had similar experiences in the office?
- [13:43]
C
Oh, for sure. And I, you know, I really think about, like, the shift that's happening in thinking about obesity as a chronic disease. And the truth is, I think the patients have really embraced this, and they might have even embraced it a little faster than we have. As clinicians, I think we know, like, deep down we understand all of these things, but as it's trickled down to patients, and a lot of this has to do with new treatments and medications, they're now coming in, understanding this a little bit more and having a lot more acceptance of where they're at. So it's been really an interesting transition in my world of patients coming in, wanting to talk about this and being very open to the conversations because of all the conversations that are happening outside of the doctor's office.
- [14:27]
A
So, sue, you said that patients seem to be learning about obesity as a chronic disease. And that's really important because it becomes critically important that we as clinicians support patients understanding and that we convey that understanding for people who don't really know or don't fully embrace it and support it for those who do. But interestingly, there was a survey a couple of years ago of doctors that showed that over half of doctors still do not consider obesity a chronic disease. Rather, they feel it's a lifestyle issue. And over 40% said they thought that people could lose weight if they just tried hard enough. And we think of ourselves as people of science. And because of that, I suspect I've heard a number of clinicians say to me something like, let's be honest, if you cut back on calories and exercise more, you'll lose weight. Because it's physics. It's calories in, calories out, and the weight has to come down if there's more calories burned than calories consumed. And it's always impressed me that when they say this, they're really not understanding the science of obesity. And the things that underlie obesity is, as Donna talked about, all the hormonal shifts that affect appetite regulation and the metabolic adaptation that occurs when you lose weight. All the things Donna Just went over my question for you is how do you address those sort of statements that really affect people's attitudes when you hear that and how do you talk to you teach. A lot of residents and students, some of whom I know, have said that.
- [16:16]
C
Yeah, you know, this is a, it's a really interesting idea to, to consider. So calories matter, your food quality matters, those things all matter. But it's not a simple equation. Right. If somebody has a fever, we're just not going to say, well, they, they've created more heat than they've dissipated. We're going to say, well, well, why do they have a fever? Right. Like what's driving this? And you know, Donna addresses really well, there are so many complex factors about why people eat more, why they metabolize differently, that has really driven this concept of obesity as a chronic disease. Right. So there's a why behind here that we need to understand and embrace. And without that accurate understanding, we're really unable to provide non judgmental care to our patients. Right. And there's no other chronic disease that we discount all of the genetic factors that determine how their disease progresses. So, you know, there is, there is an important lifestyle component to this, like any chronic disease. But I think the truth is, you know, to be non judgmental physicians, we have to embrace this and move forward with it.
- [17:30]
B
I love that Hot Sue. It's that it's so true. And you know, I think what it does is it legitimizes medications for obesity. In other words, you must fight biology with biology. And I want to say all of those lifestyle interventions I did, we were doing things that were trying to promote your biology. We were slowing the rate of food intake, trying to allow your body's hormones to have their effect. You know, we were doing self monitoring because, you know, if you have, if you're more involved in the procurement and preparation of food, well, you will eat less. You know, we had some understanding of the biology and we were trying to do our best with the behavior.
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A
You know, it's interesting and at the same time, we need to also remember the importance of those behavioral interventions. When we look at exercise separate from its effect on weight, it has very important health outcomes that range from an effect on depression. There was a wonderful Cochrane review on exercise and depression the beginning of last month to an effect on decreasing cardiovascular illness separate from its effect on weight. So that holistic approach to patients remains important. I want to shift for a moment to the Lancet Commission's recommendations and Donna, that received a lot of press last year if you can review for us what the Lancer Commission has said about the refinement of the definition of obesity.
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B
Yeah, it really did. It got an enormous amount of attention and it got everybody talking, and that is a very good thing. So I think what the Atlantic Commission addressed is that the way we've been defining obesity is by bmi, body mass index. So body mass index is one number that's a function of your height and your weight. So it's really a measure of body size. It doesn't really say anything about body health, even about how much fat you have or where it is. So we know in terms of how obesity drives disease, is excess abnormal body fat contributes to the progression of a whole number of cardiometabolic parameters, and then just the burden of body fat itself can also produce disease. So what the Lancet Commission advised us to do was first, make sure that your patient does indeed have excess abnormal body fat. Don't rely on BMI alone, because some people can have a BMI of 30, 32, and they don't have excess body fat. They're bodybuilders, for example. And so what they want us to do is look at, not just body weight, bmi, they want us to also look at body fat. And so they gave us permission to measure body fat with. With a. And there's several things that are out there that allow us to do that, from DEXA to impedance through 3D optical digital anthropometry. You know, so we have different tools to measure percent body fat. We also. They also really promoted looking at where body fat was located through the use of waist circumference and waist to height ratio.
- [20:57]
A
Donna, let me ask you to pause there for a moment because I'm interested in Sue's thoughts on this issue about integrating body fat distribution in a primary care. Something that the idea has been around there for a long time but really hasn't happened. And this is an important issue because the reality is that bodybuilders, for instance, are often mentioned as individuals with high BMIs to lower body fat content. But very few of our patients are bodybuilders, and we recognize them when we see them. We don't need formal body analysis. It turns out that BMI is a pretty specific measure for elevated body fat, better than 90 to 95% specific, but it isn't a very sensitive measure. We're missing people with obesity who are overweight. And actually, when you use sensitive measures, it turns out that we're missing about a third to a half of people with BMIs of 25 to 30 when we just use BMI criteria. And those people are actually obese on more accurate criteria. So using a waist circumference of greater than 40 inches for men or greater than 35 for women clearly helps us identify many people with obesity who would not otherwise be classified as such. It also turns out, and I don't think this is as well appreciated, the waist to height ratio of greater than 0.5 is an even more sensitive measure. Obviously, that adjusts for people's height. In addition, those measures give us some insight into visceral fat, which is the fat distribution that most closely tracks metabolic abnormalities. So we have all this background and we're still not doing it. Sue, what are your thoughts about using measures like waist circumference or other accurate measures of obesity in primary care?
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C
Well, honestly, this is a really interesting concept. I think we all have patients in our clinical practice that we've seen with a complication of obesity like metabolic associated steatohepatitis or something of the like, who are in that overweight category, right? So I think intuitively we hear this and we, it makes sense to hear it. I think visceral fat is actually a very important concept. And I think that this measurement is something that we can really explain easily to patients. I think there's a lot of patient education about it, about why visceral fat matters, and maybe this is something in patient education that might help our case and help us discuss it with them. And I also wonder, would a shift away from BMI be a good thing in the concept of obesity as a chronic disease? Do we need another tool, another number, another discussion to have? And you know, based on what you just said, this might be something that is a good piece of data to discuss with patients. But the practicality of getting this, it seems easy enough, but I think it's probably more challenging than we think, getting our hands around a patient to measure their waist. Is it just another measurement that might be challenging for patients to go through, for us to measure and collect? So, again, implementing it might be harder than it seems, but I think the concept of it is something we really should start to think about and consider.
- [24:27]
B
So, you know, the, the promotion of identifying obesity was the very first thing that that Lansing Commission brought forward. And then they wanted us to make a second step and they wanted us to decide whether the patients had clinical obesity, in other words, had. Had illness associated with that obesity, or had what's called preclinical obesity. So this is, this is probably the most controversial Part of it. But in general, the concept is very good because there are some people who do have excess body fat was located in the, you know, it's. It's located predominantly subcutaneously and not a lot of cardiometabolic disease, even risk associated with it. But there are people who, who. Who don't even have a very large body size, but do have excess abnormal body fat and have complications. They have cardiometabolic risk factors. They can have diabetes, cardiovascular disease. And so the Lance Commission really brought those things forward and got those concepts on the discussion board for all of us.
- [25:36]
A
And I know there's been a lot of controversy over that. And as you said, particularly that idea of distinguishing preclinical versus clinical obesity. I'm curious, Donna, your. Your personal thoughts about that?
- [25:49]
B
You know, I think that the overall, overall idea, I endorse the methodology that they used. They gave you a list of 18 diseases, but it didn't make a lot of sense to me why just those 18 and diabetes was excluded. This is the disorder that is most closely linked to excess abnormal body fat. And difficult to understand why that was not on the list. But anyway, I think what needs to happen is there needs to be, and it's already occurring, Neal. There are studies underway that look at different techniques for identifying that clinical obesity, not necessarily the ones that are defined in the Lancet Commission, but sort of improvements on that. And I'm very hopeful that that is going to come up with some actionable items for people in the clinic, because really, that's what it's all about. I mean, sue, when you're in the clinic, you want to know, well, what sort of tool should I be using to diagnose and what sort of tool should I be using to determine if patients that I need to focus on with more urgency and with more intensity.
- [27:01]
A
Sue, did you have any thoughts on the commission's recommendations?
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C
Yeah, Donna, I think you hit the nail on the head there. You know, for me, this was a really nice way to formalize what we've all seen in our exam room for years, right? So that obesity is both independently associated as a chronic disease, but also a predisposing factor. And, you know, is it clinical obesity or preclinical? Again, all of this sort of spectrum of disease that we see, right? We see it every day. And I think two things. Formalizing it as a chronic disease gives us a framework that we're really used to using in primary care. Right. We kind of understand how to work in that framework, but also sort of that Separation of preclinical versus clinical obesity is again, the intensity of intervention can be gauged on that. Right. If someone comes in with a blood pressure of 220 over a hundred, I'm feeling very differently about that than if they're 130 over 80 or 140 over 80. And I, I think again, what the, these recommendations do is, is put all of this into a framework that makes a lot of sense for how we treat other chronic diseases.
- [28:08]
B
Very well. Stand.
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A
Yeah, no, that, that, that's critically important.
- [28:14]
B
Yeah.
- [28:14]
A
I want to sue, I want to throw a question out at you because the, the issue of obesity is a chronic disease is important. Donna went over the underlying pathophysiology and rationale for that being true. Yet that idea has received a lot of pushback from people. And, and I've heard people say, well, that removes personal responsibility from patients that they, if it's a chronic disease, then where's the responsibility come. I'm, I'm curious your thoughts about that.
- [28:47]
C
Yeah, I, you know, that never really held a lot of weight for me. Right. And then I think the reason being is every chronic disease that we treat has a lifestyle, personal responsibility component to it. Right. So you know, if you have blood pressure and you're not watching your, you know, your salt, your fruits, your vegetables, your exercise, diabetes, you know, if you got depression, right. There are all of these lifestyle pieces to every chronic disease. And so whatever people say about personal responsibility, that that's just, you know, what does the patient take on in terms of their lifestyle changes that they're going to do to help manage their chronic disease. Right. And so, you know, that was a, that's a really challenging thing to say to someone that this, it's a personal responsibility for this problem, but not for the other problems. And so I think we just have to be really careful to not, not use that language because it just puts stigma around something that we ask all of our patients to do no matter what chronic disease we're helping them manage in their day to day life. So yeah, you know, I, I think that anyone who is pushing on that, I don't think you'll find a lot of primary care doctors who will because we do this every day with every other chronic disease.
- [30:00]
A
And, and I like Donna, what you said, you need to treat biology with biology. You know, the, the obesity piece requires medicines, chronic disease. And it's not an either or, it's an and so much of life is, and, and we can also achieve optimal health if we also eat those fruits and vegetables, if we also exercise to the degree that we are able to. And, and that's how we achieve optimal outcomes. But the weight piece itself has to be treated based on the underlying physiology. We're almost out of time. Sue, do you have any final thoughts for our listeners?
- [30:44]
C
I mean, I'm so excited that, that this is being revisited in podcast form again, because really, in our, in primary care, our conversations with our patients over time, right, they're really at the forefront of what they, what we do. And if you can take the model of obesity as a chronic disease, that will help everybody, including our patients, have a framework of how we best take care of patients with clinical obesity. This is such a good thing for primary care clinicians, for the patients that they care for. Again, structure this in a framework that we can know how to work with. And I think everybody, at the end of the day, having their goals to work towards.
- [31:22]
A
Excellent. Donna, any final thoughts that you'd like to share?
- [31:26]
B
Yeah. What I'd like people to recognize is that, yes, these medications, they're wonderful because they do produce robust weight loss. We're all excited about that. But look, they have other qualities, too, that are equally amazing. These medications, these GLP1 receptor agonists, look, they have independent effects on glycemia. They reduce inflammation. We're seeing effects beyond weight loss. These are serious medications. We need to take them seriously. They're really going to have some incredible health impacts, I believe.
- [31:59]
A
It's so important. Dr. Donna Ryan, thank you so much for joining us.
- [32:04]
B
Dr. Neal Skolnick, thank you for having me.
- [32:07]
A
And Dr. Sutra Chair, thanks so much for joining us.
- [32:11]
C
Of course, my pleasure.
- [32:12]
A
And of course, most of all, thanks to our listeners. Thank you for joining us on this first part of our series on obesity, sponsored by Lilly. We've covered a lot. We've covered the change in thinking of obesity over time. We've discussed some of the root causes of obesity being in the obesogenic environment that we all live in and need to fight against. We've also talked about the difference between the development of obesity and then obesity as a chronic disease, where the pathophysiology is there, and there's things like metabolic adaptation that occurs when you try to lose weight. There's hormonal shifts that occur that make appetite incredibly difficult to combat. And we've talked about some biases that exist in the office and why, as Dr. Kucera said, this is like every other chronic disease out there, that there's a lifestyle component, but we need to treat the disease as a disease. As Dr. Ryan said, treating biology with biology. For the American diabetes association, I'm Dr. Neal Skolnick. Till next time, stay safe and keep learning.