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TED Health

24 Sep 2026 · 12m · 7 chapters

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The Myth of Normal (1/5): The brain science of obesity | Mads Tang-Christensen

In short

“The Myth of Normal (1/5): The brain science of obesity” argues obesity is a complex, disease-like condition driven by genetics, environment, and brain-gut signaling—not just willpower or personal failure.

Guest

Mads Tang-Christensen, MD-PhD obesity researcher studying what people eat and how bodies respond; focuses on brain circuitry controlling eating behavior, especially GLP-1.

Key claims

Obesity meets common disease definitions (impairs function, increases susceptibility to other diseases, can be caused by genetic impairments). Human weight trajectories show “obesity-prone” vs “diet-resistant” patterns. Genes haven’t changed, but calorie-rich food availability has. The brain holds the key via gut hormones.

Notable examples

Barry Levin’s rat studies producing diet-resistant vs obesity-prone lines; GLP-1 effects on nerve cells controlling appetite; mention of leptin and POMC deficiencies.

Written by AI. May contain mistakes.

Chapters

1:33

Obesity as a Complex Disease

Mads Tang-Christensen discusses the complexities surrounding obesity.

“Say hi to new Kashi Gut Health Granola, a straightforward, delicious way to fuel your gut, made with prebiotics, fiber, and cultures.”
4:08

Obesity as a Complex Disease

Mads Tang-Christensen discusses the complexities surrounding obesity.

“Our next episode is all about a pandemic, not COVID-19, the global obesity pandemic that's been plaguing the world for 30 years.”
4:41

Understanding Weight Distribution

Insights into how genetics influence weight differences among siblings.

“Have you ever wondered why a pair of siblings living in the same house, with the same parents, with the same food, sometimes in opposite side of the weight spectrum.”
6:38

The Case for Obesity as a Disease

Arguments supporting the classification of obesity as a disease.

“If you take a thousand kids and weigh them, their weight will also be distributed in a bell-shaped curve, some skinny, some in the middle, and some heavy.”
10:05

The Role of GLP-1 in Obesity

Exploration of GLP-1's role in regulating food intake and weight.

“So obesity as a disease by this measure?”
12:00

Future Perspectives on Obesity Treatment

Discussing future directions in treating and understanding obesity.

“sitting in areas that control whether we eat or not.”
14:00

Introduction to Obesity Treatment Goals

Learn about the ambitious goals in obesity treatment and prevention.

“with a prevention, a treatment, or even a cure for people living with obesity like we strive for with any other chronic disease.”
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Transcript

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1:56TED Health: Try new Kashi Gut Health Granola.

2:02TED Health: Hey, it's Shoshana, and welcome to my September playlist. Fall has a way of resetting our routines, new schedules, new rhythms. And with that reset comes a good chance to revisit our assumptions, too. So I've been thinking about a question that comes up constantly in health and medicine, but we don't always stop to examine it. What do we mean when we call something normal? In science, we rely on norms all the time. Normal weight, normal vision, normal behavior, normal ways of coping, functioning, or moving through the world. Those categories can be incredibly useful, but they can also flatten a lot of human complexity.

2:41TED Health: because bodies and brains don't always fit neatly into the boxes that we've created for them. And sometimes what we think of as a personal failing, a limitation, or even a disorder looks very different once we understand the biology, the environment, or the assumptions underneath it. So I pulled five conversations from the TED Health Archive that make me rethink some of those assumptions. You'll hear from Mads Tang Christensen on why obesity is far more complicated than willpower. Kate Kale on why autism is so often missed in women and girls. Andrew Leland on why blindness is better understood as a spectrum than a binary.

3:21TED Health: Amy Baxter on the surprising ways our brains shape the experience of pain. And Casey Davis on why something as ordinary as doing the laundry can become incredibly difficult, and why that has nothing to do with your worth. These episodes cover very different territory, but they all share a common idea. The more closely we look at what we call normal, the more complicated and often more interesting the picture becomes. And I think there's something freeing in that. It invites us to be a little less certain about the judgments we make, and about other people and about ourselves. So this playlist is about rethinking normal.

3:59TED Health: Where our assumptions come from, who they leave out, and what we might see differently when we start questioning them. This is TED Health. I'm your host, Dr. Shoshana Ungerleiter. Our next episode is all about a pandemic, not COVID-19, the global obesity pandemic that's been plaguing the world for 30 years. In his September 2021 Ted Salon talk, obesity researcher Mads Tang Christensen dispels the myth that obesity is a lack of willpower and how our genes and environment play a role in excess weight. Listen in as he shares his perspective that obesity is a complex disease and why we should treat it like one if we want to find a cure.

4:41TED Health: Lundsen for all. Have you ever wondered why a pair of siblings living in the same house, with the same parents, with the same food, sometimes in opposite side of the weight spectrum. My name is Maz, and for the last 25 years, I've been studying what we eat, when we eat, and how much we eat. And probably more importantly, I've been studying how each our unique bodies respond differently to the same food and the same environment. To be more precise, I study obesity. During my training as an MD-PhD, I was very fascinated by serious experiments done by Barry Levin. He took 100 rats and subjected them to high-fat feeding.

5:29After months of feeding, he ended up with a bell-shaped curve and a weight distribution with some skinny rats and some obese rats and some in the middle. What he then did was to take the skinny rats and breed them among themselves and the heavy rats, and he bred those among themselves. And after rounds of breeding, he ended up with two distinct populations, a diet-resistant rat and a obesity-prone rat. And here's the really interesting part. Then he took the skinny or the obese and either massively over or underfed them. And their weight would, of course, go up and down depending on the dietary regimen.

6:12But it was as if their little bodies would remember the same old weight trajectory. So once the dietary regimen was stopped, the rats went right back to the initial weight trajectory. It was like as if you could dress up the obese rat in a skinny sheep's clothing, but the obese rat nature was still scratching to get out. The same thing applies to humans. If you take a thousand kids and weigh them, their weight will also be distributed in a bell-shaped curve, some skinny, some in the middle, and some heavy. We know that some of the skinny kids will remain skinny throughout life, and some of the obese kids will stay obese throughout life.

7:01You could argue that their weight, to some degree, has been predetermined. You could also argue that obesity is a disease. Wait, did I just say that? Obesity is a disease? Yes. There's actually data and science that shows that. And I've made it my audacious life goal to come up with a solution to prevent, treat, or even cure obesity. Let me explain. In the early 1980s and 1990s, obesity was considered a potential global problem. a global problem of a magnitude that led WHO in the end of 1990s to declare obesity a global pandemic. And I probably don't have to tell you why. Higher rates of diabetes, hypertension, cardiovascular disease, even some cancers, osteoarthritis, and a clear link to mental conditions such as depression.

7:58So as the number of obese individuals grew, so did the number of people suffering from these diseases. Today, more than 50 % of the U.S. adult population are living with obesity or overweight. From a health perspective, that is devastating. But it's not only a U.S. problem. The obesity surge has made obesity a global health problem. Many inside and outside the mental community believe obesity is not a disease. They believe that obesity is a condition. a condition brought about by too much eating and too little exercise. As a matter of fact, a lot of people living with obesity think that too. They believe that their weight is 100 % their own fault, which can lead to self-blame and low self-esteem, and perhaps even shame or stress eating, which is both heartbreaking as well as counterproductive.

9:01But where is the scientific proof that obesity is a disease? Well, medically speaking, there's many ways to define disease. But let me give you just three examples. As a process that impairs your functionality and reduces life expectancy. Obesity? Check. You can define disease as a process that leaves you more susceptible to other diseases or causes disease. Obesity? Check. Or you can define disease as a genetic impairment that leads to functional impairment, like, for instance, a duplication of genes on chromosomes. There are clear evidence that a single gene mutation can lead to obesity, such, for instance, lepsin deficiency and POMC deficiency.

9:51We also have two, three genes leading to obesity, and it's my prediction that we, by the year 2030, will be able to explain most obesity by the genetic makeup of the individual. So obesity as a disease by this measure? Check. Let me be clear. We humans have had the same genes for decades. And just recently, obesity has become a bigger problem. How do we then explain that? One obvious thing is actually food, especially calorie-rich food, which is much more readily available. It's relatively easy and also relatively cheap to eat your entire daily need of calories via fast food or big, soft drinks.

10:42So genes do play a role, but the environment also plays a huge role. The overabundance of calories in certain communities is a relatively new thing, and our genes haven't quite adapted yet. In the history of feast and famine, genetic selection has prepared us much better for famine, and for good reason. Starvation is bad, but you could also argue obesity is bad. And if obesity is a disease, how do we then prevent, treat, or even cure it? I believe that the brain holds the key. I have always been fascinated with how small electrical signals in discrete parts of the brain lead to big behavioral changes.

11:30And my study of the brain led me to glucagon-like peptide 1, or GLP-1 for short. GLP-1 is a hormone and a signal molecule that is produced both in the gut and in the brain. The brain speaks to the gut and the gut speaks to the brain. Yes, that's right. Your belly and your brain is literally connected. Our research led us to see that GLP-1 has an effect on nerve cells sitting in areas that control whether we eat or not. So, for instance, if we increase the level of GLP-1, the body's desire to eat or overeat food gets turned off. GLP-1 serves as the full signal in your car's gas tank. I've spent years and decades mapping the circuitry of GLP-1 and how GLP-1 interacts with other signal molecules and hormones.

12:28All of these things go together and control food intake, body weight, and the control of eating behavior. And what does that all mean? Well, today we have engineered and studied the molecule, so we now have a molecule that can lead to a significant weight loss. Obviously, GLP-1 is not the whole answer. We and others have discovered numerous of hormones and other signal molecules that are also pivotal for the regulation of food intake and body weight. And it may end up that these signal molecules and hormones are even more important than GLP-1.

13:11so there's plenty for us to do there's still plenty for us to explore so this is not the end it's not even the beginning to the end but perhaps this may be the end to the beginning we may have a massive weight crisis on the planet today but the good news is we are on the right paths. We now have solutions for people living with obesity, and the next steps will be to understand even better the problems people living with obesity are facing, to understand even better how genes and environment play together, and understand finally how all these things come together and determine our body weight. Then, and maybe just then, we will be able to come up with a prevention, a treatment, or even a cure for people living with obesity like we strive for with any other chronic disease.

14:10And this, this still remains our audacious life's goal. Thank you.

14:20TED Health: Today's episode is sponsored by Kashi. Say hi to new Kashi Gut Health Granola, a straightforward, delicious way to fuel your gut, made with prebiotics, fiber, and cultures. My favorite flavor, blueberry almond, has perfectly crispy clusters, delicious almonds, and bursts of whole blueberries. It's an easy fit for a daily routine, whether that's for breakfast or a snack. In a world of overwhelm, it's a straightforward, delicious choice. Try new Kashi Gut Health Granola.

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From the publisher

Your belly and your brain speak to each other, says obesity researcher Mads Tang-Christensen. Offering scientific proof that obesity is a disease influenced by genetics and the environment, he introduces a molecule discovered in both the brain and gut that helps control appetite -- and which could be engineered to promote healthy weight loss for those living with obesity.


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