Laura: Okay, Sophia, here's a wild statistic for you. Last year, 108 million people in the United States went on a diet. One hundred and eight million. Sophia: That's... a third of the country. So, we should all be getting thinner, right? The national waistline must be shrinking. Laura: Exactly. Except we're not. We're getting heavier. And that's the billion-dollar paradox we're unraveling today. Sophia: It’s a paradox that feels incredibly personal for so many people. The constant cycle of hope, effort, and then disappointment. Laura: And the book we're diving into today offers a stunning explanation for why that cycle exists. It’s Why Diets Make Us Fat by Sandra Aamodt. And what makes this book so compelling is that Aamodt isn't a nutritionist or a fitness guru. She's a neuroscientist, the former editor-in-chief of a top brain science journal, Nature Neuroscience. Sophia: So she's coming at this from a completely different angle—not about the food on our plate, but about the wiring in our brain. Laura: Precisely. She spent years of her career reading and editing thousands of neuroscience papers. This book is her answer to a question that haunted her personally after decades of her own yo-yo dieting: why is this so hard? Her viral TED talk on this has millions of views, so she clearly struck a nerve. Sophia: I can see why. It’s a question almost everyone asks themselves. So, where does she begin to untangle this mess? Laura: She starts with a concept that completely reframes the problem, something she calls the diet roller coaster. It’s the perfect metaphor for the experience so many of us know all too well.

Sophia: The diet roller coaster. I think I’ve had a season pass for most of my adult life. What’s her take on it? Laura: She tells this incredibly vivid story about a man named Dennis Asbury. In the mid-90s, Dennis was 45 years old, weighed 283 pounds, and was deeply unhappy about it. His doctor prescribed him the infamous diet drug combo, fen-phen. Sophia: Oh, I remember fen-phen. That was the "miracle drug" that turned out to have some pretty serious side effects, right? Laura: Exactly. But for Dennis, at first, it felt like a miracle. His appetite vanished. He became obsessive, meticulously tracking every single calorie and every minute of exercise. He gave up all his favorite foods. He would wake up at 3 a.m. just to walk on his treadmill. He got his daily intake down to as low as 600 calories. Sophia: Wait, 600 calories? That's less than what a toddler eats. How is that even physically sustainable? That sounds like a full-time job in deprivation. Laura: It was. And it worked, in the short term. He lost an astonishing 123 pounds in six months. He was thrilled. But this is where the book’s central argument comes into play. Aamodt explains that Dennis wasn't just fighting his habits; he was fighting his own brain. He was fighting a biological system called the "defended weight range." Sophia: Defended weight range? What does that even mean? Is my brain secretly a bodyguard for my body fat? Laura: In a way, yes! Aamodt explains that a part of your brain called the hypothalamus acts like a weight thermostat. It has a preferred weight range for you, about 10 to 15 pounds, that it considers "normal." This is your defended range. If your weight drops below the bottom of that range, the brain panics. Sophia: So it's like my house thermostat? If I open a window in the winter to cool the room down, the furnace just kicks on and burns twice as hard to fight me and get the temperature back up. Laura: That is the perfect analogy. Your brain does the exact same thing. When you diet and lose weight, your brain declares a state of emergency. It thinks a famine has hit. So it turns up the hunger signals, making you feel ravenous. And, to conserve energy, it slams the brakes on your metabolism. You burn fewer calories just sitting, standing, even sleeping. Sophia: That is so frustrating. It explains why after a week of "being good," a slice of pizza starts to look like the most beautiful thing you've ever seen. Your brain is essentially screaming at you to eat it. Laura: It's screaming. And it’s also making that pizza taste better. The brain’s reward system gets dialed up, so high-calorie foods become almost irresistible. You’re fighting a three-front war: increased hunger, a slower metabolism, and a brain that’s making junk food seem like a divine reward. Willpower doesn't stand a chance. Sophia: But what about the people who do lose weight and keep it off? We all know someone, or at least we've heard of them. They're like unicorns. Laura: They are like unicorns. And the data Aamodt presents is just staggering. Most studies show the vast majority of dieters regain all the weight they lost within a few years. But here’s the real kicker: on average, people who go on a diet end up heavier five years later than people of the same initial weight who didn't diet at all. Sophia: Hold on. You’re saying the very act of dieting could be making people fatter in the long run? Laura: That’s exactly what the science suggests. The diet itself, the act of restriction, triggers a biological overcorrection. Your brain fights so hard to get you back to your defended range that it often overshoots, and then defends that new, higher weight. Each failed diet can potentially nudge your brain's thermostat a little higher. Sophia: That is a devastating thought. The very tool we're told to use to solve the problem is actually the mechanism that makes it worse. It’s like trying to put out a fire with gasoline. Laura: And that's why she calls it a roller coaster. You get the thrill of the drop—the initial weight loss—but the climb back up is inevitable, and it might leave you higher than where you started. Dennis Asbury’s story didn’t end with that 123-pound loss. The moment he went off the drugs, the battle began. Sophia: Okay, so if my brain is fighting back that hard, what does that fight actually look like from the inside? What happens in our bodies and minds when we cut calories so drastically? Laura: This is where the book gets really fascinating, and a little terrifying. It dives into the science of the starvation response.

Laura: To understand what dieting does to the brain, Aamodt takes us back to 1945, to one of the most famous and ethically questionable studies ever conducted: the Minnesota Starvation Experiment. Sophia: That sounds ominous. What were they trying to find out? Laura: It was the end of World War II, and researchers wanted to know the best way to re-feed the millions of starving people across Europe. So, they recruited 36 healthy, psychologically stable young men—conscientious objectors who volunteered—and they decided to starve them. For science. Sophia: Oh boy. How did they do it? Laura: For six months, they cut their daily calories in half, to about 1,570, while making them walk 22 miles a week. The physical effects were predictable: they got weak, they were constantly cold, their strength plummeted. But the psychological effects were the real story. These well-adjusted young men became completely obsessed with food. Sophia: Obsessed how? Laura: They would read cookbooks and recipes for hours. They’d hoard them. They would spend what little money they had on food they weren't allowed to eat, just to look at it. They became irritable, withdrawn, and anxious. Fights would break out over tiny scraps of food. One volunteer became so psychologically distressed, suffering from dreams of cannibalism, that he had to be removed from the study. Another, in a moment of sheer desperation, took an axe and cut off three of his own fingers. Sophia: He did what? That's terrifying. It sounds less like a scientific study and more like a horror movie. The psychological toll is just unimaginable. Laura: It was profound. And it reveals what happens when the brain enters starvation mode. But the most important part of the experiment was what happened after the starvation period ended. When the men were allowed to eat freely again, they couldn't control themselves. They would eat massive amounts, over 5,000 calories a day. They suffered from binge eating, depression, and mood swings for months, even years. And here’s the key finding: on average, they gained back all their lost weight, plus about 10% more. Their bodies overcorrected. Sophia: So the experiment designed to figure out how to cure starvation ended up creating the very conditions for long-term weight gain. Laura: Precisely. And Aamodt uses this to make a powerful point. She says your brain doesn't know you're on the keto diet for a wedding. It just knows calories have been drastically cut, and it assumes there's a famine. It activates what she calls your 'inner rat'—that primal, rodent part of your brain that's designed for one thing: survival. Sophia: The inner rat. I like that. It’s that frantic, desperate feeling. So that late-night pizza binge after a week of salads isn't a failure of my willpower, it's my inner rat staging a coup to save me from a perceived famine. Laura: That's the argument. The brain triggers these ancient survival circuits that make you hyper-aware of food, especially high-calorie food. It impairs your ability to recognize hunger and fullness cues. It makes you vulnerable to emotional eating and food marketing. The book quotes Dennis Asbury again, describing his post-diet mindset: "One Snickers bar, and I might as well just weigh three hundred pounds. My mind tends to that black-and-white thinking: either I’m good or I’m not." Sophia: That all-or-nothing thinking is the hallmark of every diet I've ever been on. The "what the hell" effect. You eat one cookie, feel like you've failed, and then eat the whole sleeve. Laura: And Aamodt’s response to him is simple: "It’s your inner rat." It’s not a moral failing; it’s a biological response. The book even cites studies on Finnish athletes in weight-conscious sports like boxing. Years after their careers ended, they were three times more likely to be obese than athletes from sports that didn't require constant dieting. Their repeated weight cycling had permanently altered their biology. Sophia: This is all pretty bleak. It feels like we're set up to fail. If dieting is a trap and our brains are actively working against us, what's the alternative? Do we just give up and accept whatever weight our body lands on? Laura: That's the million-dollar question, and it's where the book pivots from the problem to the solution. It’s not about giving up; it’s about changing the goal entirely.

Sophia: Okay, I’m ready for some hope. If fighting our bodies is the wrong approach, what’s the right one? Laura: The book’s answer is simple but radical in our culture: shift the focus from weight to health. Stop trying to be thin, and start trying to be healthy. The two are not the same thing. Sophia: I think we're conditioned to believe they are. That thin equals healthy and overweight equals unhealthy. Full stop. Laura: And Aamodt argues that this is one of the most harmful myths out there. She presents a powerful study on a program called Health at Every Size, or HAES. Researchers took a group of overweight women and split them in two. One group went on a traditional, restrictive weight-loss diet. The other group joined the HAES program. Sophia: What did the HAES program involve? No calorie counting, I assume. Laura: None. It focused on three things: body acceptance, eating in response to internal hunger and fullness cues—what's called intuitive or mindful eating—and finding enjoyable ways to move your body. The goal was to improve health behaviors, with zero emphasis on weight loss. Sophia: A diet program with no dieting. I love it. What happened? Laura: At the end of the first year, the diet group had lost some weight and their health markers, like cholesterol and blood pressure, had improved. The HAES group lost no weight, but their health markers improved just as much, and in some cases, even more. But the real story is what happened in year two. Sophia: Let me guess. The diet roller coaster came back around. Laura: You got it. By the end of year two, the diet group had regained all the weight they’d lost, and all of their health improvements had vanished. The HAES group, however, maintained their health improvements. Their cholesterol was still lower, their blood pressure was still better, and their rates of disordered eating had plummeted. They had built sustainable habits. Sophia: That’s incredible. It proves the point that the health benefits people see on diets often come from the behaviors—eating more vegetables, exercising—not from the weight loss itself, which is usually temporary. Laura: Exactly. And that’s the core of the book's solution. Aamodt shares her own personal experiment. After decades of dieting, she made a resolution: for one year, she would not diet, she would not weigh herself, and she would exercise every day in a way she enjoyed. Sophia: That sounds both liberating and terrifying. What was the result? Laura: Her weight stabilized. It settled at the top of her defended range and stayed there. She stopped worrying about calories because she learned to trust her body's signals. She says her hypothalamus is a much better calorie counter than her conscious brain ever was. Sophia: I love that. It reframes the goal. It's not about the number on the scale, but about the daily practices. So what are the core behaviors she recommends? Laura: It’s refreshingly simple. First, practice mindful eating. Pay attention to your body. Eat when you're hungry. Stop when you're full. Savor your food. Second, find a form of physical activity you genuinely love and do it regularly. Not as a punishment for eating, but as a celebration of what your body can do. Exercise is one of the best things for your health, regardless of whether you lose a single pound. Sophia: So it’s about decoupling exercise from weight loss. That’s a huge mental shift. Laura: A huge one. The book cites studies showing that fitness is a far better predictor of health and longevity than weight. A fit person in the "obese" category can be healthier than a sedentary person in the "normal" weight category. The goal is to build habits that last a lifetime, because a diet, by definition, is temporary. Sophia: This is all so empowering. It feels like permission to get off the roller coaster. Laura: It is. And it’s a powerful message that has resonated with so many people, which is why her work has become so influential. It’s a shift from self-criticism to self-care.

Laura: When you step back and look at the whole picture Aamodt paints, it's a stunning indictment of the entire diet industry. It’s an industry built on a fundamental misunderstanding of the brain. It sells us a war against ourselves that we are biologically programmed to lose. Sophia: A war that, as she shows, leaves us heavier and less healthy than when we started. The real tragedy is the amount of time, money, and mental energy that people pour into this losing battle. Laura: Think about it. The book points out that low fitness is responsible for about 16 percent of deaths in the U.S., while obesity itself only accounts for 2 to 3 percent once you factor out the effects of fitness. We are fixated on the wrong target. Sophia: And the solution she offers isn't a magic pill or a new fad diet. It's a return to something more intuitive and, frankly, more humane. It’s about listening to your body instead of shouting at it. Laura: The ultimate takeaway is that the path to well-being isn't about fighting our bodies, but about befriending them. It’s about trusting our internal signals and focusing on behaviors that genuinely nourish us, physically and mentally. Sophia: It makes you wonder, what could you accomplish with all the energy you've spent fighting your own body? What if you redirected that focus from the number on the scale to your actual life, your relationships, your joy? Laura: It's a powerful question. And a hopeful one. We'd love to hear your thoughts on this. Join the conversation on our social channels and let us know what resonated with you. Sophia: This is Aibrary, signing off.