David Kessler took GLP-1 drugs to help manage his weight. In his new book, he explains why the drugs are revolutionary, but not a panacea.
The following is an excerpt from Diet, Drugs, and Dopamine: The New Science of Achieving a Healthy Weight by David A. Kessler.
When you purchase products through the Bookshop.org link on this page, Science Friday earns a small commission which helps support our journalism.
Buy The Book
Diet, Drugs, and Dopamine: The New Science of Achieving a Healthy Weight
I am average. I am like everyone else. For most of my life, I have been in a battle with my body. I have been fat, and I have been thin, and I have been every size in between.
I am like the nearly three-quarters of the population who are either overweight or obese and have had their health jeopardized because of it. Since I was a kid, I’ve gained and lost weight repeatedly, putting on twenty pounds, taking it off, putting on thirty pounds, returning to the drudgery of restraint until I’d lost it again, only to gain the weight back once more. It has been a cycle of despair, repair, and back to despair.
No longer.
We can reclaim our health. Dramatic and lasting weight loss is possible. Anyone struggling with weight can lose the toxic fat that threatens our health—and keep it off. Let me be clear: It is this toxic fat—also known as visceral fat—that we carry in and around our organs that is the problem, not how big or small our bodies are.
We now have highly effective anti-obesity medications, otherwise known as GLP-1 (glucagon-like peptide-1) agonists. These drugs have revolutionized our understanding of weight loss, and of obesity itself. For too long, body weight has been shrouded in mystery. Why have so many of us gained weight? Why is it so hard to lose weight? And, if we do manage to lose it, why does it feel so impossible to keep it off?
The fact that the new anti-obesity drugs are highly effective underscores the fact that being overweight or obese is not a product of lack of discipline or willpower—a bias that has long prevailed, even within the medical profession. It is instead a product of biology. We know from clinical studies that these medications work largely by increasing satiety—or feelings of satisfaction or fullness after eating—and quieting “food noise,” that clamorous, food-focused chorus in our heads that plays on repeat throughout the day. Food noise comes from a preoccupation with and craving for food. When people stop taking anti-obesity drugs, these unpleasant experiences reemerge.
Preoccupation with and craving for food are also hallmarks of the addictive process. That chorus that plays in our heads is a result of the ultra-formulated food that has increasingly become the mainstay of our diets. Over the last fifty years, the food industry has glutted our grocery stores, delis, and corner markets with the irresistible, highly processed, highly palatable, energy-dense, high-glycemic foods—ultraformulated foods—that have quietly commandeered the reward centers of our brains. Put simply, these foods are addictive.
The widespread availability of these foods has created an ongoing insult to our brains, triggering our addictive circuits—causing cravings that can arise outside of awareness, as well as compulsive eating—and altering the neurohormones that control weight. As a result, our average weight settling point—that is, the weight range that the body naturally tends to gravitate toward—has increased. We are now caught between what the food industry has done to the American diet and what our metabolisms can accommodate. Being overweight or obese has essentially become our default setting, and, consequently, we have experienced a rise in the diseases and conditions that toxic fat causes, including arthritis, certain forms of cancer, blood clots, type 2 diabetes, hypertension, increased blood lipids, atherosclerotic heart disease, dementia, and stroke. It is a health catastrophe that has reached its apex on every level. Current projections do not indicate a significant change in longevity over the next three decades, but there will be a substantial rise in morbidity due to obesity. The culprit is not weight or body mass index (BMI) but visceral fat. By decreasing chronic diseases caused by visceral fat, we can improve lifespan and quality of life. In other words, a major key to our longevity is linked to losing this toxic fat.
How Do GLP-1 Drugs Override Our Biology?
And we have underestimated the very important role that food addiction plays in controlling our weight. Ultraformulated food is our new cigarette, and it is critical that we understand the changes that need to occur—in our lives, in our bodies—through this lens. “There is no free ride in the brain when you take drugs. No matter what drug you take,” as Dr. George Koob, director of the National Institute on Alcohol Abuse and Alcoholism, puts it. “If you keep eating highly palatable foods, you are changing the physiology of the body.”
Now, for the first time in medical history, using these anti-obesity medications, we can specifically modify the addictive neural pathways, allowing us to change our body weight in a decisive way. It is not uncomplicated, and it is not without risks. It is also not for everyone. And yet, for many people who have struggled long and hard with their weight—myself included—these drugs offer significant health and emotional benefits.
But make no mistake: There are no magic pills here. Prescribing these medications alone does not meet the standard of good medical care, and we have not yet figured out how to safely and practically use these drugs over the long term. Anti-obesity medications only work for the duration they are administered; appetite and weight return when they are stopped. Because of this, the pharmaceutical industry has positioned them as “forever drugs”—taken until death do you part—as, indeed, that strategy offers them billions in profits. For some people, this may be the right course of action. But I consider these drugs as only one powerful tool we can now use to manage our weight and our health. The other tools have been there all along: nutrition, behavioral therapies, and physical activity. When used together as a system, it is possible to reset weight in a healthy way in the modern world, and the change can be dramatic.
All these options, either on their own or in conjunction with one an- other, grant us the space we need—slowing us down enough to make more mindful choices—to bypass our addictive circuits and rebuild our eating patterns. “I think it’s really difficult for people to conceive of how hard it is to exist when you’re that obese,” said a patient advocate who studies nutrition and who himself lost more than 200 pounds by changing his eating pattern, but never took an anti-obesity drug. “The way I eat now is so much easier.” To a greater or lesser extent, this idea holds true for all of us. We have an array of tools to choose from to push back against the food addiction that characterizes our modern era. We can use these tools to disrupt that addiction and create the opportunity for sustainable weight loss.
Now that we have effective anti-obesity medications, the ways in which we engage with all these methods have changed. For example, because these drugs alter our food preferences, as well as drastically reduce the amount of food that we eat, it is critical that doctors who prescribe them also provide nutrition guidance. Unfortunately, most doctors are not trained in nutrition; there is a great deal about weight management that they are not equipped to handle.
Perhaps most crucially, effective treatment does require a lifelong commitment, but not in the way the pharmaceutical companies portray. Sustainable weight loss relies on a full range of methods over the course of our lifetimes. Realistically, then, the journey of weight loss and management requires choosing what works best for you, and understanding not only how to combine these various tools, but also how to change course if one begins to wane in effectiveness.
With this book, I hope to demystify a physiological process that has long provoked confusion and shame. The path to achieving a healthy weight should not be obscure, but clear, evidence-based, and compassionate. Losing weight and maintaining it will always be an individual journey, but there are certain truths that apply to us all. And for the first time, we are accumulating the research and information to know how best to use them. Let’s get started.
EXCERPTED FROM DIET, DRUGS AND DOPAMINE. COPYRIGHT © 2025 BY David A. Kessler, MD. EXCERPTED BY PERMISSION OF FLATIRON BOOKS, A DIVISION OF MACMILLAN PUBLISHERS. NO PART OF THIS EXCERPT MAY BE REPRODUCED OR REPRINTED WITHOUT PERMISSION IN WRITING FROM THE PUBLISHER.