Diet, Health, Weight Loss And GLP-1 Drugs, According To David Kessler, M.D.

Former FDA Commissioner Dr. David A. Kessler, MD has had the rare distinction of being a bipartisan head of the U.S. Food and Drug Administration under both Presidents George H.W. Bush and Bill Clinton. A lawyer and pediatrician, he is a graduate of Amherst College, University of Chicago Law School, and Harvard Medical School, and has been the dean of the medical schools at both Yale University and the University of California, San Francisco. Most recently, he served as chief science officer of the White House COVID-19 Response Team under President Joe Biden. He is the author of several books, including multiple New York Times Bestsellers: The End of Overeating, Capture, Hijacked, Fast Carbs, Slow Carbs and A Question of Intent. Dr. Kessler is an expert on dietary topics and public health, and just (May 13, 2025) released his newest book, Diet, Drugs, and Dopamine: The New Science of Achieving a Healthy Weight. The subject is both very timely and very important, so I pre-ordered it and immediately dove in. He agreed to answer some questions about currently red hot issues in America, diet, health, weight loss and GLP-1 drugs.

According to the National Institutes of Health, about one in three Americans are overweight and two in five are obese. The NIH states that “Overweight and obesity increase the risk for many health problems, such as type 2 diabetes, high blood pressure, heart disease, stroke, joint problems, liver disease, gallstones, some types of cancer, and sleep and breathing problems, among other conditions.”

While the use of GLP-1 drugs such as Ozempic, Wegovy and Mounjaro is still relatively new for weight loss, the most recent (May 2024) Kaiser Family Foundation Health Tracking Poll showed that a stunning 12% of Americans had used these drugs, 16 million people, but the potential market is much larger and the numbers have almost certainly gone up substantially in the past year (Dr. Lipi Roy wrote about GLP-1 drugs and addiction here at Forbes recently).

Yet despite the much talked about obesity epidemic that has now gone on for decades, very little has changed in the science of nutrition and diet until recently. New evidence suggests that the long believed in model may be badly broken, and that issues previously relegated to willpower may in fact be simple human evolution and biology. Recent research in this vein, such as that espoused by scientist Herman Pontzer in his 2022 book Burn: The Misunderstood Science of Metabolism, posits that almost all diets fail, and it is not so much what we eat in terms of carbs, fat and such that matters, but rather that modern highly-engineered processed or ultra-processed foods bypass the body’s normally reliable self-regulatory system and fool our normal appetites and desire to be satiated.

MORE FOR YOU

Google’s New Android Update — 3 Things Your Phone Can No Longer Do

Microsoft Update Fails—New Download Breaks Windows

Microsoft Confirms Windows Upgrade Choice—You Must Now Decide

In a review of one of Dr. Kessler’s earlier books, Hijacked, How Your Brain Is Fooled By Food, literary site Goodreads wrote “until about 30 years ago, we did not have a weight problem in North America. In fact, throughout history, the human body weight stayed pretty much the same. People ate the amount of food they needed and no more. Then, in the 1980s, something changed. North Americans started gaining a lot of weight. What happened in such a short time to add so many millions of pounds to so many millions of people? Something had changed in North America, but it wasn't us. It was our food. These processed foods - loaded with sugar, fat, and salt - make it almost impossible for some people to stop eating.”

Or, as Dr. himself Kessler put it in a recent opinion piece for the NY Times, “For many of us, our biology makes the pull of these ultraformulated foods nearly impossible to resist. These foods typically are called ultraprocessed, but I refer to them as ultraformulated because they have been engineered to manipulate the brain’s reward system. These foods have become the new cigarette and, similarly, have resulted in a health catastrophe.”

I have written extensively about food, a healthier food supply, and buying and eating better quality food, and I devote a substantial amount of time to personal health, carefully monitoring my diet and exercise. But there is a lot of conflicting information right now on these topics, so I went to the expert with my questions about diet, health, weight loss and exercise.

Questions and Answers with Former FDA Commissioner Dr. David A. Kessler

Q: This is the big one everyone wants to know—why is it so hard to lose weight?

A: Traditionally, we have blamed the patient. The new anti-obesity drugs demonstrate that it is not a matter of willpower. It’s our biology at work. There are addictive and hormonal circuits at work. It is difficult to escape the pull of food addiction and overcome our brain’s built-in reward response to the ultraformulated foods that flood our food supply.

Q: You say in the book that we need to create a new paradigm for addiction. What do you mean by this?

A: The maladaptive shift in the brain that occurs because of addiction doesn't take place because the brain is not working properly, but because our brains are working too well by adapting to our environment. The human brain evolved to deal with scarcity, not abundance. For much of human history, there was no guarantee as to when our next meal would arrive, so our biological systems are designed to seek out the sweetest and most energy-dense foods. These systems are also designed to hold on to body fat for survival. Put simply, we are programmed to eat ultraformulated foods that are never scarce in our modem food environments.

Q: You use the term toxic fat in the body. What does that mean and what are the dangers of this type of fat?

A: Our bodies have experienced an insidious decline in health over the past half century that has been caused by never-ending consumption of foods that can trigger the addictive circuits. These foods have delivered not satisfaction, but a body that is burdened by visceral fat, which is also referred to as toxic, abdominal, or central fat. This metabolically active fat accumulates around the waist, surrounding and invading the heart, liver, and pancreas.

Q: Are the GLP-1 drugs the magic bullet we need?

A: Anti-obesity drugs have changed the landscape of weight loss. Their development provides us with an opening to reverse the epidemic of chronic disease. But the new GLP-1 drugs are not the panacea.

They work by causing us to eat less. In some cases, it is much less, which poses its own set of risks. The pharmaceutical companies have not leveled with the public that these drugs work in significant part by triggering gastrointestinal effects, keeping food in the stomach longer, generating feelings that border on nausea, and sometimes outright nausea, which in turn induce feelings of fullness and satiation. Those feelings counterbalance the rewarding and addictive properties of food. By countering the reward circuits, these drugs reduce the "food noise" that plays in the heads of many people who struggle with weight. People on these medications also condition themselves to eat less to avoid the ill effects of food staying in the stomach longer.

Q: What about diet and exercise, which we have always been told is so important. Is it still necessary to pay attention now that we have GLP-1 drugs?

A: Some physicians have publicly stated that diet and exercise alone are not enough to treat obesity and visceral adiposity, and that only medication and surgery are effective treatments. They are wrong. Diet and exercise are still the foundation of improved metabolic health. Medications are not the be-all and end-all solutions. They are tools that allow people to control appetite so that diet and lifestyle interventions can be effective.