In this week’s episode, find out what everyone gets wrong about weight loss. Why don’t diet and exercise work very well? Do official guidelines and weight loss drugs offer a clearer path to success?

With nearly three-fourths of American adults either overweight or obese, we can’t ignore the problem any longer. For decades, people have acted as though packing on extra pounds was simply a matter of poor willpower. “Eat less and exercise more” is the standard mantra. But that is just one of the things we get wrong about weight loss.

In truth, obesity is far more complex than we may imagine. In fact, neuroendocrinologist Robert Lustig has spent decades studying obesity and diabetes in children. During the past 25 years, the weight of newborn babies has risen by about 200 grams.

No reasonable person could imagine this is the babies’ fault! As a result, he says we need to grapple with the concept of different obesities with different causes and diverse consequences. When we come to terms with what we get wrong about weight loss, we may be able to start helping people achieve it.

Dr. Lustig points out that not all fat is identical. In fact, the most visible fat depot, the subcutaneous fat, may be the least dangerous. Many people could handle as much as 20 pounds of subcutaneous fat visible on the arms, legs or butt without serious health consequences.

Visceral fat, wrapped around the internal organs, is associated with high cortisol levels much more than with overeating. As little as 2 pounds of visceral fat could make trouble.

However, the deadliest fat depot is the liver. As little as ½ pound of fat in the liver can damage health. Dr. Lustig traces fatty liver to overconsumption of alcohol or sugar. Fructose, an important component of sugar, is one of the bad actors driving the epidemic of non-alcoholic fatty liver disease among children (Nature Reviews. Gastroenterology & Hepatology, May, 2010).

The obesities can increase our risk for a number of serious conditions, including hypertension and diabetes as well as metabolic syndrome and heart disease. Fatty liver disease, whether associated with fructose or alcohol consumption, can damage the liver and lead to cirrhosis. It also triggers severe inflammation and is linked to a greater chance of kidney disease.

Every cell in our body relies on mitochondria to produce its energy. These tiny organelles take the energy from food and turn it into ATP, the form of chemical energy that our cells need to function. Unfortunately, the fructose in sugar or high-fructose corn syrup can mess mitochondria up in the context of a high-fat diet (Cell Metabolism, Oct. 1, 2019).

Recently, people have gotten excited about the potential for drugs originally designed to treat type 2 diabetes to help people with significant weight loss. Medications like semaglutide, sold as Ozempic or Wegovy, have become so popular that there have been shortages.

Dr. Lustig discusses their use and the symptoms that may be associated with them. Importantly, such drugs can lead to weight loss, up to 16% of total body weight in some studies. However, many people report nausea, sometimes vomiting, lack of appetite and diarrhea. Perhaps we should not consider these side effects; they may be contributing to the effectiveness of the drugs. (Dr. Lustig points out that if people are provided with a healthier diet of real food, they can reduce their risk of metabolic disorders by 29 to 45 %.)

Earlier versions of these GLP-1 analogs such as exanetide (Byetta) may increase the risk for pancreatic cancer or certain types of thyroid cancer. We don’t yet know if Wegovy will have similar risks. But we do know that when people stop taking one of these pricey pills, they often gain the weight back. You can read more about this “boomerang” effect at this link.

Dr. Lustig points out that the subsidies that the US provides to major food companies mean that ultra-processed foods containing corn syrup or sugar are cheap. As a result, many Americans rely on these inexpensive sources of calories instead of paying more for real food. But they are paying a price far beyond dollars and cents, because the cheap and easy foods are making Americans fat. Can we get food companies to do the right thing?

School cafeterias across the nation serve kids a tremendous amount of junk food, like pizza or potato chips. But they don’t have to. Dr. Lustig and his colleagues operate a pilot program with schools that serve real food instead. Happily, they do not have to increase their budgets to do so.

Providing youngsters with tasty real food can set them up for success in resisting weight gain as they grow older. Finally, we ask Dr. Lustig what people can do to help themselves with healthful, lasting weight loss.

Dr. Robert Lustig

Robert H. Lustig, MD, MSL, is Professor emeritus of Pediatrics in the Division of Endocrinology at the University of California, San Francisco (UCSF). He specializes in the field of neuroendocrinology, with an emphasis on the regulation of energy balance by the central nervous system. His research and clinical practice has focused on childhood obesity and diabetes. Dr. Lustig is the author of several books, including his most recent, Metabolical: The Lure and the Lies of Processed Food, Nutrition, and Modern Medicine.  You may also be interested in his previous books, Fat Chance and The Fat Chance Cookbook as well as The Hacking of the American Mind. His website is https://robertlustig.com/

The nonprofit organization improving food in schools is https://eatreal.org/

The podcast of this program will be available Monday, May 19, 2025, after re-broadcast on May 17. You can stream the show from this site and download the podcast for free.

Download the mp3, or listen to the podcast on Apple Podcasts or Spotify.