It’s Obesity That Causes Overeating, Not the Other Way Around

Bob Kushner knows a thing or two about the complexity and challenge of obesity and clinical care for this disease. He’s written 15 books, 56 chapters, and hundreds of scientific articles about it. But the unique thing he brought yesterday was a skill for explaining the complexity of obesity in plain language that real people can understand. In the course of an impressive opening presentation at YWM2025 on the science of obesity, he turned conventional (and mistaken) thinking about obesity upside down with a simple statement. “Overeating does not cause obesity. Obesity causes overeating.”

This is something we heard years ago at the Blackburn Course in Obesity Medicine from Lee Kaplan. It was true then and it’s just as true today. But people forget.

Looking for a Culprit to Blame

Lately, headlines have bombarded us with messages that point in the opposite direction. Lately, a study in PNAS about energy expenditure and obesity across the economic spectrum has been prompting these headlines:

Overeating is roughly 10 times more important than a lack of exercise in skyrocketing obesity rates

Obesity more likely caused by high calorie diet than lack of exercise

What really causes obesity? Study says diet matters more than exercise

Food policy activists latched right onto this. “This study confirms what I’ve been saying, which is that diet is the key culprit in our current epidemic,” said one of them in the Washington Post.

But we know that obesity and its rise in the population does not simply have a switch that someone flipped to cause this problem. It’s a nice fantasy, but we can’t solve the problem by flipping the ultra-processed food switch to the “off” position. No, the rise of obesity is a wickedly complex problem. Kushner said it plainly in the Q&A for his session:

“They’re wrong. Obesity does not have a single, simple cause.”

An Obesity Care Dividend

But here’s the thing. We now have options for obesity care that can help people tremendously. Kushner explained that “GLP-1 medications have been transformative in the treatment of obesity. They address the underlying biology of appetite dysregulation.”

No, they do not work for everyone. Newer medications are on the way and we have good reasons for hope that these new medicines will help even more people. We also have some work to do on the cost burden of these medicines so that more people can afford access to them. This is one more reason obesity is such a wicked problem to solve.

But guess what. As these new medicines address the problem obesity causes with appetite regulation, it is becoming ever more clear that these medicines are beginning to prompt changes in our food environment. People have less of a taste for ultra-processed food that might harm their health. It’s prompting food companies to adapt and look for ways to sell healthier products.

We will call this an obesity care dividend.

Click here for the slides from Kushner’s presentation, here and here for more on the obesity care dividend showing up in the food industry. For more on the leap of faith from the article in PNAS, click here.

Bob Kushner at YWM2025, photograph by Ted Kyle / ConscienHealth

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July 26, 2025