Is obesity really a disease? It's complicated.

I have a new opinion piece out in the New York Times today about the question of whether obesity truly constitutes a disease. I used to think it clearly is one. But the more I’ve learned about this debate in medicine, the more unsure I’ve become.

The issue here isn’t whether obesity has health consequences; it most certainly does. The issue is that, decades into what’s often referred to as the obesity epidemic, the medical community has never bothered to define obesity the illness. As I write:

It’s typically understood as an excess of body fat, using body mass index, or B.M.I., to gauge who has too much. But B.M.I. — a person’s weight divided by the square of their height — was never meant to be used as a diagnostic tool and can’t determine whether someone is healthy or sick. And there’s no consensus on the signs and symptoms that make obesity an illness the way high blood sugar levels are used to diagnose type 2 diabetes, or chest pain and irregular imaging to tell if someone has heart disease.

The imprecision is a major reason why other countries, including Denmark — home to Novo Nordisk, maker of drugs like Wegovy and Ozempic — don’t consider obesity a disease. In the essay, I also argue that the murkiness has allowed the myth that obesity is a personal choice to fester, harmed patients, and set obesity healthcare and policy back decades.

The good news: because of the medications, the medical community is finally grappling with the diagnosis question. A more precise definition of obesity is on its way.

Once the diagnosis issue is resolved, there will be more difficult questions to tackle — like how to help people who are sick with obesity now and prevent others from developing it. That’s when we exit the clinical realm and get into public health.

One patient who had been using Mounjaro for weight loss told me she discontinued the drug this year after realizing she’d have to use it for life to keep her weight down, which didn’t sit well with her. The experience left her wondering whether emphasizing obesity as a disease has, paradoxically, made individuals responsible for addressing it when obesity’s drivers are clearly environmental. “I realized it’s not just about my body,” she said. “It’s about the whole social construct we live within. It is about the food we eat, and the work we do, and the places we live, and the screens we’re on.”

“Why,” she wondered, “are we as a whole society not making an effort to address those, when it’s a whole society problem?”‌

Here’s the link to the full piece.