David L. Katz SPH ’93 is founding director of the Yale Prevention Research Center at the Yale University School of Medicine and editor-in-chief of the journal Childhood Obesity. In response to the American Medical Association’s June 2013 decision to officially recognize obesity as a disease, Katz published a piece in the April 17 edition of Nature entitled “Obesity is not a disease.” The News sat down with Katz to discuss his argument that classifying obesity as a “disease” could negatively impact efforts for its prevention.
Q. Can you describe the way that obesity is different from a disease?
A. I often compare obesity to drowning. Would we consider it a disease if a person were drowning? When someone is drowning, it’s not a problem with their body: Humans cannot be in the water for an arbitrary amount of time, so the problem is a mismatch between the body and the body’s environment.
I think drowning and obesity share many important characteristics. Both are about an interaction between a perfectly healthy body and the challenge of an environment in which they are maladapted. In both cases, you’re exposed to something that’s initially a good thing, but you’re exposed to too much of it for too long. In the case of water, you need it, but too much of it for too long and you drown. In the case of food, if you eat too much of it for too long, then you get fat.
In both cases, absolutely everybody is vulnerable, but people are vulnerable to varying degrees. If we’re put underwater, eventually all of us will drown, but some of us are able to hold our breath longer than others. I think that’s true about obesity: About 80 percent of the adult population of the United States is either overweight or obese. That indicates that essentially, we’re all vulnerable, but we’re not all vulnerable to the same degree.
Q. Using your comparison of drowning and obesity, can you elaborate on your argument that obesity prevention should be emphasized?
A.We don’t ignore the things that cause people to drown and just wait for them to show up in the emergency room. The focus is on preventing drowning in the first place — lifeguards, swimming lessons, fences around the pool — there is a whole array of strategies that recognizes the fact of drowning. Potentially, the interaction between people and water can turn deadly, and so we need to address the places where that interaction takes place in order to protect people there.
The corresponding places with regards to obesity would be supermarkets and restaurants, schools, work sites — basically all the places where people spend their time and make decisions about food and physical activity. We could do that — we could say that we need the food and exercise equivalents of lifeguards and swimming lessons — and we should. If we did, obesity rates would plummet. I really worry that in the effort to make obesity medically legitimate, we will become overly preoccupied with the medical approach and if we do that, we’ll be diverting resources from prevention and from other diseases and become totally focused on inventing the next “wonder drug.”
Q. Can you expand on the idea of an obesity “wonder drug,” and more broadly, existing medical treatments for obesity?
A. I don’t think we’re ever going to come up with a wonder drug to fix obesity. Imagine trying to come up with a drug to prevent people from drowning — how completely radically that would have to alter human physiology. If you take a pill that’s going to allow you to stay underwater for an hour and not drown, that’s going to basically need to be a pill that turns you into a fish. Anything that doesn’t go that far is going to fail, and anything that does do that is pretty horrible to think about — it’s basically turning a human being into something other than a human being.
A pill to fix obesity is much the same: We probably aren’t getting fat because there’s some element of our physiology that has run amok. We’re probably getting fat because of numerous, intricate, overlapping metabolic checks against starvation. Everything that humans eat is to defend against starvation, because that has been a threat throughout all of human history.
When we create a drug, one of two things happen. Either the drug doesn’t work very well because there are compensatory mechanisms built into our physiology so that if you tweak one hormone level, other hormone levels fluctuate to compensate, or you quickly encounter an array of unintended consequences.
Q. Is it still possible for us to focus on prevention if obesity doesn’t lose the disease label?
A. I think there’s hope. After all, Nature is one of the preeminent medical journals on the planet, and they asked me to write this commentary. My hope is that we are becoming more focused on the importance of obesity, that we are recognizing the legitimacy of obesity, but that labeling obesity as a “disease” is simply creating an opportunity for dialogue we didn’t have before, and ideally we won’t be committed to obesity as a clinical condition and a disease that needs a drug. I know that some people want that. The drug companies want that. But for the most part, our society can’t afford that. Obesity is rampant not only in adults, but also children. Are we talking about drugs that everyone in the family takes, every day for the rest of their life? Could society possibly deal with the cost of everyone getting pharmacotherapy or bariatric surgery?
I’m a little worried because we do have a tendency in the US to over-medicalize things. We need to think of obesity in terms of its roots in our lifestyle, recognizing the problem naturally and then helping people before they get in trouble, before we try to change the body.