The Mathematician’s Obesity Fallacy

Michael Moyer in Scientific American:

As I write, this interview with mathematician Carson C. Chow is the number-one most-emailed story on theNew York Times Web site. Chow, a researcher at the National Institute of Diabetes and Digestive and Kidney Diseases, had no experience in the health sciences before he came to study the problem of why so many Americans are overweight. “I didn’t even know what a calorie was,” he says.

This kind of outsider’s perspective can be invaluable when attacking a problem as difficult and entrenched as the epidemic of obesity in the U.S. Chow relates the story of starting work at the institute—a division of the National Institutes of Health—and finding a mathematical model created by a colleague that could predict “how body composition changed in response to what you ate.” The problem, as Chow describes it, was that the model was complicated: “hundreds of equations,” he told the Times. “[We] began working together to boil it down to one simple equation. That’s what applied mathematicians do.”

And what did Chow’s simple model reveal about the nature and causes of obesity? Basically, that we eat too much. “The model shows that increase in food more than explains the increase in weight.” Food in, fat out. Simple enough to be captured in a single equation.

Unfortunately Chow’s outsider’s perspective on the obesity crisis isn’t really an outsider’s perspective at all: it is the physicist’s perspective.

More here.