Virginia Hughes examines the links between body weight and health:
Some researchers contend that what really matters is the distribution of fat tissue on the body, with excess abdominal fat being most dangerous; others say that cardiovascular fitness predicts mortality regardless of BMI or abdominal fat. “BMI is just a first step for anybody,” says Steven Heymsfield, an obesity researcher and the executive director of the Pennington Biological Research Center in Baton Rouge, Louisiana. “If you can then add waist circumference and blood tests and other risk factors, then you can get a more complete description at the individual level.”
If the obesity-paradox studies are correct, the issue then becomes how to convey their nuances. A lot of excess weight, in the form of obesity, is clearly bad for health, and most young people are better off keeping trim. But that may change as they age and develop illnesses. Some public-health experts fear, however, that people could take that message as a general endorsement of weight gain.
In a follow up, she discusses obesity with molecular biologist Jeffrey Friedman:
Each of us, he argues, has a different genetic predisposition to obesity, shaped over thousands of years of evolution by a changing and unpredictable food supply. In modern times, most people don’t have to deal with that nutritional uncertainty; we have access to as much food as we want and we take advantage of it. In this context, some individuals’ genetic make-up causes them to put on weight — perhaps because of a leptin insensitivity, say, or some other biological mechanism.
In other words, morbidly obese people lost the genetic lottery. “The irony is, it’s the people who are the most obese who are stigmatized the most, and in fact, they’re the people who can do the least about it,” Friedman says.