Sunday, 29 July 2007

New book suggests obesity is all in the genes

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This past spring a new book by Gina Kolata, a science reporter for the New York Times, hit the scene -- Rethinking Thin: The New Science of Weight Loss - and the Myths and Realities of Dieting. I came across a mention of the book in the blogosphere and had to check it out. I have personally not read the book yet, but I have poured over newspaper and reader reviews.

In Rethinking Thin, Kolata argues being fat is biological destiny. She says most overweight people are stuck within a relatively narrow weight range set by their genes. But as obesity rates have steadily risen and the phrase 'obesity epidemic' sails across the news waves, the pressure to eat healthy, exercise and lose weight screams in response.

Kolata notes dieters only manage to keep off a little weight, sharing scientific evidence to explain this constant, disappointing phenomenon. Fat people have more fat cells, and while their metabolisms are normal, their appetites are larger. Losing significant weight often triggers a powerful "primal hunger." Furthermore, studies on twins and adopted children show inheritance may account for up to 70 percent of weight variance. Kolata leans heavily on the influence of genetics -- questioning the popular belief 'fat people can become thin if they would only apply themselves.' A similar argument is often applied to overweight people with type 2 diabetes -- 'just lose the weight already and you will be cured!' But if obesity is nearly all genetic, why are we getting fatter and fatter?

Emily Bazelon's book review in the New York Times is a nice overview of Kolata's arguments. Bazelon throws out a few challenges, pointing out Kolata ignores the influence of the 'gazillion-dollar food industry'. She also questions Kolata's speculation that obesity might be a response to modern medical advancements -- that our nation's improved early nutrition, vaccines or antibiotics might somehow change the brain's control over weight. This is an interesting line of thought, very different from the concept that our ancestral caveman's between-the-hunt survival biology simply cannot handle our country's overabundance of cheap, calorie-laden cuisine consumed in a car.

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