Is the obsession with obesity (and thinness) overblown? By Emily Bazelon
Friday, May 4, 2007
Rethinking Thin The New Science of Weight Loss - and the Myths and Realities of Dieting By Gina Kolata 257 pages. $24. Farrar, Straus & Giroux. If you had to choose, would you rather be fat or blind? When a researcher asked that question of a group of formerly obese people, 89 percent said they would prefer to lose their sight than their hard-won slimness. "When you're blind, people want to help you. No one wants to help you when you're fat," one explained. Ninety-one percent of the group also chose having a leg amputated over a return to obesity.
This is shocking. But it seems less so by the end of "Rethinking Thin," a new book about obesity by Gina Kolata, a science reporter for The New York Times. Kolata argues that being fat is not something people have much control over. Most people who are overweight struggle to change their shape throughout their lives, but remain stuck within a relatively narrow weight range set by their genes. For those determined to foil biology, strict dieting is a life sentence. "I am a fat man in a thin man's body," an M.I.T. obesity researcher who shed his pounds years ago tells Kolata.
He is one of the lucky and single-minded few. Study after study, Kolata notes, has shown that for most fat people the long-term rewards of dieting are modest at best. Yet as obesity rates have skyrocketed, exhortations to eat right, exercise and shed pounds have gone from loud to shrill. Kolata's understandable sympathy for those caught between the ever intensifying pressure to be thin and the stubborn size of their bodies, however, leads her to flirt with an unlikely conclusion: Maybe the outcry over obesity is itself supersized, and being fat isn't really unhealthy after all.
Kolata follows a two-year clinical trial at the University of Pennsylvania designed to test the low-carbohydrate, high-fat Atkins diet against a traditional low-calorie, low-fat one. Kolata wrote her book before she had the results for the trial, though a different study, published in March in The Journal of the American Medical Association, found that Atkins beats the low-cal diet for keeping off weight. The diet-versus-diet contest, however, isn't her real story. Instead, she focuses on how little weight those who follow any diet usually manage to keep off. (The average participant on the Atkins diet reported in JAMA lost only 10 pounds, or 4.5 kilograms, over the course of a year.)
Kolata tells the stories of four dieters in the University of Pennsylvania trial who are smart and likable. They had the benefit of a professionally led support group and the status of taking part in a well-financed study. They started exercising; they stopped eating mindlessly. After two years, they are a bit lighter. But none achieved the 50- to 100-pound weight loss they strove for.
Kolata marshals scientific evidence to explain why keeping weight off is so difficult. (The discovery last month of a garden-variety "fat gene" further backs her up.) Fat people have more fat cells than other people. Their metabolisms are normal but their appetites are larger. After they lose a significant amount of weight, one researcher explains, they often feel "a primal hunger" as strong as the urge a thirsty person feels to drink. Studies of twins and of adopted children show that inheritance may account for as much as 70 percent of weight variance. In one study of adopted children, 80 percent of those with two obese birth parents became obese, compared with 14 percent of those with birth parents of normal weight - and it didn't much matter what the adoptive parents fed the kids.
Given such proof of the power of genetics, Kolata asks, why do we continue to insist that fat people can become thin people if they only put their minds to it? She's surely right to push back against baffle-ment and intolerance, and her argument that we've tilted too far toward blaming fat people's bad habits for their weight is convincing. But Kolata goes so far in arguing for biological predestination that she sometimes seems to completely dismiss the other part of the fat equation - what people eat. In all likelihood, the obesity rate has doubled in the United States since 1980 for all the familiar reasons: fattening food has never been so cheap, convenient and cunningly marketed. "The genes that make people fat need an environment in which food is cheap and plentiful," she writes. It's in a world of giant muffins and bowls of office candy that Americans need wider movie seats and larger coffins.
Kolata knows this. She touches on reasons that poor people are more likely than rich people to be overweight, all of them environmental. But she treats childhood obesity as virtually inevitable.
She cites research showing that teaching kids to eat right in school, and serving them leaner lunches, has no effect on their weights. The researchers concluded that the intervention was too limited - the children's diets needed to change at home as well as at school. But Kolata scoffs at the "popular solution," which is "not to question the premise but rather to increase the intensity of the intervention."
Given the rise in obesity, however, is it really credible to put all the blame on our genes - and ignore the gazillion-dollar food industry? And while it's useful to point out that obese people don't have higher rates of anxiety, depression or mood disorders, that doesn't mean these conditions are never a factor in causing obesity in those who are genetically susceptible to it. As some of the testimony of Kolata's own dieters attests, we eat not just because our appetites drive us to but because our psyches do, in search of both pleasure and relief from pain or stress.
Kolata questions whether the current alarm over obesity is overblown - and whether the culture of dieting isn't itself harmful. The fat wars are less a legitimate public health campaign than a "moral panic," she suggests. In fact, she argues, some recent epidemiological studies show lower death rates for somewhat overweight people than for "so-called normal-weight people" or very thin ones.
The data are certainly intriguing. But living longer doesn't mean that fat people are in good health. In fact, they suffer from higher rates of diabetes, stroke, certain cancers and heart trouble. Kolata skirts this, because her argument is that thinness in and of itself is not a goal many people can achieve, or even an important one.
Kolata ends on a quixotic note, by wondering if perhaps Americans weigh more for the same reason that they are taller on average than they were a century ago - because they're in better health.
No one has found the smoking gun in the mysterious fattening of America, but Kolata, following the obesity researchers Jules Hirsch and Jeff Friedman, briefly speculates whether, say, better early nutrition, vaccines or antibiotics somehow "precipitated changes in the brain's controls over weight." It's a twist on the usual evolutionary argument. The problem isn't that people evolved to store fat in times of famine and now can't handle a 24-hour, all-you-can-eat buffet of abundance. People are fat because they're changing in response to the medical strides that have taken place.
A nice idea, maybe, but one as yet unsupported by evidence. What's more persuasive is Kolata's contention that we should replace the elusive goal of thinness with the goal of better health and greater happiness. Here her argument is eminently sensible: Sure, shape up your body. But mostly, make your peace with it.
Emily Bazelon is a senior editor at Slate.
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