Rethinking Thin: The New Science of Weight Loss—and the Myths and Realities of Dieting, by Gina Kolata, New York: Farrar, Straus, and Giroux, 257 pages, $24
Mindless Eating: Why We Eat More Than We Think, by Brian Wansink, New York: Bantam Books, 276 pages, $25
Gina Kolata says losing weight is nearly impossible. Brian
Wansink says it’s easy. But they don’t really contradict each
other, because they’re talking about different kinds of weight
Although their new books offer very different messages for dieters, Kolata and Wansink share a suspicion of collectivist responses to the “obesity epidemic.” Both writers are intensely interested in the question of why people weigh as much as they do, but they do not leap from research findings to policy prescriptions aimed at making us thinner by restricting our choices. At a time when almost every discussion of weight in America seems to end with a list of things the government should do about it, their restraint is commendable.
In Rethinking Thin, Kolata, a veteran New York Times science reporter, focuses on a group of obese people enrolled in a University of Pennsylvania diet study. They exhibit the usual pattern of initial success followed by setbacks, typically ending up about as fat as they were to begin with. She uses these case studies to illustrate her general point that “very few people lose substantial amounts of weight and keep it off” because genetic factors play a large role in determining how much a given person will weigh as an adult.
By contrast, in Mindless Eating, Wansink, a marketing professor at Cornell University who has studied consumers’ food-related decisions for decades, focuses on the sort of gradual, modest weight loss that Kolata concedes is achievable. Declaring that “the best diet is the one you don’t know you’re on,” he urges small changes in everyday behavior that over the course of a year can result in a weight loss of 10 to 25 pounds. His book will not be much help to people like the research subjects Kolata interviews, who generally want to lose 50 to 100 pounds.
Kolata’s message, as it pertains to the very fat, is mostly discouraging, while Wansink’s, which is addressed mainly to the somewhat overweight, is relentlessly upbeat. But both distinguish themselves from the “obesity epidemic” doomsayers by casting a skeptical eye on efforts to make Americans thinner through social engineering. They show that it’s possible to discuss the issue of weight without laying out a Plan of Action that treats us all as an undifferentiated blob of blubber.
Kolata, whose reporting on subjects ranging from breast implants to pesticide residues has been admirably resistant to the health scare du jour, questions the conventional wisdom that weighing “too much” is unhealthy. Like other dissenters from the War on Fat, such as University of Colorado law professor Paul Campos and University of Chicago political scientist Eric Oliver (see “Lay Off the Fatties!,” November 2006), she tells fat people they will probably stay that way but simultaneously reassures them that the medical implications are not as dire as they’ve heard.
Many of the health risks associated with obesity may be due to the poor diets and sedentary habits associated with fatness rather than the extra pounds per se. Kolata notes that it’s unclear whether exceeding the government’s recommended weight range is inherently hazardous or whether fat people who become thinner thereby become healthier. Yet scientists who point out such inconvenient facts can expect to be pilloried for failing to toe the party line. Kolata describes the dismay of two researchers at the U.S. Centers for Disease Control and Prevention, Katherine Flegal and David Williamson, at the anger they provoked from their colleagues by suggesting that the death toll the government had attributed to excessive weight was greatly exaggerated.
In a 2005 study published by The Journal of the American Medical Association, Flegal, Williamson, and two other researchers reported that people the government considers “overweight” have lower mortality rates than people with supposedly “healthy” weights. They were criticized not so much for being wrong as for being unhelpful. “Your patients likely did not read the original article,” said an editorial in the journal Obesity Management, “but they did likely hear about it in the news and the message they got was not to worry so much about overweight and obesity. I do not think this is the message you want them to have.” That response was typical, Flegal tells Kolata: “Everyone thinks they already know the answer.…All these people who just know weight loss is good for you. It’s just taken for granted regardless of the evidence.”
So is the feasibility of major, permanent weight loss, Kolata argues, for the most part persuasively. Her litany of diet fads, ranging from Jean Anthelme Brillat-Savarin’s 1825 bestseller The Physiology of Taste to The Atkins Diet Revolution, The Zone, and The South Beach Diet, shows that hope springs eternal in the plump torso, a point confirmed by her often poignant personal histories of dieters. A fat man who, like most of the subjects in the University of Pennsylvania study, has tried many different diets, losing and regaining hundreds of pounds, tells her: “In your brain, you say, ‘I have 100 percent free will. I have total control over what I eat.’ But in the experience of my life, in the experience of my day, in the experiences that have been thrust upon me, I don’t have that control.”
Kolata’s discussion of obesity research suggests that false hope is not limited to people trying to lose weight. Scientists too are perpetually reaching for a weight loss key that always seems just beyond their fingertips: the right diet, the right drug, the right hormone.
Kolata’s main explanation for the failure of these efforts is that people are genetically programmed for a certain weight range, which varies widely from one individual to another. Twin studies indicate that genetic differences account for something like 70 percent of variation in weight. “The body’s metabolism speeds up or slows down to keep weight within a narrow range” of “20 to 30 pounds,” Kolata writes. While losing 20 or 30 pounds would count as success for most Americans whom the government considers overweight, it would be just a start for the study subjects on whom Kolata focuses.
The idea of predetermined weight ranges is consistent with much everyday experience: People tend to return to a particular weight after gaining a few pounds from holiday overeating, for example, or after losing pounds during an illness. It also jibes with the complaints of people who say they easily gain weight while friends can eat whatever they want and stay thin.
Kolata describes research that backs up these anecdotes, including experiments showing the difficulty that thin people have in gaining weight as well as the difficulty that fat people have in losing it. In both cases, the weight tends to spring back after the experiment is over. One reason: Fat people have more fat cells than thin people, and when they lose weight the cells don’t disappear; they just get smaller. Likewise, thin people have fewer fat cells, and when they gain weight the cells don’t multiply; they just expand. Partly because of the signals sent by these fat cells, but also because of how those signals are conveyed to and interpreted by the brain, obese people do not feel satiated as soon as thin people do.
There is also evidence that their hunger is more intense. Kolata notes that the food-obsessed, sneaky, guilt-ridden behavior of fat people on diets is similar to the behavior of thin experimental subjects who are deliberately underfed. “A lot of thin people think that because they can skip a meal and feel a bit hungry, everyone can do the same,” one obesity researcher tells her. “They assume the sensation of hunger is the same for everyone.” They’re wrong, says Kolata: “Fat people are fat because their drive to eat is very different from the drive in thin people.”