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 loss.
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."
In Kolata's view, that point is not contradicted by the fact that some people, such as former Arkansas governor (and current GOP presidential candidate) Mike Huckabee, have gone from obese to thin and managed to stay that way. It can be done, she concedes, but it takes a strong exercise of willpower—more willpower than most people need to avoid being obese in the first place—and a lifelong struggle. The fact that people like Huckabee are famous for losing a lot of weight (more than 100 pounds in his case) and keeping it off suggests how rare that accomplishment is, as does obese people's eagerness to undergo radical weight-reduction surgery that messes around with their stomachs and intestines. "In trying to lose weight," Rockefeller University obesity researcher Jeffrey Friedman writes in an article Kolata quotes, "the obese are fighting a difficult battle. It is a battle against biology, a battle that only the intrepid take on and one in which only a few prevail."
But predetermined weight ranges take us only so far. They do not explain why some people are thin for decades and obese thereafter. Nor do they account for the "obesity epidemic" of the last few decades. According to data from the National Health and Nutrition Examination Survey (which includes actual measurements of height and weight), the share of American adults who qualify as obese has more than doubled since the late 1970s, reaching 33 percent by 2004. The official cutoff for obesity is based on body mass index (BMI), which is weight in kilograms divided by height in meters squared. A man who is five feet, nine inches tall—me, for example—is deemed obese at a BMI of 30, equivalent to a weight of 203 pounds.
Meanwhile, the share of Americans who are considered merely "overweight," with BMIs from 25 to 29.9 (170 to 202 pounds for me), has increased only slightly, hovering around a third. At 175 pounds, I am "overweight" but not "obese," with a BMI of 25.8. If I lost six pounds, as my doctor has advised me to do, I would achieve the magical BMI of 24.9, giving me a "healthy" weight. But if I fail to do so, I suppose I shouldn't feel too bad, since two-thirds of American adults weigh more than the government thinks they should.
Although almost all of the BMI shift has occurred in the "obese" category, that doesn't mean the weight gains have been big. If I weighed 202 pounds, for example, and gained a pound, that would make me obese instead of just overweight. So small changes in weight in large numbers of people, shifting some from "healthy" to "overweight" and others from "overweight" to "obese," would be enough to account for the BMI trends bemoaned by public health officials. In other words, the "obesity epidemic" is not necessarily inconsistent with the idea that adults tend to stay within a 20-to-30-pound weight range.
Still, the question remains: Why did so many people gain weight during the 1980s and '90s? Since it takes longer than a couple of decades for genetic predispositions to change, Kolata suggests that early-life factors such as better nutrition, vaccination, and the availability of antibiotics somehow affected "the brain circuits that control eating" in people who came of age during the last few decades. But this hypothesis is highly speculative, with only limited animal studies to support it. For reasons that are unclear, Kolata rejects more plausible explanations, implying there's no evidence that Americans are eating more or exercising less than we used to. But that's not quite true.
In addition to weighing and measuring people, the National Health and Nutrition Examination Survey asks them what they eat. These numbers indicate that food consumption by both men and women jumped by about 200 calories a day between the late 1970s and the late '80s to early '90s. Self-reports on this subject may not be completely reliable, but the increase is striking, especially since it coincides with a spike in obesity.
As for calorie expenditure, a 2005 National Academy of Sciences report found that, contrary to popular belief, survey data do not indicate a decline in exercise during leisure time in the last few decades. But the report also noted that American jobs, housework, and transportation became less and less physically demanding throughout the 20th century, resulting in "a substantial decline in physical activity levels in the workplace, at home, and in travel over a long period." Although this trend is by no means restricted to the 1980s and '90s, it suggests that we could be burning fewer calories overall even if we are spending just as much time deliberately exercising. Modest increases in calorie consumption and/or decreases in calorie expenditure would be enough to cause the seemingly dramatic shift in weight the government has labeled an "epidemic."
Enter Brian Wansink. He's all about little changes that add up over time. He concedes that the body resists big, sudden movements in weight. "It's estimated that over 95 percent of all people who lose weight on a diet gain it back," he writes. "Deprivation diets don't work for three reasons: 1) Our body fights against them; 2) our brain fights against then; and 3) our day-to-day environment fights against them." Wansink's recommendations, which are derived from his research on the cues that lead people to overeat, are designed to achieve the loss of up to half a pound a week, which he says is below the threshold that would trigger a metabolic response. He urges readers to use "the mindless margin"—the 100 or 200 calories a day they would not really miss if they gave them up—to gradually move toward the bottom of their weight ranges.
Even if you have no interest in following Wansink's advice, the book is worth reading for his breezy, entertaining accounts of Candid Camera–ready studies in which people stuff themselves with stale popcorn because it's in a big container, keep slurping soup from a surreptitiously replenished bowl, or eat more in restaurants because of music, menu language, or the ostensible origin of a complimentary glass of cheap red wine. Wansink's overarching point is that, when it comes to food, we're not paying attention. "It takes up to 20 minutes for our body and brain to signal satiation," he notes, and Americans often finish their meals in less time than that. Instead of internal signals we rely on external cues to tell us when we're done: Is the plate clean? Is everyone else done? Is there more in the serving dish?
To counteract such cues, Wansink recommends such tactics as using smaller plates (which make portions seem larger), keeping serving dishes in the kitchen (which discourages second helpings), replacing short, wide glasses with tall, thin ones (which make drinks seem bigger), keeping food scraps and bones on your plate (which reminds you how much you've eaten), and dividing snacks from big packages into smaller bags or plastic containers (which discourages you from devouring the entire package). Wansink, who wants readers to know that he "enjoys both French food and French fries each week," advocates eating more mindfully, to increase enjoyment as well as to improve nutrition. But he thinks it's unrealistic to expect people to constantly count their calories in the face of the myriad food-related decisions they make each day. In his view it pays to plan ahead, in effect tricking yourself into eating less.
Despite their differences in tone and focus, Kolata and Wansink are equally unenthusiastic about proposals by fat warriors such as Yale obesity expert Kelly Brownell to reshape Americans by reshaping our "food environment" through propaganda, censorship, taxes, and regulation. Kolata says there's no reason to think the government knows how to make people thinner. She notes that even well-funded, intensive efforts aimed at slimming down captive audiences of schoolchildren have produced disappointing results, making proposals such as restricting cereal commercials, banning soda machines from schools, and distributing federally funded fruit to students look even lamer.
Wansink, for his part, says labeling and education don't make much of a difference, and "we cannot legislate or tax people into eating Brussels sprouts." Although he has spent much of his career studying ways in which businesses encourage people to buy, he recognizes the limitations of these techniques and does not portray them as inherently sinister. "Do food companies put ingredients in their food that they know we will eat and love?" he writes. "Absolutely—they are guilty as charged. So is your grandmother." Wansink emphasizes consumer self-help rather than protection from conniving capitalists. A chapter called "The Hidden Persuaders Around Us," a phrase that echoes the title of the 1957 Vance Packard book that portrayed advertisers as insidious manipulators of desire, is mostly about tricks people can use to avoid eating mindlessly. Instead of remaking the world to discourage overeating, Wansink says, "we can reengineer our personal food environment to help us and our families eat better."
Kolata and Wansink share a concern about the experiences of actual individuals, a welcome respite from the cold collectivism that characterizes most discussions of obesity. Kolata devotes much space to the struggles of particular dieters, while Wansink emphasizes that he is offering not a one-size-fits-all diet but a set of suggestions that readers who want to lose weight can use to put together plans that work best for them. Instead of asking what the government should do about our flab, these books leave us alone with our bathroom scales to weigh the question for ourselves.
Senior Editor Jacob Sullum is a nationally syndicated columnist.