Why We Get Fat: And What to Do About It (6 page)

In the early 1990s, the National Institutes of Health set out to investigate a few critical issues of women’s health. The result was the Women’s Health Initiative (WHI), a collection of studies that would cost in the neighborhood of a billion dollars. Among the questions that the researchers hoped to answer was whether low-fat diets actually prevent heart disease or cancer, at least in women. So they enrolled nearly fifty thousand women in a trial, chose twenty thousand at random, and instructed them to eat a low-fat diet, rich in fruits, vegetables, and fiber. These women were given regular counseling to motivate them to stay on the diet.

One of the effects of this counseling, or maybe of the diet itself, is that the women also decided, consciously or unconsciously, to eat less. According to the WHI researchers, the women, on average, consumed 360 calories a day less on their diets than they did when they first agreed to participate. If we believe that obesity is caused by overeating, we might say that these women were “undereating” by 360 calories a day. They were eating almost 20 percent fewer calories than what public-health agencies tell us such women should be eating.

The result? After eight years of such undereating, these women lost an average of
two pounds
each. And their average waist circumference—a measure of abdominal fat—
increased
.
This suggests that whatever weight these women lost, if they did, was not fat but lean tissue—muscle.
^*

How is such a thing possible? If our weight is really determined by the difference between the calories we consume and the calories we expend, these women should have slimmed down significantly. A pound of fat contains roughly thirty-five hundred calories’ worth of energy. If these women were really undereating by 360 calories every day, they should have lost more than two pounds of fat (seven thousand calories’ worth) in the first three weeks, and more than thirty-six pounds in the first year.
^†
And these women had plenty of fat to lose. Almost half began the study obese; the great majority were at the very least overweight.

One possibility, of course, is that the researchers failed miserably at assessing how much these women ate. Maybe the women deceived the investigators and themselves as well. Maybe they didn’t undereat by 360 calories a day. “We have no idea what these women were really eating because, like most people when asked about their diet, they lied about it,” as Michael Pollan suggested in
The New York Times
.

Another possibility is that this reduction in calories, this multi-year exercise in undereating, just didn’t do what it was expected to do.

Of all the reasons to question the idea that overeating causes obesity, the most obvious has always been the fact that undereating doesn’t cure it.

Yes, it’s true: If you are stranded on a desert island and starved for months on end, you will waste away, whether you’re fat or thin to begin with. Even if you are just semi-starved, your fat will melt away, as will a good share of your muscle. Try the same prescription in the real world, though, and try to keep it up indefinitely—try to maintain the weight loss—and it works very rarely indeed, if at all.

This should come as no surprise. As I suggested earlier, with the assistance of Hilde Bruch’s wisdom and experience, most of us who are fat spend much of our lives
trying
to eat less. If it doesn’t work when the motivation is merely decades of the intense negative reinforcement that accompanies obesity—social ostracism, physical impairment, increased rate of disease—can we really expect it to work just because an authority figure in a white coat insists that we give it a try? The fat person who has never tried to undereat is a rare bird. If you’re still fat, as Bruch noted, that’s a good reason to assume that undereating failed to cure you of this particular affliction, even if it has some short-term success at treating the most conspicuous symptom—excess adiposity.

The very first time anyone published a review of the efficacy of undereating as a treatment for obesity—the psychologist Albert Stunkard and his colleague Mavis McLaren-Hume, in 1959—this was their conclusion. Nothing much has changed since. Stunkard said their study was motivated by what he called the “paradox” between his own failure to treat obese patients successfully at his New York Hospital clinic by restricting how much they eat and “the widespread assumption that such treatment was easy and effective.”

Stunkard and McLaren-Hume combed the medical literature and managed to find eight articles in which physicians reported on their success rates treating obese and overweight patients in their clinics. The results, said Stunkard, were “remarkably similar and remarkably poor.” Most of these clinics were prescribing diets that allowed only eight hundred or one thousand calories a day—maybe half what the WHI women said they were eating—and still only one in four patients ever lost as much as twenty pounds;
only one in twenty patients managed to lose as much as forty pounds. Stunkard also reported on his own experience prescribing “balanced diets” of eight hundred to fifteen hundred calories a day to a hundred obese patients in his own clinic: only twelve lost as much as twenty pounds, and only one lost forty pounds. “Two years after the end of treatment,” Stunkard wrote, “only two patients had maintained their weight loss.”
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The more recent assessments benefit from the use of computers and elaborate statistical analyses, but the results, as Stunkard might say, are still remarkably similar and remarkably poor. Prescribing low-calorie diets for obese and overweight patients, according to a 2007 review from Tufts University, leads, at best, to “modest weight losses” that are “transient”—that is, temporary. Typically, nine or ten pounds are lost in the first six months. After a year, much of what was lost has been regained.

The Tufts review was an analysis of all the relevant diet trials in the medical journals since 1980. The single largest such trial ever done yields the very same answer.
^†
The researchers were from Harvard and the Pennington Biomedical Research Center, which is in Baton Rouge, Louisiana, and is the most influential academic obesity-research institute in the United States. Together they enrolled more than eight hundred overweight and obese subjects and then randomly assigned them to eat one of four diets. These diets were marginally different in nutrient composition (proportions of protein, fat, and carbohydrates), but all were substantially the same in that the subjects were supposed to undereat by 750 calories a day, a significant amount. The subjects were also given “intensive behavioral counseling” to keep them on their diets, the kind of professional assistance that few of us
ever get when we try to lose weight. They were even given meal plans every two weeks to help them with the difficult chore of cooking tasty meals that were also sufficiently low in calories.

The subjects began the study, on average, fifty pounds overweight. They lost, on average, only nine pounds. And, once again, just as the Tufts review would have predicted, most of the nine pounds came off in the first six months, and most of the participants were gaining weight back after a year. No wonder obesity is so rarely cured. Eating less—that is, undereating—simply doesn’t work for more than a few months, if that.

This reality, however, hasn’t stopped the authorities from recommending the approach, which makes reading such recommendations an exercise in what psychologists call “cognitive dissonance,” the tension that results from trying to hold two incompatible beliefs simultaneously.

Take, for instance, the
Handbook of Obesity
, a 1998 textbook edited by three of the most prominent authorities in the field—George Bray, Claude Bouchard, and W. P. T. James. “Dietary therapy remains the cornerstone of treatment and the reduction of energy intake continues to be the basis of successful weight reduction programs,” the book says. But it then states, a few paragraphs later, that the results of such energy-reduced restricted diets “are known to be poor and not long-lasting.” So why is such an ineffective therapy the cornerstone of treatment? The
Handbook of Obesity
neglects to say.

The latest edition (2005) of
Joslin’s Diabetes Mellitus
, a highly respected textbook for physicians and researchers, is a more recent example of this cognitive dissonance. The chapter on obesity was written by Jeffrey Flier, an obesity researcher who is now dean of Harvard Medical School, and his wife and research colleague, Terry Maratos-Flier. The Fliers also describe “reduction of caloric intake” as “the cornerstone of any therapy for obesity.” But then they enumerate all the ways in which this cornerstone
fails. After examining approaches from the most subtle reductions in calories (eating, say, one hundred calories less each day with the hope of losing a pound every five weeks) to low-calorie diets of eight hundred to one thousand calories a day to very low-calorie diets (two hundred to six hundred calories) and even total starvation, they conclude that “none of these approaches has any proven merit.” Alas.

Until the 1970s, low-calorie diets were referred to in medical literature as “semi-starvation” diets. After all, what’s expected on these diets is that we eat half or even less of what we’d typically prefer to eat. But we can’t be expected to semi-starve ourselves for more than a few months, let alone indefinitely, which is what such diets implicitly require if we are to maintain whatever weight loss we may initially experience. Very low-calorie diets are known as “fasts” because they allow barely any food at all. Again, it’s hard to imagine fasting for more than a few weeks, maybe a month or two at best, and certainly we cannot keep it up forever once our excess fat is lost.

The two researchers who may have had the best track record in the world treating obesity in an academic setting were George Blackburn and Bruce Bistrian of Harvard Medical School. In the 1970s, they began treating obese patients with a six-hundred-calorie-a-day diet of only lean meat, fish, and fowl. They treated thousands of patients, said Bistrian. Half of them lost more than forty pounds. “This is an extraordinarily effective and safe way to get large amounts of weight loss,” Bistrian said. But then Bistrian and Blackburn gave up on the therapy, because they didn’t know what to tell their patients to do after the weight was lost. The patients couldn’t be expected to live on six hundred calories a day forever, and if they returned to eating normally, they’d gain the weight right back. The only medically acceptable alternative, said Bistrian, was to give the patients drugs to kill their appetites, and they weren’t willing to do that.

So, even if you lose most of your excess fat on one of these diets, you’re then stuck with the what-happens-now problem. If you lose weight eating only six hundred calories a day, or even twelve hundred, should it come as a surprise that you get fat again when you return to eating two thousand calories a day or more? This is why the experts say a diet has to be something we can follow for life—a lifestyle program. But how is it possible to semi-starve ourselves or fast for more than a short time? As Bistrian said when I interviewed him a few years ago, echoing Bruch half a century earlier, undereating isn’t a treatment or cure for obesity; it’s a way of temporarily reducing the most obvious symptom. And if undereating isn’t a treatment or a cure, this certainly suggests that overeating is not a cause.

Imagine you’re invited to a celebratory dinner. The chef’s talent is legendary, and the invitation says that this particular dinner is going to be a feast of monumental proportions. Bring your appetite, you’re told—come hungry. How would you do it?

You might try to eat less over the course of the day—maybe even skip lunch, or breakfast and lunch. You might go to the gym for a particularly vigorous workout, or go for a longer run or swim than usual, to work up an appetite. You might even decide to walk to the dinner, rather than drive, for the same reason.

Now let’s think about this for a moment. The instructions that we’re constantly being given to lose weight—eat less (decrease the calories we take in) and exercise more (increase the calories we expend)—are the very same things we’ll do if our purpose is to make ourselves hungry, to build up an appetite, to eat more. Now the existence of an obesity epidemic coincident with half a century of advice to eat less and exercise more begins to look less paradoxical.
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We’ve seen the problems with eating less to produce weight loss. Now let’s examine the flip side of the calories-in/calories-out equation. What happens when we increase our energy expenditure by upping our level of physical activity?

It’s now commonly believed that sedentary behavior is as much a cause of our weight problems as how much we eat. And because the likelihood that we’ll get heart disease, diabetes, and cancer increases the fatter we become, the supposedly sedentary nature of our lives is now considered a causal factor in these diseases as well. Regular exercise is now seen as an essential means of prevention for all the chronic ailments of our day (except, of course, those of joints and muscles that are caused by excessive exercise).