Trying to teach adults how to lose weight is about as effective as teaching house cats to swim. For most people, diets simply don't work. The latest evidence: a recent study published in the New England Journal of Medicine examining diets with different proportions of carbohydrates, protein, and fat. Not surprisingly, it made no difference what kind of diet people followed; if they reduced calories, they initially lost weight. But after two years, average participants had regained weight, leaving them with a net loss of just 9 pounds . . . and on a path toward further regain. A similar study published in 2007 also found that dieters regained weight regardless of their regime.
Certainly, a small portion of dieters do manage to keep weight off; about 15 percent of participants in the latest NEJM study dropped at least 10 percent of their body weight. There may be things to be learned from looking at how they differ from their less successful study participants-perhaps they simply have better willpower or more time to come to counseling sessions. But in looking for a broad-based, cost-effective solution to the problem of obesity, some wonder whether the field needs a major attitude change.
"[It's a] basic instinct, even stronger than the sexual instinct, to store calories to survive the next period of starvation, says Martijn Katan, of the Institute of Health Sciences at VU University in Amsterdam, who wrote an editorial that appeared in NEJM along with the most recent diet study. "And we live in an environment where there's food every half mile. It's tasty, cheap, convenient, and you can eat it with one hand," he says. Against that background, he argues, individual treatment, whether focusing on dietary components or behavior, is most often futile.
He and others, including obesity researcher Barry Popkin, urge that more research dollars be directed toward studying community-based efforts that tackle the problem from multiple angles: Towns might build more bike paths and playgrounds, students might get more physical education in schools, nutritionally vacant foods might be taxed to discourage consumption, families might have access to free counseling. The point isn't that any one of these measures has been so proved to work that it should be rolled out nationwide but that these components need to be studied. "What really works, if you look at it in a cold, scientific way?" wonders Katan.
There's been some preliminary research suggesting that broad, community-based efforts may help. One program, in two small towns in France, was described this way by Katan in his editorial: "Everyone from the mayor to shop owners, schoolteachers, doctors, pharmacists, caterers, restaurant owners, sports associations, the media, scientists, and various branches of town government joined in an effort to encourage children to eat better and move around more." Inspired by some evidence that it works to curb the prevalence of overweight and improve the health of adults as well, a larger program called EPODE is now being rolled out in France and elsewhere in Europe. While EPODE is promising, more research is needed to see whether such a community approach works and how it might be implemented outside Europe.
That's especially true in the United States, where the individualistic culture is supportive of the idea that obesity is more a matter of personal responsibility and less one that requires regulation of industry and other large policy changes. "It's great for people to be responsible, but we have to make it easy for them," says Marlene Schwartz, deputy director for the Rudd Center for Food Policy and Obesity at Yale University. "We have to create an environment that facilitates responsibility." She says that after training as a clinical psychologist and studying therapeutic techniques for treating eating disorders such as binge eating disorder, she came to believe that "a very small percent of the obesity problem is due to emotional distress and that the largest contributor is the environment. So I've shifted my research more towards policy change."