While Washington policymakers debate how best to stem the obesity epidemic across the nation, many of us are struggling with how to deal with the obesity epidemic in our own homes. A third of all youngsters are now overweight or obese, well on their way to joining the two thirds of adults whose weight also tips the scales at unhealthy levels. Potential solutions are at least as controversial in America's kitchens as the single-payer plan is on Capitol Hill. Should we ration chips and soda? Or kick the kids outdoors so they get at least a minimum level of physical activity every day? Do we clear the pantry of junk food? Or all of the above?
Now a new study by researchers at the University of Buffalo suggests an even more radical idea: banning fat friends from eating together. Sarah-Jeanne Salvy, an assistant professor of pediatrics at the university's School of Medicine and Biomedical Sciences, and her colleagues found that fat kids consume significantly more calories when they chow down with friends who are also overweight than when they eat with lean friends.
In the study, published in the August issue of The American Journal of Clinical Nutrition, researchers randomly paired 23 overweight and 42 normal-weight children between the ages of 9 and 15 with either a friend or a kid they did not know. There were 33 friend pairs and 39 stranger pairs. Each pair of kids spent 45 minutes in a room that contained puzzles, games, and bowls of both healthy snacks (in this case, baby carrots and grapes) and calorie-rich treats (potato chips and cookies). The kids could eat as much as they wanted, but only from their own bowls. The researchers monitored the youngsters on closed-circuit TV. Afterward they weighed the uneaten snacks to figure out how many calories the kids had consumed.
The results showed that in general, friends who ate together took in more calories than youngsters who were unfamiliar with their partner. That was true for both fat and thin kids. Not surprisingly, overweight kids ate more than lean kids, whether or not they were paired with a friend. And they ate even more when they were paired with another overweight youngster. The greatest number of calories was consumed by two overweight friends eating together in what Salvy describes as a kind of synergistic effect. "Being friends increased food intake, being overweight and eating with an overweight [person] increased eating, and when you combined those, the overweight friends were eating about 700 calories," Salvy says. (The lean kids consumed several hundred fewer calories.) And, she points out, this is snack food—which means they were consuming a good chunk of their daily calories in that one sitting.
The effect of friends on food intake is an increasingly interesting subject to researchers. In 2007, a highly publicized study in The New England Journal of Medicine found that when a person becomes obese, his or her friends increase their own risk of obesity by 57 percent. The greatest influence was among close friends. If one became obese, another had a 171 percent increased chance of also becoming obese. This epidemiological study, which used data over a 32-year span, made the growth of obesity seem like a virus spreading among social circles—a finding that Salvy thinks is not far off the mark. But, she says, the contagion is spread not by an infecting organism but by a form of social conditioning. As Americans get fatter, our ideas of what is a normal body size can become distorted, she says. "I don't think people see others as being overweight anymore," she says. "If anything, they see people who are normal weight as being overly skinny."
Some extra pounds may have become the norm, but there is also a growing stigma against the obese. And that complicates the whole question of how to apply Salvy's research. The New England Journal study showed that overweight adults were a negative influence on their friends over a period of many years, but that doesn't necessarily mean that fat kids will make thin kids eat more than they should. In fact, Salvy thinks that a normal-weight child is more likely to be a positive influence on a fat youngster than the other way around. "The overweight kid who eats with the lean kid is going to eat less," she says, because such kids are aware of the stigma against obesity and "they are becoming more self-conscious. They don't want to be seen as a pig."
But what about two fat kids? Should they stay away from each other just as recovering alcoholics tend to stay away from drinkers? No, says Salvy—basically because overweight youngsters have enough social problems without adding ostracism to the list. A fat child "might have only a few friends, so I don't want to isolate those kids," she says. And research shows that isolation could exacerbate their bad eating habits. "We do have some data showing that overweight kids … eat more when they are alone than when they are with other people," she says (that's also true for women). Instead, Salvy advises parents to focus on the dynamic between the friends by helping their child be a good example for the other youngster. Serve healthy meals at home, and encourage your youngster to become more physically active. But be positive; nagging won't help. "If one of the kids starts changing," she says, "chances are the other kid is going to model those behaviors."
None of this is easy, of course. Getting kids to eat right and exercise is at least as complicated as finding the solution to the health-care crisis in Washington. Salvy is now studying how parents affect their youngsters' eating behavior. Carrots, anyone?