Obesity and eating disorders in teens spring from some of the same causes
When Kendrin Sonneville was on a fellowship in adolescent nutrition at Children’s Hospital Boston, she met with teenagers, mostly girls, who were either obese or struggling with eating disorders such as anorexia or bulimia. Polar opposites, right? The obsessive, would-be fashion models who chew ice as a meal, and the extremely overweight girls who don’t put enough effort into taking care of themselves.
But that’s not what Sonneville, N02, saw. “I felt there were more similarities in the work I did with those patient populations than there were differences,” she says. She found that eating disorders and obesity can happen in the same person, as is the case with binge eating disorder. And although anorexia may appear the antithesis of obesity, the two often spring from some of the same causes.
Topping the risk factors for both is dieting. You would expect dieting to be exactly what we want overweight people to do. But when children diet—and nearly 56 percent of girls and 39 percent of boys ages 6 to 11 report they do—it usually backfires. In one three-year study of 15,000 adolescents conducted by Sonneville’s colleagues at Children’s Hospital, those who said they were dieting gained more weight than their non-dieting peers.
Why the weight gain? Their metabolisms may slow down if they drastically cut calories. But the simpler explanation, one Sonneville has seen in action, is that when kids diet, it is not the kind of healthy eating dietitians espouse, such as swapping out potato chips for apple slices.
Rather, they skip meals and fast—risky behaviors that lead to such overwhelming hunger that they lose all restraint and then binge eat. Or they might think a pack of Twizzlers makes a low-calorie dinner—even though these nonfilling, quickly digested foods lead to more hunger. Then there are extreme dieting behaviors, such as taking laxatives and diet pills as well as vomiting after a meal.
Setting Kids Up for Trouble
“Dieting is a slippery slope,” says Sonneville, now director of the adolescent nutrition fellowship at Children’s, where she primarily conducts research but still sees patients as a clinical nutritionist. “Virtually every case of an eating disorder starts with dieting,” she says. “There is a type of dieting that is really pathological and dangerous and leads to the eating disorder track, and then there is the dieting done wrong that leads to the obesity track.”
Despite their commonalities, obesity and eating disorders are usually dealt with from opposite directions: Most obesity research is focused on prevention, particularly in childhood, while eating disorders are addressed through expensive and only moderately successful medical and psychiatric treatment when—and if—they are diagnosed.
“It really seems like eating disorders don’t exist in the public health arena the way that obesity does,” Sonneville says. “Prevention of eating disorders is really a kind of novel concept, whereas obesity prevention is something we hear about a lot.”
Sonneville, who also has a Ph.D. from the Harvard School of Public Health, makes the case that our attempts to curb childhood obesity—from Body Mass Index report cards sent home by schools to the recent public health ad campaign in Atlanta that features slogans such as “being fat takes the fun out of being a kid”—should also target eating disorders.
She isn’t arguing that current obesity interventions are setting kids up for trouble with anorexia or binge eating. But with all the effort being put into child obesity prevention, Sonneville sees a lot that could be done simultaneously to prevent eating disorders—by keeping public health messages focused on healthy eating and feeling good, rather than making kids and parents feel guilty.
“We want to make sure all of our obesity prevention is not doing more harm than good, that we are collecting data on adverse consequences,” she says. “But we should also know that we can actually help them both at the same time,” she says. “If a single intervention can kill more than one bird, it’s a good use of public health time and dollars.”
Weighing the Stats
Eighteen percent of American adolescents are considered obese, more than triple the rate reported in the mid-1970s. Compared to such epidemic proportions, eating disorders may seem like a small matter. It’s true that anexoria, which is self-starvation, and bulimia, which is purging by vomiting or exercising excessively after eating, are pretty rare, affecting about 1 percent of adolescents. Binge eating disorder, or the frequent consumption of huge quantities of food, is more common, affecting up to 2.3 percent of adolescent girls.
Yet these are diagnosed cases, and the criteria are pretty specific. (According to upcoming guidelines by the American Psychiatric Association, for a person to be diagnosed with binge eating disorder, she would have to gorge herself, while feeling shame and a loss of control, at least once a week for three months.)
But add in cases that don’t fit the clinical definitions, including people who purge after eating but still maintain a normal weight, and those who chew their food and then spit it out, and Sonneville estimates, based on her recent analysis, that 20 percent of adolescent girls exhibit disordered eating habits at some point—a percentage that rivals the prevalence of obesity.
“For something like obesity or blood pressure, it’s not a dichotomous outcome,” she says. “In the same way, it’s not like ‘eating disorder’ or ‘no eating disorder.’ You fall somewhere on the continuum, and the goal of public health is to shift the distribution down.”
Historically, eating disorder researchers and obesity experts have not worked together, in part because eating disorders are considered mental illnesses, so a lot of the research lives in psychology journals. Obesity research tends to be published in biomedical journals. Only in the last decade have researchers in both fields proposed joining forces.
“It may seem that we are working at opposite ends of the spectrum, but in fact, there are lots of empirical and theoretical arguments for integrating the two, particularly integrating the prevention of the two,” Sonneville says.
Look in the Mirror
That means counteracting the shared risk factors. In addition to dieting, researchers have found a number of things that can set kids on the road to obesity, eating disorders or both, including exposure to media promoting the thin-is-beautiful ideal, being teased about their weight by other kids or even family members, and being dissatisfied with their bodies.
It might seem that body dissatisfaction would be a result, not a cause, of obesity. But about half of girls, including normal-weight girls, report some degree of unhappiness with their bodies. That dissatisfaction, some studies have suggested, could lead to dieting, binge eating and weight gain.
At the same time, some researchers believe that for overweight people, dissatisfaction is key to losing weight. Sonneville tells of one dietitian she worked with who would tell her overweight patients that if they wanted to eat a high-calorie food, they should take off their clothes, look in a mirror and then decide if they really wanted to eat it.
“She is actually a very smart clinician, and her thinking was that this body dissatisfaction is going to motivate her patients to change,” Sonneville says. “I think her intentions were good, but it’s not an uncommon thought among clinicians that if you are happy with yourself, you are not likely to change your body.”
So could some measure of unhappiness be a good thing? Should public health campaigns try to point out that a fat person is an unhappy person? For teens, Sonneville would argue no.
For her paper in the International Journal of Obesity, she tracked 1,500 overweight and obese girls (starting at about age 12) for 11 years. During that time, the girls who reported being at least somewhat satisfied with their bodies gained less weight than the girls who were dissatisfied. “All the overweight kids in the [study] are gaining weight, but those who are the most satisfied with their bodies are gaining less,” Sonneville says.
Perhaps more telling is how body satisfaction affected eating disorders. Although none of the girls had an eating disorder at the start of the study, by the end, 9.5 percent of them met the criteria for binge eating disorder at least once. Yet the girls who were at least somewhat satisfied with their bodies were 60 percent less likely to develop such a disorder. In fact, among girls who were totally satisfied with their bodies, Sonneville did not see a single incidence of binge eating disorder.
“With overweight, obesity and eating disorders, I think the goal is to find out what are safe messages across the board. And that is, in part, what we did in this study,” Sonneville says. Whether the message is coming from parents, teachers or a poster in gym class, “we know that if you are teaching kids to like their bodies, it is not harming them. If you have a kid who is overweight, and are sending messages about ‘you are great the way you are’ and ‘you should love your body,’ that may not be a bad thing.”
First, Do No Harm
Keeping obesity interventions from triggering eating disorders may be as simple as asking the right questions. She points to some obesity prevention efforts, such as an after-school dance program developed by Stanford University for low-income African-American girls, that track kids’ weight but also monitor whether they develop eating disorders, to ensure they aren’t accidently nudging them down the wrong path.
“[That] concern is real, and I think it is important that the unintended consequences of well-intentioned public health works are not overlooked,” says Aviva Must, N87, N92, the Madoff Professor and Chair of Public Health and Community Medicine at Tufts School of Medicine. “The kind of work that [Sonneville] has done is really important in terms of keeping that front and center in policymakers’ eyes.”
Figuring out exactly what a public health campaign for obesity/eating disorder prevention might look like is an area wide open for research, Sonneville says.
Sonneville and Must each have done research into the efficacy of BMI screenings, something a growing number of public schools are doing. In a 2008 study that Must conducted in the Cambridge, Mass., public schools, she found that overall, middle schoolers were not bothered about having their weight checked at school, although, perhaps not surprisingly, overweight and obese girls felt the most uncomfortable about it.
But when students reported what they would do with their BMI information, the overweight and obese girls were more likely to say that they intended to try some risky weight-control behaviors, such as fasting.
Must says the screenings seem to have value and reflect society’s concern “that we have a very large public health problem and we need to face it directly.” But sending home BMI report cards isn’t enough. School health workers need to reach out to parents about how to talk to their child’s health-care provider and what community resources are available.
“The BMI reports could be the launch pad for some useful conversations,” Must says. “And I think talking about body image, self-esteem and disordered eating as part of that conversation is advisable.”
But if a teen’s dissatisfaction with her appearance isn’t a good motivator, what is? What should we say to kids to prevent them from becoming overweight?
Perhaps, Sonneville says, parents, teachers and doctors don’t need to talk about weight at all. Children may be better served by creating an environment where healthy foods are the default option, physical activity is never a punishment but always done for pleasure and adults model healthy behaviors and don’t ridicule their own bodies or those of others.
This article first appeared in the summer 2012 issue of Tufts Nutrition magazine.
Julie Flaherty can be reached at firstname.lastname@example.org.