If your child wants to give up meat, help him or her to make the healthiest food choices.

Teens don't always choose a vegetarian diet for healthy reasons.

RODALE NEWS, EMMAUS, PA—Teenagers may be the very greenest among us. According to a recent survey from Greenpeace and the online teen hangout, Habbo.com, 74 percent of American teenagers are concerned about environmental issues like global warming and pollution, while a recent Harris Interactive poll found that only 46 percent of adults feel the same way.

But the way these eco-teens are going about protecting our planet may be putting their own bodies at risk. A recent study published in the Journal of the American Dietetic Association found that teenage vegetarians, most of whom said they chose their diet for its environmental benefits, were more likely to develop eating disorders than their meat-eating peers.

THE DETAILS: The study was based on survey data collected from 2,516 men and women divided into two age groups, a younger group (15 to 18 years old) and an older group (19 to 23 years old). They were asked questions based on whether they ate meat and, if not, why they chose to become vegetarians. Participants also reported on their “weight control behaviors.” Healthy behaviors for weight control were defined as exercising, eating more fruits and vegetables, and avoiding fatty foods and sweets; unhealthy behaviors were categorized as either less-extreme (fasting, skipping meals, eating food substitutes, smoking more cigarettes) and more-extreme (binge eating, taking diet pills or laxatives, making yourself vomit).

The most popular reason for giving up meat in the younger group was to help the environment, while the older vegetarians did so because they wanted to eat a healthier diet. However, among the younger age group, 21 percent of vegetarians reported engaging in uncontrollable binge eating and 20 percent in other more-extreme weight control behaviors, compared with 4 percent and 10 percent, respectively, for non-vegetarians.

WHAT IT MEANS: “Vegetarian” doesn’t automatically equal “healthy,” especially for a teen who doesn’t have a healthy relationship with food. The study authors point out that it’s important for parents to make sure their children aren’t using a vegetarian diet as a socially acceptable excuse for hiding an eating disorder. The key is to get involved and make certain that a child who chooses to forgo meat is eating a healthy diet. Being supportive of a teenager who decides to give up meat can also lead to other healthy behaviors, the study found. “Both the vegetarian adolescents and young adults reported the highest fruit and vegetable intake and lowest percentage of total calories from fat,” says lead author Ramona Robinson-O’Brien, Ph.D., RD, assistant professor in the Nutrition Department of Saint Benedict and St. John’s University. They also found that vegetarian teens got more exercise and were less likely to smoke, drink alcohol, or take other drugs than their formerly vegetarian and non-vegetarian peers.

Here are a few ways to keep your teenager on a healthy track with a vegetarian diet: