What they found was that vegetarians, on the whole, tended to eat a healthier diet and be at a healthier weight than their meat-eating counterparts. But they also found that those who reported either currently being vegetarian or having been at some point in the past were also more likely to report engaging in more unhealthy weight control behaviors -- including binge eating, taking diet pills, inducing vomiting or using laxatives.
"Parents should know that vegetarianism can be a healthful dietary option for teens," when done properly, said lead study researcher Ramona Robinson-O'Brien of the College of Saint Benedict and Saint John's University in Minnesota.
But, she said, "Parents should talk to their child about their motivations for embarking on a vegetarian diet. If reasons are primarily related to weight loss, parents should explore this topic in more depth to further assess an increased risk of disordered eating behaviors."
Eating disorders specialist Dr. David Waller, a clinical professor of psychiatry at the University of Texas Southwestern Medical Center at Dallas, agreed that teens with eating disorders may try to use their supposed vegetarianism as a convenient excuse to eat less.
"What we would be concerned about ... might be that in some instances a [claim of a] vegetarian diet could conceal an underlying decision to lose weight and restrict food intake," he said. "This might be, for some teenagers, a more acceptable way of restricting their eating rather than being more overt or explicit about it."
Should Parents Support Teens' Vegetarianism?
Dr. Neal Barnard, founder and president of the Physicians Committee for Responsible Medicine and a staunch supporter of a vegetarian diet, acknowledged that some young people may adopt this strategy. But he also emphasized that parents must be careful not to dissuade their children if they choose to be vegetarian.
"When a child decides to become a vegetarian ... it is something to be welcomed," he said. "This is not a reason for worry; it is a reason for parents to be happy -- that child has just cut his or her risk of being overweight or having heart disease."
Vegetarian Means Healthy -- Most of the Time
Studies on adult vegetarians support the notion that such a lifestyle choice is a healthy one. Past research has shown that people who have cut meat from their diet have a lower risk of certain metabolic disorders, including diabetes. And this new research appears to reinforce at least some of these findings in a younger population.
"What this study indicates is that a vegetarian diet has benefits in terms of a person being less likely to develop obesity and the consequences of that -- that's good news," Waller said. "There are certainly benefits to a vegetarian diet."
But as American Dietetic Association spokeswoman Keri Gans noted, vegetarianism must be done right to reap the benefits.
"Just like with any way of eating, you still need to be concerned with certain issues," she said. "Even if it is a vegetarian diet, it does not necessarily mean it is a healthy diet."
Specifically, vegetarians must find sources other than meat for protein. Those who opt to go vegan must be even more vigilant when it comes to finding substitutes for other nutrients, such as the calcium that they might otherwise get from dairy products.
But with unhealthy eating behaviors, restrictive eating goes even a step further. If teens are motivated more by weight than by health, they may end up cutting back their calories to dangerous levels -- or bingeing and purging.
Barnard contended, though, that the fact that the study was based on self-report -- that is, answers that the young subjects provided themselves -- suggests that perhaps some of these kids did not understand what it meant to be vegetarian.
Indeed, researchers in the study found that among those who identified themselves as vegetarian, 46 percent said they still ate fish and more than 25 percent said they ate chicken. In this light, he said, it was more likely that some teens simply used vegetarianism as a cover for their unhealthy eating habits.
What Parents Can Do
With this in mind, parental involvement in teens' diets may be even more important than parents realize.
"Parents should try to help their teens," Gans said. "The best thing that parents can do is work with their teens to help them create a healthy meal plan. If they are confused, they should consult a dietitian."
Barnard said that parents should make an effort to spend time with their teens at mealtime to ensure that they are eating a healthy diet.
"When parents eat with their children, that helps -- they actually can see what their children are eating," he said. "If they are with them after the meal, as well, they are going to know if they duck out and vomit."
"Having said that, kids can hide these things."
Waller noted that it may even be a good idea to get doctors involved -- particularly if parents are concerned that their child may indeed be hiding an eating disorder behind a vegetarian label.
"It is important to have some ongoing meetings at the pediatrician's office just to see that this person is not losing control of normal eating behaviors," he said.