Tell teens to diet? Fat chance that works

If you want your overweight teenagers to slim down, don't tell them to go on a diet. That most likely will make matters worse, according to a new study.

University of Minnesota researchers who study adolescent health found that parents who correctly perceived their kids as overweight tended to use only one strategy: advising them to diet. But five years later, those kids were far more likely to still be too heavy than were overweight kids whose parents had no idea they were fat and did nothing.

In short, it's a technique that seems certain to backfire, said Dianne Neumark-Sztainer, a professor of epidemiology at the university and the lead author of the study published this week in the journal Pediatrics.

"My concern is that if parents know their kids are overweight, they are going to do things that lead to further weight gain over time," she said.

Neumark-Sztainer said she decided to research the issue because of the growing practice of schools evaluating kids' weight and sending the results home to parents. In some places it's called an obesity report card. It began because parents often don't know whether their kids are at a healthy weight, and some experts think telling them is one way to fight skyrocketing rates of childhood obesity.

The practice was recommended for schools by the federal government's health advisory agency, the Institute of Medicine. But it's highly controversial because it can be embarrassing and stigmatizing to adolescents and teenagers.

"When my son became overweight in middle school, they used to measure body fat and send (the result) home with him," said Anne Fletcher, a Mankato, Minn., mother and the author of "Weight Loss Confidential," a book that examines how teenagers, including her own son, successfully lost weight. "It was devastating. He said, 'Don't they know I already know I'm fat?' "
Neumark-Sztainer said she wanted to find out whether parents would use that information wisely.

The researchers looked at survey results for 300 adolescents and some of their parents taken in 1998 as part of an ongoing adolescent health study at the university called Project EAT. The kids, from Minnesota middle and high schools, reported heights and weights that put them in the overweight category.

They found that 46 percent of girls' parents and 60 percent of boys' parents incorrectly thought their kids' weights were about right. Of the parents who knew their kids were too heavy, about 60 percent encouraged them to diet.

In 2003, about 200 of the kids were re-surveyed. Those who had been encouraged to diet were much more likely to still be overweight -- about 74 percent of boys compared with 52 percent of those boys not encouraged to diet. For girls, the difference was 66 and 44 percent, respectively. Both groups reported about the same eating patterns, including the frequency of fast-food meals, and the quantity of fruits and vegetables at home.

Neumark-Sztainer said public health experts have known that adolescents and teenagers who say they diet are the ones who are most likely to have long-lasting weight and eating disorder problems. She said this study shows that just informing parents their kids are overweight is counterproductive.

"If you are going to talk with parents about their children's weight, you need to specifically help them make positive changes at home," said Neumark-Sztainer, who has written a book for parents on the subject called "I'm Like So Fat."

Fletcher said that when she talked to teens for her book, they said the worst thing their parents could do was pressure them.

"Nagging, preaching, coercion does not work," she said. "Let the kid be in charge. It's up to the teen to decide if and how he or she wants to lose weight."

That can be very difficult for parents. "There seems to be a fine line between helpful and harmful parenting," the researchers said in their study.

The best thing parents can do to be role models, said Neumark-Sztainer, is to provide and eat healthful food, have regular family meals, and do physically active things with their kids. "Do more. Talk less," she said.