Parents of overweight teens would do well to think twice before suggesting their son or daughter go on a diet, according to a new study.

Being encouraged to diet roughly tripled a boy or girl's likelihood of still being overweight 5 years later.

Pointing out your child's weight problem directly and suggesting a diet is likely to make your child criticized, according to Dr. Dianne Neumark-Sztainer of the University of Minnesota, Minneapolis and her colleagues.

Better than talk is for parents to take action. Buy more vegetables; turn off the TV; take a walk or find other ways to be more active as a family; have more meals together. Don't nag about dessert and second-helpings. Make them lower calorie.

The study of 170 parent-overweight child pairs began by looking at how accurate parents were at determining if their teenager was overweight.

Only slightly more than half of the parents of overweight girls — 54% — accurately classified their daughters as overweight. The parents of boys were even less accurate. Only 40% of these parents recognized their sons' weight problems.

But it was the parents who recognized their teen's weight problem who were the problem. Even though 57% of them said they encouraged their teen to control their weight, they were just as unlikely as parents in the study who were unaware of their child's weight problem to take steps to improve their overweight child's activity level and eating habits. They continued to serve higher fat, higher calorie meals and to have soft drinks, snacks and candy in the house.

Kids of parents who talked about diet but did little to help change household eating habits were far more likely to become obese over the next five years than were teens whose parents didn't see, and therefore didn't discuss, the weight problem.

The reason for this, according to Neumark-Sztainer is that kids focused on dieting are likely to binge and skip breakfast which other studies have shown is a recipe for weight gain.

In addition, teens whose parents who focused only on dieting as a route to weight loss were unlikely to consider other, more effective weight-loss strategies — like exercising more or eating more vegetables and less fat.

The study was published in the June issue of the journal, Pediatrics.