Pushing diets probably won't help. Neither will teasing about weight. Instead, parents should focus on having frequent family meals, creating a positive atmosphere at mealtimes, promoting physical activity and building self-esteem, the researchers recommend.

The study of more than 2,500 adolescents over five years reinforced several things that doctors have found among their patients -- particularly that destructive behaviors such as vomiting or abusing laxatives are prevalent among overweight teens as well as their too-thin peers, and that body attitudes and perceptions can play a big role in future weight problems.

"This is obviously of concern," Dianne Neumark-Sztainer, lead author of the study at the University of Minnesota, said of the risky behaviors. "We know that these behaviors tend to actually increase weight gain over time."

The research will be published in the November issue of American Journal of Preventive Medicine.

The study found that 44 percent of the girls and 20 percent of the boys were either overweight, engaged in binge eating or had used extreme weight-control measures -- such as purging or abusing laxatives, diet pills or diuretics.

Of the overweight teens, about 25 percent of the girls reported using extreme measures.

The medical director of the Eating Disorder Center of Denver, Dr. Carolyn Ross, said she was interested in the way the study linked teasing and pressure to lose weight to an increased risk in obesity and binge eating five years later.