By Duke Medicine News and Communications

A recent study found that teenage girls who used severe methods to lose weight were more likely to become obese than girls who ate a high-fat diet. A Duke expert says radical weight-loss measures change the body's metabolism and actually promote weight gain.

Adolescent girls who try to lose weight by extreme measures such as vomiting, laxative abuse and skipping meals are actually more likely to become obese than girls who eat a high-fat diet.

The finding, part of a four-year study of almost 500 teenage girls in Austin, Texas, was published in the April 2005 issue of the American Psychological Association's Journal of Consulting and Clinical Psychology.

Dr. Terrill Bravender, medical director of the Duke Eating Disorders Program, says the study results shouldn't come as a surprise.

"Although this seems counter-intuitive, it actually makes quite a bit of sense," he explains. "We know from other research that skipping meals sets you up for eating more food throughout the rest of the day. Appetite increases dramatically and satiety control decreases. It's almost like the body goes into starvation mode in those instances and actually over-compensates for the lost energy that it's experiencing.

"Adolescents or even adults who fast for prolonged periods of time or severely restrict their caloric intake are more likely to binge-eat to compensate for that lack of food intake, either earlier in the day or in days prior."

In effect, says Bravender, employing severe methods to lose weight is likely to have the opposite result. "As with any attempt at controlling weight and managing health, moderation is the key. Episodes of starvation or extreme weight loss-control most likely lead to subsequent binge eating, which negates all the work you've done with those extreme weight-loss measures. The best approach is moderation in eating, eating a well-balanced, healthy diet, limiting snacking and getting a modest amount of daily physical activity."

Bravender, director of adolescent medicine at Duke, notes that there are many other factors that contribute to an increased risk for obesity in children and teens. One of these factors is parental obesity; another is parental attitudes toward food.

"I think this an example where parental modeling of good behavior is incredibly important. We know that obesity tends to run in families for a variety of reasons. Genetics is one reason, but even in adoptive families we see a higher likelihood of children being obese if their adoptive parents are also obese. I think that has a lot to do with modeling around food.

"This includes not just the types of foods that are available in the home, but also eating styles, for example decreasing snacking and making sure to eat at proper mealtimes. Parental attitudes toward food also have a huge influence on children. If parents see some foods as a reward, or see some foods as 'good' and others as 'bad,' children will internalize that message and develop those same attitudes about food.

"There's a study from a number of years ago looking at 9- and 10-year-old girls. Over 40 percent of those girls said that they either were on or had been on a diet to lose weight. Those 9- and 10-year-olds didn't come up with that on their own. I'm sure they're imitating their parents."