If adolescent girls purge in one way or another to control weight, they’re likely to gain more pounds than they lose, according to new study findings.

Dr. Eric Stice of the University of Texas at Austin and his colleagues found that teenaged girls who said they abused laxatives or forced themselves to vomit in order to lose weight were more likely than other girls to become obese.

In an interview, Stice explained that these practices don’t make a significant dent in caloric intake, and may also slow down dieters’ metabolism, making it harder for them to lose weight.

Furthermore, people who are more prone to overeating may be more likely to try drastic measures like vomiting and laxatives to cut back, he noted.

Extreme dieting measures are “ultimately ineffective, and the overeating wins out,” Stice told Reuters Health.

The best way to prevent Obesity is much more straightforward, he said: permanently and consistently avoid eating more calories than you use. “Look at your diet and activity level, and make the changes you need to make,” he recommended.

To investigate whether some dieting strategies might backfire for young girls, the researchers asked 496 girls between the ages of 11 and 15 about their eating habits, then checked in with them annually for the next 4 years.

They found that girls who resorted to laxatives and vomiting were five times more likely to become obese during the study period.

Eating erratically, being depressed and having an obese parent also appeared to put girls at risk of gaining weight, Stice and his colleagues report in the Journal of Consulting and Clinical Psychology.

Stice explained that other studies have also found that depression can trigger obesity, likely because people turn to food to make themselves feel better. Having an obese parent can be dangerous because household refrigerators are likely to be filled with unhealthy food, and young girls receive bad examples of what to eat at meals, he noted.

Surprisingly, eating high-fat foods, binge eating and exercising infrequently did not appear to increase young girls’ risk of becoming obese - but that doesn’t mean those behaviors are harmless, he said.

The most likely reason why obesity appeared unaffected by those behaviors is that people were not always honest about how often they eat fatty foods, binge eat and exercise, Stice speculated.

“People know what they should say, instead of what they’re actually doing,” he commented.

SOURCE: Journal of Consulting and Clinical Psychology, April 2005.