A parent's weight may also play a role in adolescent weight gain

The prevalence of adolescent obesity has doubled over the last 30 years and can lead to serious medical problems, like high blood pressure, diabetes, cardiovascular disease and colorectal cancer.

According to a new study, certain weight-control behaviors may actually contribute more to weight problems than other behaviors. Furthermore, parents who are overweight may also contribute to their adolescent's future weight problem. These findings are reported on in the April issue of the Journal of Consulting and Clinical Psychology, published by the American Psychological Association (APA).

In this study, psychologist Eric Stice, Ph.D., of the University of Texas at Austin and co-authors found that 496 adolescent girls (11-15 year olds) who used radical weight-control, were depressed and had obese parents were more likely to become obese. On the other hand, the authors found that eating high fat foods, binge eating or infrequent exercise were not as much linked to predicting future obesity as one might expect.

But other weight-control behaviors, especially those that involved vomiting or laxative abuse, promoted weight gain more than weight loss, said Dr. Stice. These behaviors can lead to increased metabolic efficiency or alter the homeostatic processes. Erratic eating also promotes weight gain because a person does not get regular delivery of nutrients, said Stice, which can alter a person's physiological responses and disrupt a person's normal appetite pattern.

Depressive symptoms also contributed to weight gain among adolescent girls. Besides the reasons for overeating to comfort or distract one's self, this finding in the study also showed that lack of serotonin that is usually inherent in depression also leads individuals to consume excessive amounts of carbohydrate-rich foods in an effort to regulate his or her serotonin levels. These foods can lead to gaining weight if one is not careful.

Furthermore, an adolescent's perception of her parents' weight also predicted the likelihood of the adolescent gaining weight. Those adolescents who reported having an obese parent were more than four times at risk for becoming obese themselves versus their peers who reported not having obese parents. This was the case for both biological and non-biological parents giving evidence that it may be a combination of genetics and environmental factors that predict obesity.

Interestingly, the weight-control behaviors – elevated intake of high-fat foods, binge eating and lack of exercise – did not predict the onset of obesity, possibly because people tend not to report these behaviors very accurately, noted the authors. Furthermore, said Dr. Stice, "we know from tightly controlled experiments with humans and other animals that eating bad foods, eating sporadically and not exercising is associated with weight problems."

These results suggest that prevention efforts should target those adolescents with these particular high-risk behaviors to understand what is causing the rise in obesity and to hopefully facilitate the design of effective preventative programs to stop this public health epidemic, said Stice.