Adolescent girls who engage in weight-loss efforts such as dieting, use of appetite suppressants and laxatives, and vomiting are more likely to gain weight over time and are at greater risk for the onset of obesity, according to a new study of 692 adolescent girls. The study by psychologist Eric Stice, Ph.D., of the University of Texas at Austin and researchers from Stanford University School of Medicine appears in the December issue of the Journal of Consulting and Clinical Psychology, published by the American Psychological Association (APA).

The study involved ninth grade female students from three northern California high schools who were told the study was designed to investigate student health beliefs and behaviors. The participants were evaluated for three years; the evaluations included self-report questionnaires and weight and height measurements. Results indicated that, controlling for initial body mass, those adolescents who reported elevated dieting and radical weight-loss efforts were more likely to gain weight than those who did not report these efforts.

Besides appetite suppressant/laxative use and vomiting as indicators of eventual weight gain, the researchers also found that exercise for weight-control purposes led to increased growth in relative weight. The study's authors say this surprising finding may be because exercise leads to the development of higher bone density or muscle mass.

The researchers say there are at least two possible reasons for the study's findings. First, the girls' weight-reduction efforts "may not reflect decreased caloric intake and increased exercise. These youths may perceive that they are dieting or exercising at therapeutic levels when in fact they are not." The second reason is that such weight-reduction efforts in teenagers may be a marker for a propensity to become obese. "Perhaps individuals with a family history of obesity have already initiated weight-control efforts because they are concerned that they will follow in the footsteps of their parents," said the authors. On the other hand, endorsement of radical weight-reduction efforts "may signal a steep weight-gain trajectory that preceded study entry and continued despite the use of weight-control efforts. Such a steep weight-gain trajectory may be driven by a tendency to overeat, which might motivate the individual to report elevated weight-control efforts." The researchers add that future research should look into these different possibilities.

An additional finding of the study indicates that initial binge eating leads to weight gain. Although this may seem an obvious consequence of binge eating, Dr. Stice says this is a novel finding. "It has long been accepted that obese individuals do not consume more food than non-obese individuals on the basis of self-report and observational data from numerous studies. However, this position has been challenged with the advent of blinded strategies to assess caloric intake." Dr. Stice says the present study suggests that when you reduce the potential for reporter bias by not relying solely on self-reports from individuals in the study (research indicates that obese people under-report caloric intake by about 30% to 35%), it is possible to find evidence that over-eating is a risk factor of subsequent weight gain.

12/06/99

The American Psychological Association (APA), in Washington, DC, is the largest scientific and professional organization representing psychology in the United States and is the world's largest association of psychologists. APA's membership includes more than 159,000 researchers, educators, clinicians, consultants and students. Through its divisions in 50 subfields of psychology and affiliations with 58 state, territorial and Canadian provincial associations, APA works to advance psychology as a science, as a profession and as a means of promoting human welfare.