Weight-control behaviors and subsequent weight change among adolescents and young adult females.

BACKGROUND Little is known about the effectiveness of behavioral strategies to prevent long-term weight gain among adolescents and young adults. OBJECTIVE The objective was to assess the relation of dietary and physical activity weight-control strategies, alone and together, with subsequent weight change. DESIGN This was a prospective study of 4456 female adolescents and young adults aged 14-22 y in the ongoing Growing Up Today Study. Weight-control behaviors, including dietary approaches and physical activity, were self-reported in 2001 and were used to predict weight change from 2001 to 2005. RESULTS In 2001-2002, 23.7% of female adolescents and young adults were trying to maintain their weight and another 54.4% were trying to lose weight. Approximately 25% used each of the following weight-control strategies: not eating snacks, following low-calorie or low-fat diets, and limiting portion sizes. In addition, 47.7% reported exercising at least occasionally for weight control. During 4 y of follow-up, participants gained an average of 3.3 kg. None of the dietary approaches to weight control predicted less weight change; however, females who exercised > or =5 d/wk gained significantly less weight than did their peers (-0.9 kg; 95% CI: -1.4, -0.4). The most successful strategy for weight-gain prevention among the females was to limit portion sizes (-1.9 kg; 95% CI: -2.6, -1.1) combined with frequent exercise. CONCLUSIONS Our results suggest that physical activity is a necessary strategy for long-term weight control among adolescents and young adult females. Combining dietary weight-control approaches with physical activity is the most effective method for reducing weight gain.