Race and gender differences in the association of dieting and gains in BMI among young adults.

Abstract

To assess the relationship between dieting and subsequent weight change and whether the association varies by gender or race/ethnicity. Male (n = 4100) and female (n = 4302) participants in the National Longitudinal Study of Adolescent Health who provided information on weight and height at baseline and two follow-up assessments and were not missing information on weight control strategies or race were studied. Generalized estimating equations were used to assess whether dieting to lose or maintain weight at Wave I or II predicted BMI (kg/m(2)) change between adolescence and young adulthood (Wave II to III). Analyses were stratified by gender and took sampling weights and clustering into account. At Wave I, the mean age of the participants was 14.9 years. Approximately 29.3% of female participants and 9.8% of male participants reported dieting in Wave I or II. Fewer African Americans than whites (6.2% vs. 10.0% and 25.5% vs. 31.2%, p = 0.007 and p = 0.02, among males and females, respectively) reported dieting. Between Waves II and III, participants gained on average 3.3 kg/m(2). Independent of BMI gain during adolescence (Waves I to II), female participants who dieted to lose or maintain weight during adolescence made larger gains in BMI during the 5 years between Waves II and III (mean additional gain, 0.39 kg/m(2); 95% confidence interval, 0.08 to 0.71) than their nondieting peers. The association was not significant among the male participants. The association was largest among African-American female participants. The results suggest that not only is dieting to lose weight ineffective, it is actually associated with greater weight gain, particularly among female adolescents. Female African-American dieters made the largest BMI gains.