Relationship of pressure to be thin with gains in body weight and fat mass in adolescents

Background: Sociocultural pressure to be thin is commonly reported by adolescents; yet, to what extent such pressure is associated with weight gain has not been evaluated longitudinally. Objective: Examine whether pressure to be thin was positively associated with weight and fat gain in adolescents. Methods: Participants were 196 healthy adolescent (age 15 ± 1 years old) girls (65%) and boys of varying weights (BMI 25 ± 7 kg/m²) studied at baseline and 1-year follow-up. At baseline, adolescents and their mothers reported pressure to be thin by questionnaire. At baseline and follow-up, BMI was calculated, and fat mass was assessed with air displacement plethysmography. Multiple regression was used to examine associations between baseline pressure to be thin and 1-year changes in BMI and fat mass. Results: Accounting for multiple covariates, including baseline BMI or fat, adolescent-reported pressure from parents and peers and mother-reported pressure toward their teen were associated with greater gains in either adolescent BMI or fat (ps <.05). Adolescent weight status was a moderator of multiple effects (ps <.05). Conclusions: Parental and peer pressure to be thin were associated with increases in BMI and fat mass during adolescence, particularly in heavier adolescents. Further research is necessary to clarify how this association operates reciprocally and to identify underlying explanatory mechanisms.