Dietary protein, skeletal muscle mass, and obesity risk in adolescent girls

Abstract

Adolescence is a critical period for acquisition of skeletal muscle mass (SMM) as well as the development of obesity. Prospective data on the effect of dietary protein on these outcomes are sparse. The goal of the study is to estimate the effects of dietary protein on adolescent body composition, using data from the National Growth and Health Study, a prospective study of 2379 9–10 year old girls followed for 10 years. 3‐day records were used to assess diet during 8 years of follow up. Bioelectrical impedance data from annual clinic visits were combined with age and height to estimate percent of total body weight from SMM. Analysis of covariance and logistic models were used to control for potential confounding by age, race, SES, height, activity, TV/video viewing time, and age at menarche. Percent body fat in late adolescence declined linearly with increasing quintiles of protein intake (in g/kg/day) in early adolescence (37.2, 32.4, 29.9, 28.7, 27.4 % body fat, respectively, for quintiles 1–5; p‐trend<0.0001). Percent SMM increased from 28.9% to 36.6% with increasing quintile of intake. Compared with the lowest quintile of intake, there was a striking 96% reduced risk (95% CI: 0.02–0.05) of being overweight (BMI ≥ 25 kg/m2) at end of follow up. These results suggest that higher dietary protein intakes may benefit acquisition of SMM and reduce the risk of acquiring excess body fat during adolescence.Grant Funding Source: NIDDK and a small grant