Physical Activity is Associated with Lower Adiposity Independent of Diet Quality in Adolescent Girls

BACKGROUND Total and site‐specific adiposity, such as visceral and skeletal muscle fat, have been associated with increased cardiovascular disease risk in adults, but data are lacking for youth. Calorically dense diets are major contributors to the development of childhood obesity and metabolic diseases. OBJECTIVE To assess the relationships between diet quality (DQ), measured by the Youth Healthy Eating Index (YHEI), physical activity (PA), and measures of total and site‐specific adiposity in 211 healthy girls aged 8‐13 years. METHODS Muscle density (MD, mg/cm 3 ), surrogate for fat infiltration, was measured at tibia and femur sites using peripheral quantitative computed tomography. Total body and android fat (surrogate for visceral fat) were measured by dual energy x‐ray absorptiometry. Diet was assessed using the validated semi‐quantitative Harvard Youth/Adolescent Food Frequency Questionnaire (YAQ). DQ was assessed from the YHEI, developed based on the YAQ. PA was assessed using a past year PA questionnaire. RESULTS Multiple linear regressions with DQ, maturity, total energy intake, and PA were used to predict MD, total body fat (BF), android fat (AF), and body mass index (BMI) in separate models. DQ was not a significant predictor of adiposity. PA was positively associated with calf MD (p 蠄 0.01, β=0.62) and thigh MD (p 蠄 0.01, β=0.77) and negatively associated with BMI (p蠄0.05, β=‐0.02), AF (p蠄0.01, β=‐4.82), and BF (p蠄0.01, β=‐3.74). CONCLUSION PA is associated with lower adiposity independent of DQ, total energy intake, ethnicity, and maturation. Grant Funding Source: NIH: HD050775