Sex differences in the associations of physical activity and macronutrient intake with child body composition:

Abstract

Overweight/obesity is prevalent among children in the Pacific Islands, but its aetiology is poorly understood. Few studies have considered body composi tion in addition to body mass index–based measures. Objectives: To describe body composition among Samoan children and determine sex specific associations among dietary intake, physical activity, and body composition. Methods: Body composition (percent body fat [%BF], lean mass, and trunk-to peripheral fat ratio) of n = 83 Samoan children (3-7 y) was assessed using dual-energy X-ray absorptiometry. Children completed 7 days of objective physical activity moni toring. Mothers reported child nutritional intake using a 115-item food frequency questionnaire. Stepwise generalized linear regression was used to determine indepen dent associations of nutritional intake and physical activity with body composition. Results: Samoan children had higher average %BF than reported among other ethnic groups but lower trunk-to-peripheral fat ratios. In sex-stratified analyses, quartile of carbohydrate intake was negatively associated with %BF (β = −2.02 SE = 0.58; P < .001) in girls only. Among boys, physical activity (quartile of accelerometer counts per minute) was negatively associated with %BF (β = −1.66 SE = 0.55; P < .01). Conclusions: Sex differences in the associations among nutritional intake, physical activity, and body composition may be important to consider as interventions are developed to address overweight/obesity among Samoan children.