The contribution of dietary macronutrients and energy intake to body mass index of 3-13 year children, Tehran Lipid and Glucose Study (TLGS)

Obesity is considered to be a chronic disease with multifactorial etiology. The purpose of this study was to identify predictors of obesity among total energy and macronutrient intakes in a group of Tehranian children. 390 children aged 3-13 years (221 boys, 169 girls) were selected randomly from among participants of the Tehran Lipid and Glucose Study. Body size was measured based on weight and height using body mass index (BMI, Kg/m2). Children with BMI over 85th centiles were considered overweight. Dietary intake data were assessed by trained interviewers using two non-consecutive 24-hour recalls. Under-reporters of energy intake were excluded from the study. Dietary composition was assessed in terms of calorie-adjusted amount of macronutrients intake and absolute dietary intakes, and data were entered in multiple regression models controlling for confounding variables and mutual effects of other macronutrients. The average BMIs of children 3-8 y and 9-13 y were 15.2±1.9 and 17.7±3.8(Kg/m2), respectively. Prevalence of overweight in girls was higher than in boys (19.2% Vs 16%, p<0.01). Absolute and adjusted dietary protein intakes were positively associated with BMI in boys aged 3-8 y (ß=0.63,p<0.05 and ß= 0.4, p<0.05). In both sexes only the absolute amount of fat intake contributed to BMI (ß=0.2 p<0.001 and ß=0.3, p<0.01). Adjusted carbohydrate intake was found to be negatively associated with BMI in boys (ß= -0.6, p<0.001). The results and evidence indicate that a positive association exists between protein intake and BMI in 3-8 year old children, whereas only absolute amounts of fat intake are positively associated with obesity. Obesity was found to be inversely correlated with carbohydrate intake.