Effects of dairy consumption and exercise on body composition in overweight/obese adolescent females: The I.D.E.A.L. (Improving Diet, Exercise, and Lifestyle) for Adolescents Study

Abstract

Exercise training is known to decrease fat mass and increase lean mass in adolescents and adults. In adults, the consumption of dairy foods, as part of a lifestyle intervention, can promote favourable body composition changes. However, results of the few studies examining the combined effects of exercise and dairy consumption on body composition in adolescents are inconclusive. The purpose of our study was to determine whether increased dairy consumption, along with structured exercise training and dietary guidance within a weight management program, can promote favourable changes in body composition, anthropometry and cardiovascular fitness in overweight/obese adolescent females. Sixty-one adolescent females (age: 14.8±2.2 y; BMI: 29.3±5.1 kg/m2) were randomized to 3 groups: recommended dairy (RDa; n=24); low dairy (LDa; n=22); control (GCon; n=8), and 54 participants completed the study. The RDa and LDa groups participated in a 12-week, individualized, eucaloric, lifestyle modification intervention consisting of mixed-mode exercise 3x/week, and 5 nutritional counselling sessions with a registered dietitian. RDa group was provided 4 servings/day of dairy (as milk, Greek yogurt and cheese), while LDa maintained habitually low intakes of 0-2 servings/day. Seven-day food records were collected at weeks 0 and 12. Body composition, waist/hip circumference, and VO2peak were assessed for all groups at weeks 0 and 12. Both RDa and LDa decreased body fat (-1.7±1.5%, -1.2±1.1%, respectively), fat mass (-1.3±2.1kg, -1.1±2.0kg, respectively) and subcutaneous fat thickness (-12.5±10.0mm, -9.1±9.4mm, respectively) compared with the GCon (0.3±1.3%, 0.8±1.8kg, 3.0±8.0mm, respectively) (p ≤0.002 for all). RDa decreased fat mass (kg) more than LDa (p=0.001). Both RDa and LDa gained more lean mass (1.5±1.9kg, 0.7±1.6kg, respectively) than GCon (0.5±1.4kg). RDa increased lean mass more than LDa (p≤0.001). VO2peak (ml/min/kg) did not differ between groups following the intervention (p=0.093). These findings suggest that the inclusion of a variety of dairy foods in the diet of overweight/obese adolescent girls, as part of a weight management intervention program, is beneficial to the overall improvement in body composition.