Step-Defined Physical Activity Is Associated With Weight Loss and Changes in Body Composition and Fat Distribution in Response to Diet Interventions: The POUNDS Lost Trial

Abstract

\n \n \n To examine whether objectively measured physical activity (PA) is associated with weight loss and changes in body composition and fat distribution in response to weight-loss diet interventions.\n \n \n \n This study included 535 overweight or obese participants randomly assigned to 4 weight-loss diets varying in macronutrient intake with physical activity measured objectively with pedometers in the POUNDS Lost trial. The associations of step defined PA or the changes in PA with the changes in obesity measurements including body weight (BW), waist circumference (WC), body fat composition assessed by the dual-energy X-ray absorptiometry (DEXA) scans, body fat distribution assessed by the computed tomography (CT) were examined at the 6 and 24 months. We also examined whether the associations were modified by diet interventions.\n \n \n \n The increase of step-defined PA was significantly predictive of weight loss and decrease in all measurements of body fat composition and distribution in response to diet interventions over 24 months (P\xa0<\xa00.0001 for all). We also observed significant inverse associations of changes in PA with changes in BW (P\xa0<\xa00.0001), WC (P\xa0<\xa00.0001), body fat composition (P\xa0<\xa00.05 for total fat, total lean, total fat mass %, and trunk fat %) and fat distribution (P\xa0<\xa00.05 for total adipose tissue mass (TAT), visceral adipose tissue mass (VAT), deep subcutaneous adipose tissue mass (DSAT)) from baseline to 6 months, when the maximum weight loss was achieved. Dietary fat or protein intake modified the associations between changes in PA and changes in body weight and waist circumference over 24 months; greater reduction in these measures was observed in participants with high-fat or low-protein diets than those in the low-fat or high-protein diets (P interaction <\xa00.05 for all).\n \n \n \n Our results indicate that objectively measured PA is inversely related to the changes in body weight, body composition, and fat distribution in response to weight-loss diets, and such relation is more evident in people with high-fat or low-protein diets.\n \n \n \n The study was supported by grants from the National Heart, Lung, and Blood Institute, the National Institute of Diabetes and Digestive and Kidney Diseases, the Fogarty International Center, and Tulane Research Centers of Excellence Awards.\n