A worksite program for overweight middle-aged men achieves lesser weight loss with exercise than with dietary change.

OBJECTIVE: To compare changes in total and regional body composition using dual energy X-ray absorptiometry (DEXA) after subjects lost weight through change in diet or exercise.
DESIGN: A 12-month, randomized, controlled study of two weight-loss interventions-low-fat diet ad libitum or moderate, unsupervised exercise-in free-living, middle-aged men. Compliance was determined at monthly measurement sessions through food records and activity logs; DEXA scans were performed every 3 months. SUBJECTS/
SETTING: Fifty-eight overweight men (mean body mass index = 29.0 +/- 2.6; mean age = 43.4 +/- 5.7 years) recruited from a national corporation were assigned randomly to diet, exercise, or control groups.
INTERVENTIONS: One group reduced dietary fat to 26.4% of energy intake but kept activity unchanged; another group self-selected aerobic exercise (three sessions per week at 65% to 75% maximum heart rate) but kept diet unchanged. A control group maintained weight. MAIN OUTCOME MEASURES: At 12 months, measurements of weight, total and regional fat mass and lean mass, energy intake, and percentage dietary fat; physical activity indexes. STATISTICAL ANALYSES: Results were analyzed using paired t tests and analysis of variance.
RESULTS: Mean weight loss was 6.4 +/- 3.3 kg in dieters and 2.6 +/- 3.0 kg in exercisers; control subjects maintained weight. DEXA scans revealed that 40% of dieters' weight loss was lean tissue; more than 80% of weight lost by exercisers was fat. Exercisers maintained limb lean tissue and lost fat mass.
CONCLUSIONS: Greater total weight and lean tissue loss occurred when subjects lost weight through a low-fat diet consumed ad libitum than when subjects participated in unsupervised aerobic exercise. Use of DEXA enabled identification of progressive total and regional changes in fat and lean tissue.

RCT Entities:   Population Interventions Outcomes