title: A worksite program for overweight middle-aged men achieves lesser weight loss with exercise than with dietary change.
abstract: 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.
  
  
  METHODS
  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.
  
  
  METHODS
  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.
  
  
  METHODS
  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.
  
  
  METHODS
  At 12 months, measurements of weight, total and regional fat mass and lean mass, energy intake, and percentage dietary fat; physical activity indexes.
  
  
  METHODS
  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.
authors.affiliation: Department of Physiology, Royal Melbourne Hospital, University of Melbourne, Parkville, Australia.
authors.forename: J E
authors.initials: JE
authors.lastname: Pritchard
authors.forename: C A
authors.initials: CA
authors.lastname: Nowson
authors.forename: J D
authors.initials: JD
authors.lastname: Wark
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D001823:Body Composition; D018752:Diet, Fat-Restricted; D015444:Exercise; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000178:diet therapy / Q000628:therapy*; D015431:Weight Loss / Q000502:physiology*; D017132:Workplace