title: Effects of Weight Loss on Lean Mass, Strength, Bone, and Aerobic Capacity.
abstract: This study aimed to evaluate the hypothesis that exercise attenuates the reductions in lean mass, muscle strength, bone mineral density, and V˙O2max that accompany modest weight loss induced by calorie restriction (CR).
  
  
  
  Overweight, sedentary women and men (n = 52, 45-65 yr) were randomized to 6%-8% weight loss by using CR, endurance exercise training (EX), or both (CREX). The CR and the CREX groups underwent counseling to reduce energy intake by 20% and 10%, respectively. The EX and the CREX groups exercised 7.4 ± 0.5 and 4.4 ± 0.5 h·wk, respectively. Before and after 16.8 ± 1.1 wk of weight loss, lean mass and bone mineral density were measured with dual-energy x-ray absorptiometry, strength was measured with dynamometry, and aerobic capacity (V˙O2max) was measured with indirect calorimetry during maximal-intensity treadmill exercise.
  
  
  
  Weight loss was ~7% in all groups. Decreases in whole-body (~2%, P = 0.003) and lower extremity (~4%, P < 0.0001) lean mass occurred in the CR group (both P < 0.05). Despite similar weight loss, these reductions were attenuated in the CREX group (~1%, P = 0.44 and ~2%, P = 0.05, respectively) and absent in the EX group. Absolute aerobic capacity decreased ~6% in the CR group (P = 0.04), was unchanged in the CREX group (P = 0.28), and increased ~15% in the EX group (P < 0.0001). No changes in muscle strength or bone were observed.
  
  
  
  Modest weight loss (~7%) induced by 20% CR in overweight women and men decreases lean mass and reduces absolute V˙O2max. Exercise protects against these effects. Although the CR-induced changes might be considered physiologically appropriate for a reduced body weight, exercise preserves and/or improves these parameters during weight loss, which likely improves physical function. These findings support the notion of using exercise as an important component of weight loss programs.
authors: 1Department of Nutrition and Dietetics, Saint Louis University, St. Louis, MO; 2Division of Geriatrics and Nutritional Science, Washington University School of Medicine, St. Louis, MO; 3Department of Physical Therapy and Athletic Training, Saint Louis University, St. Louis, MO; 4Division of Endocrinology, School of Medicine, Saint Louis University, St. Louis, MO; and 5Division of Endocrinology, Diabetes, and Metabolism, Baylor College of Medicine and Michael E DeBakey VA Medical Center, Houston, TX.
authors: Edward P
authors: EP
authors: Weiss
authors: Richard C
authors: RC
authors: Jordan
authors: Ethel M
authors: EM
authors: Frese
authors: Stewart G
authors: SG
authors: Albert
authors: Dennis T
authors: DT
authors: Villareal
mesh_terms: D000368:Aged; D015992:Body Mass Index; D015519:Bone Density; D031204:Caloric Restriction; D004734:Energy Metabolism / Q000502:physiology; D005081:Exercise Therapy; D006801:Humans; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology*; D050177:Overweight / Q000628:therapy*; D010101:Oxygen Consumption / Q000502:physiology*; D064797:Physical Conditioning, Human; D015431:Weight Loss / Q000502:physiology*