title: Aerobic exercise is necessary to improve glucose utilization with moderate weight loss in women.
abstract: OBJECTIVE
  To determine the effects of weight loss (WL) alone and combined with aerobic exercise on visceral adipose tissue (VAT), intramuscular fat, insulin-stimulated glucose uptake, and the rate of decline in free fatty acid (FFA) concentrations during hyperinsulinemia.
  
  
  METHODS
  We studied 33 sedentary, obese (BMI = 32 +/- 1 kg/m(2)) postmenopausal women who completed a 6-month (three times per week) program of either WL alone (n = 16) or WL + aerobic exercise (AEX) (n = 17). Glucose utilization (M) was measured during a 3-hour hyperinsulinemic-euglycemic clamp (40 mU/m(2) per minute). M/I, the amount of glucose metabolized per unit of plasma insulin (I), was used as an index of insulin sensitivity.
  
  
  RESULTS
  Body weight, total fat mass, and percentage fat decreased similarly in both groups (p < 0.01). VAT, subcutaneous abdominal adipose tissue, mid-thigh subcutaneous fat, and intramuscular fat decreased to a similar extent in both groups and between 14% and 27% after WL and WL+AEX (p < 0.05). WL alone did not change M or M/I; however, M and M/I increased 15% and 21% after WL+AEX (p < 0.05). Fasting concentrations and rate of decline of FFA did not change in either group. In stepwise regression models to determine the independent predictors of changes in M and M/I, the change in VAT was the single independent predictor of M (r(2) = 0.30) and M/I (r(2) = 0.33).
  
  
  CONCLUSIONS
  Intramuscular fat decreases similarly with 6 months of moderate WL alone or with aerobic exercise in postmenopausal women. In contrast, only WL combined with exercise results in increased glucose utilization and insulin sensitivity. These findings should be validated in a larger population.
authors.affiliation: Department of Medicine, Division of Gerontology at the University of Maryland School of Medicine, VA Maryland Health Care System, Baltimore, MD 21201, USA. aryan@grecc.umaryland.edu
authors.forename: Alice S
authors.initials: AS
authors.lastname: Ryan
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Nicklas
authors.forename: Dora M
authors.initials: DM
authors.lastname: Berman
mesh_terms: D000368:Aged; D015415:Biomarkers; D050218:Body Fat Distribution; D003131:Combined Modality Therapy; D015444:Exercise / Q000502:physiology*; D005227:Fatty Acids / Q000097:blood; D005260:Female; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D007333:Insulin Resistance; D050152:Intra-Abdominal Fat; D008875:Middle Aged; D009765:Obesity / Q000178:diet therapy / Q000628:therapy*; D017698:Postmenopause; D015431:Weight Loss / Q000502:physiology*
chemical_list: D015415:Biomarkers; D005227:Fatty Acids; D005947:Glucose