title: Energy requirements of middle-aged men are modifiable by physical activity.
abstract: BACKGROUND
  Energy requirements for weight maintenance decrease with age. Often, this decline is not proportionately matched by reduced energy intake, resulting in weight gain.
  
  
  OBJECTIVE
  We hypothesized that energy requirements for total daily weight maintenance in healthy, sedentary, middle-aged men would increase after regular aerobic exercise or aerobic exercise plus weight loss to levels comparable with those in middle-aged athletes.
  
  
  METHODS
  Weight-maintenance energy requirements were determined during weight stability (+/- 0.25 kg) in 14 lean, sedentary (LS) men; 18 obese, sedentary (OS) men; and 10 male athletes of comparable ages (x +/- SEM: 58 +/- 1 y). Studies were done at baseline and after 6 mo of aerobic exercise (LS men) or aerobic exercise plus weight loss (OS men) or 3 mo of deconditioning (athletes).
  
  
  RESULTS
  The interventions raised maximal oxygen uptake (VO2max) by 15% in the LS men and by 13% in the OS men and decreased it by 14% in athletes (all P < 0.01), eliminating the differences among groups at baseline. Body fat was reduced significantly in LS and OS men; fat-free mass decreased in OS men. Average daily energy requirements increased by 8% in LS men and by 5% in OS men (both P < 0.01) to levels comparable with the baseline requirements of athletes and correlated with VO2max (r2 = 0.22, P < 0.0001) and fat-free mass (r2 = 0.05, P < 0.02) across the range of VO2max achieved by all subjects.
  
  
  CONCLUSIONS
  Under free-living conditions, aerobic exercise eliminated the difference in weight-maintenance energy requirements between middle-aged sedentary and athletic men, suggesting that energy requirements of healthy, middle-aged men are modifiable by regular physical activity.
authors.affiliation: Geriatrics Research, Education and Clinical Center, and Geriatrics Service, Baltimore Veterans Affairs Medical Center, MD 21201-1524, USA. lbunyard@umaryland.edu
authors.forename: L B
authors.initials: LB
authors.lastname: Bunyard
authors.forename: L I
authors.initials: LI
authors.lastname: Katzel
authors.forename: M J
authors.initials: MJ
authors.lastname: Busby-Whitehead
authors.forename: Z
authors.initials: Z
authors.lastname: Wu
authors.forename: A P
authors.initials: AP
authors.lastname: Goldberg
mesh_terms: D000273:Adipose Tissue; D000368:Aged; D001824:Body Constitution; D004032:Diet; D002149:Energy Intake; D015444:Exercise / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009751:Nutritional Requirements; D010101:Oxygen Consumption; D010809:Physical Fitness / Q000502:physiology*; D015431:Weight Loss