Energy requirements of middle-aged men are modifiable by physical activity.

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. DESIGN: 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.

Effects of an American Heart Association diet and weight loss on lipoprotein lipids in obese, postmenopausal women.

The sequential effects of an American Heart Association (AHA) Step 1 diet and subsequent weight loss on lipoprotein lipids in obese [body mass index (in kg/m2) > 27], postmenopausal women (n = 48) were determined. Subjects followed a euenergetic AHA Step 1 diet for 2 mo, followed by a weight-loss diet (deficit of 1.0-1.5 MJ/d) for 6 mo. The AHA diet lowered concentrations of total (7%), low-density-lipoprotein (LDL) (6%), and high-density-lipoprotein (HDL) (14%) cholesterol (P < 0.01). Weight loss (-5.6 +/- 0.7 kg; P < 0.01) increased plasma triacylglycerol concentrations (9%; P < 0.01) and increased HDL-cholesterol concentrations (8%; P < 0.01) compared with changes after the AHA diet, but there were no changes in total or LDL cholesterol. The combined AHA diet and weight-loss interventions lowered triacylglycerol (10%) and total (6%), LDL (6%), and HDL (7%) cholesterol. These changes correlated indirectly with the baseline concentration for each lipid. When the women were divided on the basis of initial LDL-cholesterol concentration, the AHA diet and weight-loss interventions reduced (P < 0.01) triacylglycerol (19%), total cholesterol (13%), and LDL cholesterol (14%) in the women with hypercholesterolemia but not in normocholesterolemic or midly hypercholesterolemic women. Thus, an AHA Step 1 diet and subsequent weight loss improve lipoprotein lipid profiles of obese, postmenopausal women with hypercholesterolemia. However, because it lowers HDL cholesterol, a low-fat diet without substantial weight loss may not be beneficial for improving lipoprotein lipid risk factors for coronary artery disease in obese, postmenopausal women with normal lipid profiles.

Physiological predictors of increasing total and central adiposity in aging men and women.

BACKGROUND: Increasing levels of total and central body fat with advancing age contribute to the development of cardiovascular and metabolic disease. We examined gender-related differences and physiological predictors of the rate of increase in total and central body fat in men and women. METHODS: We studied 427 healthy men (age range, 17 to 90 years) and 293 women (age range, 18 to 88 years). We measured body fatness by hydrostatic weighing, central adiposity from the waist circumference, peak volume of oxygen utilization (VO2) from a treadmill test, leisure time physical activity (LTA) from a questionnaire, resting metabolic rate and respiratory quotient from indirect calorimetry, and energy intake from 3-day food diaries. RESULTS: Fat mass increased with age, and the rate was greater in women (r = .61; slope = 0.25 kg/y; P < .01) than in men (r = .43; slope = 0.16 kg/y; P < .01). Increasing fat mass in men and women was most strongly associated with declines in peak VO2 and LTA. Controlling for these variables reduced the increase in fat mass from 17% to 3% per decade in men and from 26% to 5% per decade in women. The increase in waist circumference with age was also greater in women (r = .53; slope = 0.28 cm/y) than in men (r = .39; slope = 0.18 cm/y; P < .01). Increasing waist circumference with age in men and women was most strongly associated with declines in LTA and peak VO2, respectively. Control for these variables reduced the age-related increase in waist circumference from 2% to 1% per decade in men and from 4% to 1% per decade in women. We observed no independent contribution of resting metabolic rate, respiratory quotient, menopause status, energy, or macronutrient intake to the age-related increase in fat mass and waist circumference. CONCLUSIONS: Our findings suggest that (1) the age-related increase in fat mass and waist circumference is greater in women than in men and (2) the physiological characteristics that reflect a decline in physical activity-related energy expenditure, rather than resting energy expenditure, are important predictors of the increases in total and central fatness. Lifestyle changes that increase the level of physical activity may be advantageous in blunting age-related increases in total and central body fatness.

Visceral adiposity is associated with increased lipid oxidation in obese, postmenopausal women.

Lipolysis is increased in upper-body obese individuals but it is unclear whether body fat distribution is associated with differences in resting metabolic rate (RMR) and/or substrate oxidation in older women. This study determined whether RMR and lipid oxidation are higher in postmenopausal women with visceral obesity. A single-slice computed tomography scan was taken midway between L4 and L5 in 29 women aged 52-72 y with a fat mass of 29.2-68.8 kg. RMR and lipid oxidation rates were measured by using indirect calorimetry. RMR was related to waist circumference (r = 0.45, P < 0.05), but not to waist-hip ratio (WHR; r = 0.23) or intraabdominal fat area (r = 0.26). However, there was a strong, positive relation between lipid oxidation and intraabdominal fat area (r = 0.57, P < 0.01), waist circumference (r = 0.54, P < 0.01), and WHR (r = 0.42, P < 0.05). These correlations remained significant after statistical adjustment for total fat and fat-free mass. These results suggest that in postmenopausal women higher amounts of intraabdominal fat are associated with an enhanced rate of lipid oxidation independent of total adiposity, but not with alterations in RMR.