Objectives: To determine the effects of equivalent diet‐ or exercise‐induced weight loss and exercise without weight loss on subcutaneous fat, visceral fat, and insulin sensitivity in obese women.Research Methods and Procedures: Fifty‐four premenopausal women with abdominal obesity [waist circumference 110.1 ± 5.8 cm (mean ± SD)] (BMI 31.3 ± 2.0 kg/m²) were randomly assigned to one of four groups: diet weight loss (n = 15), exercise weight loss (n = 17), exercise without weight loss (n = 12), and a weight‐stable control group (n = 10). All groups underwent a 14‐week intervention.Results: Body weight decreased by ∼6.5% within both weight loss groups and was unchanged in the exercise without weight loss and control groups. In comparison with controls, cardiorespiratory fitness improved within the exercise groups only (p < 0.01). Reduction in total, abdominal, and abdominal subcutaneous fat within the exercise weight loss group was greater (p < 0.001) than within all other groups. The reduction in total and abdominal fat within the diet weight loss and exercise without weight loss groups was greater than within controls (p < 0.001) but not different from each other (p > 0.05). Visceral fat decreased within all treatment groups (p < 0.008), and these changes were not different from each other. In comparison with the control group, insulin sensitivity improved within the exercise weight loss group alone (p < 0.001).Discussion: Daily exercise without caloric restriction was associated with substantial reductions in total fat, abdominal fat, visceral fat, and insulin resistance in women. Exercise without weight loss was also associated with a substantial reduction in total and abdominal obesity.

The optimal exercise modality for reductions of abdominal obesity and risk factors for type 2 diabetes in youth is unknown. We examined the effects of aerobic exercise (AE) versus resistance exercise (RE) without caloric restriction on abdominal adiposity, ectopic fat, and insulin sensitivity and secretion in youth. Forty-five obese adolescent boys were randomly assigned to one of three 3-month interventions: AE, RE, or a nonexercising control. Abdominal fat was assessed by magnetic resonance imaging, and intrahepatic lipid and intramyocellular lipid were assessed by proton magnetic resonance spectroscopy. Insulin sensitivity and secretion were evaluated by a 3-h hyperinsulinemic-euglycemic clamp and a 2-h hyperglycemic clamp. Both AE and RE prevented the significant weight gain that was observed in controls. Compared with controls, significant reductions in total and visceral fat and intrahepatic lipid were observed in both exercise groups. Compared with controls, a significant improvement in insulin sensitivity (27%) was observed in the RE group. Collapsed across groups, changes in visceral fat were associated with changes in intrahepatic lipid (r = 0.72) and insulin sensitivity (r = −0.47). Both AE and RE alone are effective for reducing abdominal fat and intrahepatic lipid in obese adolescent boys. RE but not AE is also associated with significant improvements in insulin sensitivity.

Background: The influence of age and sex on the distribution of abdominal adipose tissue for a given waist circumference (WC) is unclear. Objective: The objective was to investigate the influence of age and sex on total (TAAT), visceral (VAT), and abdominal subcutaneous (ASAT) adipose tissue for a given WC. Design: Body composition was assessed by whole-body magnetic resonance imaging in 147 younger men (< 50 y), 83 older men, 171 younger (premenopausal) women, and 80 older (postmenopausal) women with a wide range (16–40; in kg/m²) of body mass indexes. Results: Within each sex, the regression lines between WC and TAAT were not significantly different (P > 0.1) between younger and older groups. Collapsed across age groups, women had more TAAT for a given WC than did men; however, this difference was significantly reduced with increasing WC (P < 0.05). Within each sex, regression lines derived for WC and ASAT were not significantly different between younger and older groups (P > 0.1). Collapsed across age groups, women had 1.8 kg more ASAT for a given WC (P < 0.05) than did men across the range of WCs. Within each sex, older men and women had a significantly greater increase in VAT for a given WC (P < 0.05) than did younger men and women. Furthermore, independent of age group, the slopes for WC and VAT were significantly higher (P < 0.05) in men than in women. Conclusions: There are significant sex differences in TAAT, VAT, and ASAT for a given WC. Furthermore, the relation between WC and VAT is substantially influenced by age.

The prevalence of chronic disease and physical disability among obese elderly persons is high and increasing.^1,2 The economic burden associated with chronic disease or disability is substantial.^2-4 Although the elderly currently constitute less than 13% of the total population,⁵ they account for approximately 35% of the total personal health care costs.⁶ Projections indicating that the US population 65 years and older will increase from 12% in 2000 to 20% in 2030⁵ underscore the urgent need to develop effective strategies designed to manage the risk factors for disease and disability and thereby improve the overall health and quality of life of older adults.

It is unclear whether chronic exercise without caloric restriction or weight loss is a useful strategy for obesity reduction in obese men with and without Type 2 diabetes (T2D). We examined the effects of exercise without weight loss on total and regional adiposity and skeletal muscle mass and composition in lean men and in obese men with and without T2D. Twenty-four men participated in 13 wk of supervised aerobic exercise, five times per week for 60 min at a moderate intensity (∼60% peak oxygen uptake). Total and regional body composition was measured by magnetic resonance imaging. Skeletal muscle composition was determined using computed tomography. Cardiorespiratory fitness was assessed using a graded maximal treadmill test. Body weight did not change within any group in response to exercise (P > 0.1). Significant reductions in total, abdominal subcutaneous, and visceral fat were observed within each group (P < 0.01). The reduction in total and abdominal subcutaneous fat was not different (P > 0.1) between groups; however, the reduction in visceral fat was greater (P < 0.01) in the obese and T2D groups by comparison to the lean group. A significant (P < 0.01) increase in total skeletal muscle, high-density muscle area, and mean muscle attenuation was observed independent of group, and these changes were not different between groups (P > 0.1). Accordingly, whole body fat-to-muscle ratio was increased (P < 0.01) independent of groups. In conclusion, regular exercise without weight loss is associated with a substantial reduction in total and visceral fat and in skeletal muscle lipid in both obesity and T2D.