Addition Of Exercise Training To Dietary Weight Loss Reduces Abdominal, But Not Gluteal Adipocyte Size

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Total and abdominal obesity are linked with elevated metabolic and cardiovascular risk. Hypertrophied abdominal subcutaneous adipocytes correlate directly with hyperglyceridemia, glucose intolerance, and hyperinsulinemia, and predict the development of type 2 diabetes. Lifestyle modifications such as dietary weight loss and exercise have been advocated for the treatment of obesity and adiposity-associated complications. It is unknown if addition of exercise training to dietary weight loss is more effective to reduce regional adipocyte size. PURPOSE To determine if hypocaloric diet, diet plus low-intensity exercise, and diet plus high-intensity exercise differentially influence abdominal and gluteal subcutaneous adipocyte size in obese individuals. METHODS Twenty-eight obese older women (BMI=33.5±3.5 kg/m2, age=58±6 years) completed 5 months of hypocaloric diet alone (D, n=8), diet plus low-intensity aerobic exercise (45–50% VO2max, 55 min/day, 3 days/week) (DL, n=9), or diet plus high-intensity aerobic exercise (70–75% VO2max, 30 min/day, 3 days/week) (DH, n=11). The calorie deficits of all women were adjusted to −2800 kcal/week. Body composition testing and adipose tissue biopsies were conducted before and after the interventions. Abdominal and gluteal subcutaneous adipocyte size was determined. RESULTS All 3 interventions reduced body weight (Ps<0.001), fat mass (Ps<0.001), percent fat (Ps<0.001), and waist (Ps<0.001) and hip (Ps<0.01) circumferences. There were no group differences in changes of these measures. D did not change abdominal subcutaneous adipocyte size (109.61±11.16 to 114.88±8.17 microns), whereas both DL (118.30±7.45 to 108.64±6.51 microns, P<0.001) and DH (122.40±8.75 to 114.97±6.57 microns, P <0.01) significantly reduced abdominal adipocyte size. Changes in abdominal adipocyte size in DL (−9.66±5.45 microns) and DH groups (−7.43±5.66 microns) were significantly different from that of the D group (5.28±11.41 microns). Only DH reduced gluteal subcutaneous adipocyte size (125.41±5.95 to 116.82±9.84 microns, P<0.01). However, no group differences were found in changes of gluteal subcutaneous adipocyte size. CONCLUSION Addition of exercise training to dietary weight loss reduces abdominal, but not gluteal subcutaneous adipocyte size in obese individuals. The preferential reduction of abdominal adipocyte size by exercise training is of importance for the treatment of health complications associated with abdominal adiposity. (Supported by NIH grants R01-AG/DK20583, P30-AG21332, and M01-RR07122)