Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/30/2006
Publication Date: 6/9/2006
Citation: Sunehag, A.L., Wang, Z.J., Green, T.F., Bier, D.M., Haymond, M.W. 2006. A 12 weeks exercise program resulted in reduced visceral fat and fasting insulin but not total and intramyocellular fat in Hispanic obese adolescents [absract]. 2006 Pediatric Academic Societies Meeting. Paper No. 753346.
Technical Abstract: Background: The high prevalence of obesity in children and adolescents is a serious public health concern. Weight loss is known to improve insulin sensitivity but is difficult to achieve. The independent effects of exercise on body fat distribution and insulin sensitivity in the absence of overall weight loss is less well understood, particularly in obese adolescents. Objective: To test the hypothesis that a moderate aerobic exercise program without intended weight loss has beneficial effects on visceral, hepatic and intramyocellular fat accumulation and circulating insulin concentrations in obese Hispanic adolescents. Design/Methods: Eight obese Hispanic adolescents (2 m/6 f; 15+/-1 y; 83.3+/-6.5 kg; 37.2+/-2.3 percent body fat) completed a 12-week aerobic exercise program (x 4/week; 30 min/session at 70-80 percent of their VO2 max). Two sessions/week were supervised, while the remaining two weekly sessions were performed at home without supervision. Each subject wore a heart rate monitor while exercising to validate compliance. Heart rate data were downloaded and reviewed on a weekly basis. Total body fat was measured before and after the exercise program by DXA. Visceral fat was quantified by MRI, and hepatic and intramyocellular fat by MRS. Results: Body weight was maintained and total fat remained unchanged after the exercise program. In contrast, visceral fat was reduced in all subjects from 48.0+/-8.9 to 40.9+/-7.5 cm3; p=0.01 (mean+/-SE). Liver fat ranged from 30.4 to 1.0 arbitrary units (MRS; liver fat peak/to water peakx100). In three subjects with the highest values (30.4, 16.0, and 6.4), exercise reduced liver fat by 49+/-8 percent but there was no significant change in the remaining subjects. Intramyocellular fat was not affected by the exercise program. Plasma insulin was highly correlated with visceral fat (R2=0.95; p=0.00003) and decreased from 20.8+/-3.7 to 17.6+/-2.9 uU/mL (p=0.02) as a result of the exercise, but glucose was not affected (4.8+/-0.1 and 4.9+/-0.1 mM), indicating improvement of insulin sensitivity. Conclusions: In obese adolescents, a moderate exercise program reduces visceral fat and improves insulin sensitivity in the absence of weight or total body fat loss. Reduction of sedentary activity leading to visceral fat loss may also improve hepatic steatosis.