Lifestyle intervention improves fitness independent of metformin in obese adolescents.

PURPOSE

Obesity in adolescence increases the risk for early adult cardiovascular disease. We recently showed that 6 months of diet, exercise, and metformin resulted in reductions in adiposity and that diet/exercise alone reduced proinflammatory factors and intrahepatic fat in pubertal children with uncomplicated obesity. The purpose of the present study was to determine whether changes in cardiorespiratory fitness (CRF) after 6 months of structured diet and exercise (DE) or DE plus metformin are related to the previously observed changes in adiposity, markers of inflammation, and intrahepatic fat.

METHODS

Sixteen obese pubertal adolescents between the ages of 10 and 17 were randomized into a structured lifestyle program consisting of DE or DE plus metformin. Subjects performed aerobic and resistance exercise 3 d·wk⁻¹, 30 min per session. Cycle ergometer maximal oxygen consumption (V˙O2max), body composition, blood markers (glucose, insulin, homeostatic model assessment-insulin resistance, interleukin-6, hsCRP), and intrahepatic fat were measured at baseline and 6 months.

RESULTS

In the cohort, as whole-body weight decreased by 4.0% (P = 0.009), body mass index decreased by 4.9% (P = 0.003), percent body fat decreased by 8.8% (P < 0.001), and V˙O2max improved in 10 of 16 subjects. The addition of metformin provided no further effect on body composition, CRF, or inflammatory factors. More favorable changes in adiposity, adiponectin, and a trend toward blood glucose and interleukin-6 concentrations (P = 0.07) were observed in subjects who increased V˙O2max at 6 months (n = 10) compared with no change in these variables in those who did not improve V˙O2max.

CONCLUSIONS

Metformin did not provide benefits above lifestyle modification for improving CRF in obese adolescents. Improvements in V˙O2max seem to be associated with more favorable metabolic outcomes.