Lifestyle Intervention Improves Fitness Independent of Metformin in Obese Adolescents

Medicine and Science in Sports and Exercise, 04/18/2012

Rynders C et al. - Metformin did not provide benefits above lifestyle modification for improving cardiorespiratory fitness (CRF) in obese adolescents. Improvements in V'O2max seem to be associated with more favorable metabolic outcomes.


  • 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.


  • 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.

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