Diminished insulin resistance with weight loss in severely overweight youth.

Background: The influence of weight loss on insulin resistance was determined in severely overweight (BMI Z-score: 7.3 +/- 0.9 z-units) hyperinsulinemic (mean fasting serum insulin concentration: 33.0 +/- 6.7 mu IU/mL) youth. Methods: Eight overweight youth and obese parents were studied at baseline and then at 6 and 12 months after behavioral weight loss therapy. Non-treated lean youth (n = 8) served as controls for normal interval growth. The groups were matched for sex, race, age (10.2 versus 10.1 years), and pubertal maturation, and evaluated for weight, height, blood pressure, and the homeostasis model of insulin resistance (HOMA-IR). Results: Overweight youth had reductions (p <= 0.05) in % overBMI (BMI - BMI at 50th percentile)/BMI at 50th percentile * 100), HOMA-IR, and systolic blood pressure after 6 months of treatment. These were sustained until the 12-month follow-up, while the control group did not change. Youth with the greatest reduction in % overBMI had the greatest reduction in HOMA-IR (r = 0.59, p <= 0.05), and HOMA-IR was directly related (r = 0.56, p = 0.03) to the change in systolic blood pressure. Parents of overweight youth had reductions (p <= 0.05) in % overBMI. There was a robust relationship between child and parent % overBMI change (r = 0.82, p <= 0.05). Conclusions: Insulin resistance can be reduced in severely overweight youth following 6 months of weight loss therapy and maintained for 12 months. The relationship between child and parent weight change supports the role of the parent in modeling appropriate weight loss behaviors and restructuring the environment so that weight loss is possible.