Several studies have identified relationships between weight loss and adipokine levels; however none have looked at the combined effect of aerobic exercise training with consumption of a low, or high glycemic diet. We examined the effects of 12-weeks of aerobic exercise combined with either a low- (GI: ~40, LoGIX) or high-glycemic (GI: ~80, HiGIX) diet on plasma leptin and adiponectin (total and high molecular weight - HMW) in 27 older obese adults (age 65±0.5 years; BMI 34.5±0.7 kg/m2).
Insulin sensitivity was calculated from an oral glucose tolerance test (ISIOGTT). Fasting HMW adiponectin and leptin were quantified from plasma samples obtained prior to the ISIOGTT. Glucose and insulin measures were obtained before and every 30 min during the test. Dual-energy X-ray absorptiometry and computerized tomography was used to determine body composition and to quantify subcutaneous and visceral abdominal adiposity, respectively.
Fasting leptin was significantly decreased in both groups (LoGIX, pre: 33.8±4.7, post: 19.2±4.5; HiGIX, pre: 27.9±4.2, post: 11.9±2.2 ng/ml, P=0.004), and HMW adiponectin was significantly increased (LoGIX, pre: 1606.9±34.6, post: 3502.3±57; HiGIX, pre: 3704.8±38.1, post: 4284.3±52.8 pg/ml; P=0.003) following the 12-week intervention. Total body fat was reduced after both interventions, and visceral fat mass was inversely correlated with HMW adiponectin, while subcutaneous fat correlated with leptin.
The data suggest that exercise training, independent of dietary GI, favorably alters HMW adiponectin and leptin secretion, and that a reduction in visceral fat mass is a key factor regulating HMW adiponectin in older obese persons.