Short-term aerobic exercise training increases postprandial pancreatic polypeptide but not peptide YY concentrations in obese individuals.

OBJECTIVE: Short-term exercise training improves glycemic control, but the effect of short-term training on postprandial satiety peptide responses or perceived satiety remains unknown. We tested the hypothesis that short-term aerobic exercise training (15 days) would alter postprandial pancreatic and gut peptide (pancreatic polypeptide (PP) and peptide YY (PYY)) responses and perceived appetite and satiety in obese individuals. SUBJECTS: Thirteen healthy obese men and women (age: 42±2 years; body mass index: 30-45 kg m(-2)). MEASUREMENTS: Subjects were studied before and after 15 days of training (walking 1 h at 70-75% VO(2peak)). On the study day, subjects consumed 1500 kcal as six meals (250 kcal: 9 g protein, 40 g carbohydrate, 6 g fat), while blood samples and satiety measurements were taken at baseline and every 20 min for 12 h. Blood was analyzed for PP, PYY, glucose and insulin levels. Appetite and satiety was assessed with a visual analog scale throughout the day. RESULTS: Incremental area under the curve (iAUC) for PP increased significantly with training (pre: 2788±753; post: 3845±830 pg ml(-1)·per min for 12 h; P<0.001), but there was no difference in the PP response to each meal. The initial PP response to the first meal increased (ΔPP(min 20-0): pre 86±25; post 140±36 pg ml(-1); P<0.05) with training. PYY iAUC showed no significant changes with training but showed a significant main effect of time across meals, with the largest response being to the first meal (P<0.005). There were no changes in satiety, glucose or insulin levels with training. CONCLUSION: Short-term exercise training increases postprandial PP concentrations in obese individuals; however, PYY levels and glycemic control remain unaffected. Both PP and PYY show meal-induced increases at all meals, but PYY has a greater response at the first meal with reduced responses at subsequent meals.

Weight-loss-associated changes in bone mineral density and bone turnover after partial weight regain with or without aerobic exercise in obese women.

BACKGROUND/OBJECTIVES: Moderate, long-term weight loss results in the loss of bone mass in overweight or obese premenopausal women. However, whether these changes persist during weight maintenance or regain remains to be determined. SUBJECTS/METHODS: Overweight or obese (body mass index: 25.8-42.5 kg/m(2)) women (n=40) with at least two risk factors for the metabolic syndrome participated in this 12-month study that examined the effects of prescribed weight loss and regain, with or without exercise, on bone turnover and on bone mineral density (BMD) in a subset of participants (n=24). During the first 6 month, participants lost ≈ 10% of their initial body weight via energy restriction and supervised aerobic exercise. Following weight loss, participants were randomly assigned to either an exercise or a no exercise treatment for the regain (+50% of weight lost) phase. A one-way (time) repeated measures one-factor analysis of variance (RMANOVA) tested the effects of weight loss on BMD and bone turnover, and a two-way RMANOVA (time, exercise) was used to examine the effects of exercise during weight regain. RESULTS: Hip (P=0.007) and lumbar spine (P=0.05) BMD decreased with weight loss, and remained reduced after weight regain with or without exercise. Likewise, the weight-loss-associated increases in osteocalcin (P<0.001) and C-terminal peptide of type I collagen (P<0.001) persisted following weight regain, independent of exercise. CONCLUSIONS: The results of the present study, which is the first to examine changes in bone mass and turnover during carefully controlled weight regain, suggest that weight-loss-induced perturbations in bone mass and turnover persist after partial weight regain, regardless of whether regular weight-bearing aerobic exercise was continued.