Gradual increase in energy intake over 8 weeks with voluntary wheel running limits body weight change in male rats.

Abstract

The influence of appetite and energy intake on energy compensation in response to chronic exercise remains poorly understood. This study examined the temporal impact of habitual exercise on energy intake and the homeostatic appetite regulators that influence energy compensation. Twelve-week-old male Sprague Dawley rats (n=30) fed an AIN-93M diet were randomised into 1 of 3 groups: 1) sedentary control (SED); 2) voluntary wheel exercise (EX); and 3) sedentary, weight-matched to aerobic exercise (SED-WM) for 8 weeks. Measures of energy intake, body weight, and adiposity were assessed. Appetite-regulating hormones acyl-ghrelin, active GLP-1, leptin, and insulin were measured in response to an oral glucose tolerance test. Rats with running wheels completed an average of 192kms over 8 weeks. While energy intake was initially reduced in EX, energy intake gradually increased with exercise training after week 1 (P<0.05). Body weight was lower in EX relative to SED from weeks 3-5, but did not differ at the end of the study. Fat mass and long-term satiety hormones leptin and insulin were lower in EX (P<0.05). No differences were observed in concentrations of the satiety hormone active GLP-1 or the orexigenic hormone acyl-ghrelin. Short-term homeostatic regulators of appetite do not appear to be altered with exercise training. The reduction in adiposity and associated decrease in tonic satiety hormones leptin and insulin are likely contributors to the coupling of energy expenditure with energy intake over time with voluntary exercise.