The prevalence of obesity is rapidly escalating worldwide and obesity is closely linked to the developmentof insulin resistance, metabolic syndrome and type 2 diabetes. Negative energy balance is key in reversing themetabolic defects associated with obesity and produces an array of health benefits that cannot be matched byany one drug that is currently on the market. These include improved lipid profiles and insulin sensitivity,reduced ectopic lipid deposition, blood pressure and reduced inflammatory cytokine production. However, theoptimal method to achieve negative energy balance is debated.

Here I compare studies of reduced energy intaketo increased energy expenditure, and in particular focus on the differential effects of these interventions on leanmass preservation, energy metabolism and insulin action.In free living studies, moderate calorie restriction (CR) nearly always produces greater weight loss, butthere is evidence to suggest that aerobic exercise may provide equal or greater health benefits and is better tomaintain weight loss following CR. Here, I report findings from the CALERIE studies, where we compared25% CR versus 12.5% CR plus 12.5% increase in energy expenditure by aerobic exercise training understringent laboratory conditions for 6-months in healthy overweight individuals. In this study, energyrequirements were carefully assessed, all foods were provided for 3.5 months whilst individuals attended weeklytraining sessions to learn how to accurately count calories, and all of the exercise sessions were conducted undersupervision.

http://www.apps.org.au/Proceedings/41/139P/139P.pdf