Grant: Master's Award: Canada Graduate Scholarships

Increasing evidence suggests that obesity and risks for diabetes and heart disease are associated with inactivity and impaired fat metabolism in skeletal muscle. In collaboration with a CIHR funded project called High Impact Strategies towards Overweight Reduction in Youth (HISTORY), we will study determinants of metabolic risk in children. Specifically, the proposed study will evaluate abnormalities in fat metabolism during exercise and its association with high lipid levels and insulin resistance in overweight children. Research on the benefits of regular exercise is important for developing effective prevention and treatment strategies. Fat burned during exercise decreases with puberty in both obese and lean boys, perhaps contributing to the development of obesity at the time of puberty. However, no studies have evaluated the influence of puberty on fat metabolism during exercise in overweight girls. In addition, elevated free fatty acids in the bloodstream of obese individuals may contribute to fat accumulation in skeletal muscle, which is observed as intramyocellular lipid (IMCL) and closely linked with insulin resistance. Thus, we hypothesize that an inability to burn fat during exercise may lead to elevated lipids in the blood and higher IMCL in overweight children. Overweight girls and lean girls matched for pubertal stage and menstrual cycle phase ages 8-18 y will visit the Hospital for Sick Children on 2 occasions. The following parameters will be measured: 1) maximal exercise capacity 2) fat burned over a range of exercise intensities 3) body composition 4) pubertal stage 5) muscle IMCL 6) blood markers and 7) a diabetes test. Evaluating fat metabolism in girls across pubertal development may provide clinical implications for prescribing exercise. Future directions include developing effective exercise recommendations for optimizing fat metabolism, thereby decreasing IMCL content and insulin resistance in overweight children.