Impact of Weight Loss on Mitochondrial Function

Loss of body weight can elicit an adaptive decline in energy expenditure during rest and physical activity beyond what is expected based on the loss of metabolically active tissue, a phenomenon termed metabolic adaptation. The weight loss-induced decrease in energy expenditure (i.e., altered energy efficiency) can hinder continued weight loss and contributes to variation in weight loss success. The molecular mechanisms responsible for metabolic adaption include changes to sympathetic nervous system activity, decreases in leptin and thyroid hormones, and increases in skeletal muscle mitochondrial efficiency and capacity, though the dominant mechanism for metabolic adaptation is unclear. We have recently shown, using near-infrared spectroscopy (NIRS) technology, that we can non-invasively assess skeletal muscle mitochondrial efficiency (i.e., oxygen consumption rate) and capacity. The purpose of this study is to evaluate the association between skeletal muscle mitochondrial efficiency and capacity after weight loss with metabolic adaption and weight loss variability. To accomplish this aim, we will recruit individuals with obesity who have elected for bariatric surgery at local bariatric centers. We will assess their energy expenditure and mitochondrial efficiency and capacity before and after weight loss.