Dr. Melanson is a Professor in the School of Medicine at the University of Colorado Anschutz Medical Campus. His research is focused on studying the effects of lifestyle factors (physical activity, diet, and sleep) on bioenergetics (energy and substrate metabolism, and physical activity), particularly related to obesity and aging. Dr. Melanson has made substantial contributions in several areas of related research. He has used whole-room calorimetry to determine how exercise intensity, aging, and obesity affect substrate oxidation at the whole-body level. He has also measured skeletal muscle oxidative capacity to determine its association with substrate oxidation measured at the whole-body level. In these studies, he has demonstrated how 24 h fat oxidation is primarily determined by overall energy balance, rather than exercise type or intensity, and that this is also observed in overweight and older adults. With his long-time collaborator Dr. Kenneth Wright, an expert in sleep physiology from the University of Colorado Boulder, Dr. Melanson has also performed studies to determine the effects of sleep restriction and alterations in normal sleep-wake cycles (e.g., simulated night shift work) on energy expenditure, substrate oxidation, and energy intake. These studies have shown that alterations in normal sleep patterns disrupt both energy expenditure and energy intake, leading to positive energy and fat balance, thereby increasing the risk of weight gain. Collectively, these studies have enhanced our understanding of how different lifestyle factors impact bioenergetic responses and the maintainance of energy and substrate balance. Currently, members of Dr. Melanson’s lab are conducting studies to understand how certain lifestyle factors (sleep, physical activity, and timing of meals) interact to affect metabolism. Dr. Melanson has also performed collaborative research with Dr. Wendy Kohrt, the Nancy Anschutz Chair in Women’s Health Research at the University of Colorado Anschutz Medical Campus, to understand how the menopausal transition, and in particular estrogen status, impacts energy expenditure and physical activity. These studies have shown that suppression of estrogen in women leads to reductions in energy expenditure and physical activity, and that some of these effects can be reversed by estrogen add back therapy. This collaborative effort spawned a new area of research for Dr. Melanson, and in 2017 he received an NIH R01 award to study the effects of estrogen on brown fat activity. In these studies, he is using dynamic PET/CT imaging to determine how estrogen status impacts brown fat activity. It is expected that these studies will contribute to our understanding of how the menopause transition impacts energy metabolism and increases the risk for fat gain.
Dr. Melanson has maintained an interest in developing and validating objective methods for measuring physical activity and energy expenditure in free-living humans, and this remains an area of focus for his group. These studies include novel instrumentation, such as measures of heat flux as a means of measuring energy expenditure, and validation of a laser-based instrument to measure isotopic enrichments in urine samples, specifically when applied to the doubly labeled water method for measuring free-living total daily energy expenditure. Dr. Melanson’s lab has recently shown that this approach produces measurements of total daily energy expenditure with accuracy and precision similar to isotope ratio mass spectrometry. Currently, Dr. Melanson’s groups is exploring measurements of isotopic enrichments with the doubly labeled water method in both saliva and breath. This work has the potential to reduce the analytical costs associated with the doubly labeled water method to measure energy expenditure in free-living humans.