Project Summary/Abstract We are proposing to purchase a new indirect calorimetry system, Promethion-Core metabolic phenotyping system, which is a robust and versatile platform for researcher groups who are working towards gaining a greater understanding of molecular mechanisms controlling energy balance and body weight regulation. It is the most sophisticated and sensitive instrument in the market that simultaneously quantify multiple parameters including oxygen consumption, carbon dioxide production, energy expenditure, substrate utilization, food and water intake, and spontaneous activity. The new Promethion-Core system would provide sixteen individual home cages at a time, that can do a continuous sampling of all parameters to ensure accuracy and scientific rigor. A chamber for modulating the environment, including humidity, barometric pressure, temperature, light, occupancy, and sound is also included. This would provide a marked upgrade over the existing system in our UofU-MPC (the University of Utah Metabolic Phenotyping Core). It will be extensively used by more than 18 NIH-funded research groups in UofU to capture synchronized metabolic and behavioral information which can generate valuable insights into the understanding of molecular pathways important in the regulation of energy balance and behavior.