Resting Metabolic Rate (RMR) is a form of metabolism measurement that measures the amount of energy used by the bodies of animals in a relaxed, but not post-absorptive, state.RMR measurements require the animals be in a thermal neutral zone (or a preferred temperature range for bradymetabolic animals) and relaxed.esting Metabolic Rate (RMR) is a form of metabolism measurement that measures the amount of energy used by the bodies of animals in a relaxed, but not post-absorptive, state.