Brown Fat Activation Mediates Cold-Induced Thermogenesis in Adult Humans in Response to a Mild Decrease in Ambient Temperature

Context: The contribution of brown adipose tissue (BAT) to the energy balance in humans exposed to sustainable cold has not been completely established, partially because of measurement limitations of both BAT activity and energy expenditure (EE). Objective: The objective of the study was to characterize the role of BAT activation in cold-induced thermogenesis (CIT). Design: This study was a single-blind, randomized crossover intervention. Setting: The study was conducted at the National Institutes of Health Clinical Center. Study Participants: Thirty-one healthy volunteers participated in the study. Interventions: The intervention included mild cold exposure. Main Outcomes: CIT and BAT activation were the main outcomes in this study. Methods: Overnight EE measurement by whole-room indirect calorimeter at 24°C or 19°C was followed by 2-[18F]-fluoro-2-deoxy-D-glucose positron emission tomography (PET) scan. After 36 hours, volunteers crossed over to the alternate study temperature under identical condition...