Treatment schemes for cold- and mirabegron-stimulated BAT activation. (A) Flow diagrams outlining the study design. All healthy volunteers (n = 14) were subjected to mirabegron treatment daily for 27 days. A subset of these volunteers (n = 8) were subjected to cold exposure 2 days prior to initiation of mirabegron treatment. (B) For the cold exposure protocol, blood was drawn from subjects prior to entering a metabolic chamber. After 4 hours, the subjects were exposed to cold using a cooling vest and blood was additionally drawn after 1 hour. For mirabegron treatment, subjects completed a dual-energy x-ray absorptiometry scan and then entered the metabolic chamber on Day 3 or 29 for a total of 20 hours, during which blood was drawn prior to and post mirabegron treatment. Mirabegron treatment continued for 27 days.