Whilst PET does show brown fat activity, it is subject to a number of limitations including the challenge of signal variability from a changing environmental temperature. (sciencedaily.com)
After this mild cold exposure, all ten volunteers with type 2 diabetes, as shown in that study, displayed increased brown fat activity and improved insulin sensitivity. (diabeticmediterraneandiet.com)
Thus, cold showers can promote brown fat activity. (medicaldaily.com)