Pure Keto Cleanse Can we then perhaps do something ourselves to stimulate or increase the brown fatty tissue? The answer is yes: suffering cold . Lumberjacks in northern Finland work much below zero for much of the year, and they have significantly more brown fat than people who work indoors.Suffering a cold really means being cold. So if you set the thermostat to zero in the winter at home, you are not allowed to wear a thick sweater and warm slippers. And go outside in a summer outfit. Because only when your body temperature starts to fall below a certain level will the brown fat cells start burning fat.