Your brain, not your white blood cells, keeps you warm, new study suggests
The sympathetic nervous system, not white blood cells, are critically important in the regulation of energy expenditure and thermogenesis, researchers reveal in a new report. Ref. Source 8j.
Of course it is the brain the regulates this. As you get cold you brain will have your blood vessels enlarge some to get more heat down to the cold areas to help warm them up or shrink some to restrict if too hot. If you are cold it will cause you to shiver as that helps the body to produce heat. Plus your body will burn more calories trying to keep you warm than it does if you are too hot. If you are hot it will expend energy to sweat liquid out so that your body can cool off during the evaporation stage.