Andrew HubermanEssentials: Cold & Heat Exposure for Metabolic Health | Dr. Susanna Søberg
Andrew Huberman
Cold must feel hard 0:00
A useful cold protocol should feel uncomfortable. Cold shock is the sign that the skin and body are getting enough of a stimulus. The breathing gets faster at first, and that gasping response is part of the early reaction. With repeated exposure, the response can ease. The point is not comfort. The point is to train adaptation so the shock becomes less severe over time.
Brown fat and heat balance 2:30
Cold water gives a stronger effect than cold air because it covers more skin and reaches the cold receptors more fully. Those receptors signal the hypothalamus, which helps control temperature. That sends out norepinephrine and helps switch on brown fat, a tissue that raises metabolism. Shivering also helps, and the two systems work together. Cold exposure can therefore act as a form of training for metabolism and insulin sensitivity.
Cold adapts brown fat 15:31
Sleeping one month in a 19° C room, even under a duvet and with clothes on, raised brown fat activity and insulin sensitivity. At 24° C the effect fell a little, and at 27° C it fell further. Cold seems to work quickly because brown fat responds to norepinephrine. It grows more mitochondria, takes up glucose and fatty acids, and helps clear sugar and fat from the blood.
Winter swimmers and dosing 21:01
In winter swimmers, one to two minutes in cold water, three dips, and two sauna rounds at about 80° C were enough to improve insulin sensitivity and glucose clearance. They produced less insulin and cleared blood sugar faster than controls. The study pointed to a low dose: about 11 minutes of cold and 57 minutes of sauna a week. More is not better, and overdoing it may exhaust cells.
Temperature as reset 31:00
Inflammation is linked here to depression, anxiety, and Alzheimer’s disease, so lowering it may help both body and mind. Cold and heat are described as natural stressors that bring the body back toward balance. Modern indoor, sedentary life has left people too temperature-comfortable, and that may help explain rising obesity and other lifestyle diseases.
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