11 minutes cold, 57 minutes heat: the weekly dose for metabolic health
Susanna Søberg's winter swimmer research, Huberman's cold and heat episodes and Rhonda Patrick converge on modest weekly doses of cold and sauna for brown fat, insulin sensitivity and heart health, ending on cold. It turns vague advice into a specific, achievable target.
You do not need hour-long ice baths or daily marathon sauna sessions. Roughly 11 minutes of cold and 57 minutes of sauna per week, spread over two to three days and always ending on cold, went with more active brown fat, lower fasting insulin and faster glucose clearance in one study. Those numbers are approximate minimums for metabolism, not ceilings.
The figures come from Dr. Susanna Søberg's study of Danish winter swimmers. On swimming days the men did up to three cold dips of up to two minutes and two sauna sessions at about 80°C for 10 to 15 minutes, starting and ending in cold water. Her message is that you do not need extremes, and that 20 to 30 minute ice swims can push the body toward chronic stress. She gives no target temperature. The goal is to get uncomfortably cold: "You should not enjoy it." Ending on cold forces the body to rewarm itself, which keeps brown fat and muscles working for hours.
Andrew Huberman adopted the numbers and calls them the Søberg protocol. He treats 11 minutes as a floor, split into two to four sessions of a few minutes, in water that is "uncomfortably cold but that you can stay in safely." For sauna he suggests 80 to 100°C for 5 to 20 minutes per session. He also recommends shivering on purpose to boost metabolism, and admits he takes a hot shower afterward himself, which gives up some of the metabolic benefit.
Rhonda Patrick never cites the 11 and 57 figures, but her account supports the same idea: short, repeated challenges switch on protective pathways. She explains how cold builds brown fat, and adds that this affects metabolism but will not replace diet and exercise for weight loss.
The main disagreement is about the heart. Finnish studies cited by Huberman and Patrick found that using a sauna four to seven times a week went with about 50% lower cardiovascular death than once a week, and that sessions over about 19 minutes drove the big effects. So 57 minutes a week is a metabolic minimum, not the heart-health optimum. They also differ on transitions: Patrick waits a few minutes between heat and cold after once becoming dizzy. On women, Huberman sees no reason the effects would be male-only, while Søberg, whose study included only men, is more cautious.
The article notes the evidence has limits. Søberg's study was a small, unfunded proof of concept in men, and the Finnish data are associations.
What to do with it: budget about 11 minutes of cold a week in short bouts and set the temperature by feel. Add about 57 minutes of sauna, starting low. Finish on cold and rewarm naturally. Immerse to the neck and move your limbs. Keep cold about four hours away from strength training, and do it early if you sleep poorly.
Stay safe. Never swim alone, respect hypothermia, take special care with children and never combine sauna with alcohol. People who are pregnant, nursing or heat sensitive should avoid saunas unless a doctor says otherwise. Anyone with a heart condition, blood pressure problems or other health concerns should get a doctor's advice before starting.