Cold acclimation recruits human brown fat and increases metabolic rate

Researchers studied 15 healthy, lean men before and after 10 days of mild cold exposure. They spent several hours each day in a cool room, around 15°C, or 59°F. The researchers used scans to measure brown fat, a type of body fat that produces heat, and measured how much energy the men burned at rest. After the cold exposure, the men had more active brown fat and burned somewhat more energy, but they did not lose meaningful weight.

What this means for you: This suggests repeated mild cold can temporarily increase brown-fat activity and energy use. It is a small, short study in lean men, so it does not show that cold exposure is a useful or safe weight-loss treatment for most people.