Brown fat is active adipose tissue with more blood vessels and a busier metabolism than white adipose tissue. Brown fat is able to produce heat and consume energy instead of storing it. The main function of brown fat is thermogenesis.
Cold exposure is one of the most effective means of activating brown – or more correctly beige when inactive – fat, and regular cold exposure is a very effective means of activating brown fat. Active brown fat consumes energy and is able to remove excess fat from the bloodstream. There’s only about 60–100 grams of brown fat in an adult’s body, but tissue activation is estimated to burn the same amount of energy as one or two kilograms of fat per year.
Brown fat can protect against obesity, fatty organs and type 2 diabetes, which has become a national disease in Finland. Therefore, regular cold exposure in a controlled, easy-to-use cold pool can provide health benefits for many people.
For diabetics, brown fat and increasing its activity in the body can be significantly helpful because brown fat removes cholesterol and fatty acids from the blood. In addition, as insulin-sensitive tissue, brown fat improves glycemic control. The low level of brown fat may be one of the risk factors for type 2 diabetes based on the assumption that weight control will be facilitated by active brown fat.
Studies have shown that in overweight people, brown fat metabolism is not increased in cold or with insulin as much as for people who are normal weight. Therefore, actual weight loss must be carried out by conventional means, but activating brown fat in a cold pool, for example, can help maintain the weight loss results and ensure more long-term weight control.
The activation of brown fat lasts as long as the cold exposure, but ice swimmers, for example, have very active brown fat, even though they are in the icy water for only a short time. The increase in total energy consumption caused by cold is 10% higher for those with active brown fat. In a normal-weight person, acute cold exposure doubles the use of brown fat glucose, doubles blood flow and oxygen consumption, and approximately triples fatty acid consumption. The metabolism of functional brown fat increases several times as a result of cold exposure.