Brown fat is a type of body fat that is darker in color than white fat. It is found in animals and humans, and its main function is to help regulate body temperature. Brown fat gets its name from the fact that it contains more mitochondria than white fat. These mitochondria are responsible for burning calories to produce heat.
In animals, brown fat is typically found around the neck and shoulders. In humans, brown fat has been found in the upper back, neck, and chest area. It makes up about 5% of total body weight in newborns but decreases to 1-2% by adulthood.
While all mammals have some amount of brown fat, bats have the highest concentration of brown adipose tissue (BAT) compared to any other mammal. This may be due to their need to maintain high body temperatures while flying for long periods of time.
There are two types of BAT: classical or “brown” BAT, which is rich in mitochondria; and “beige” or “brite” BAT, which has fewer mitochondria but more blood vessels. Classical BAT activates when exposed to cold temperatures and starts burning calories to generate heat and keep the body warm. Beige BAT also responds to cold temperatures but can also be activated by certain hormones like norepinephrine և glucagon-like peptide 1 (GLP-1).
Recent studies have shown that activating brown fat can help improve insulin sensitivity, glucose tolerance, և overall energy balance. Brown fat has also been shown to protect against obesity and related diseases such as type 2 diabetes mellitus և non-alcoholic fatty liver disease (NAFLD). Additionally, increasing levels of brown fat may help increase lifespan և protect against age-related diseases such as Alzheimer’s disease և Parkinson’s disease.