Brown fat, also known as brown adipose tissue, is a type of body fat found in small amounts in adults. Its levels decrease naturally with aging.
This type of fat plays an important role in generating heat, helping regulate body temperature, and supporting basal metabolism. It is highly innervated, and its heat production increases in response to stress, exposure to cold, and stimulation from thyroid hormones.
Because of these functions, brown fat is essential for thermogenesis, the process of producing heat, which contributes to higher basal energy expenditure.