In the body, we distinguish between white fats and brown fats. These burn calories by producing heat to protect us from the cold.
brown adipose tissue is a type of fat found in the human body. Unlike white fat which stores energy, brown fat uses it to generate heat and regulate body temperature. Discovery of the role, production and mechanisms of brown fat in the body.
What is brown fat?
The human being has three types of so-called “adipose” fatty tissue composed of cells that store fat (adipocytes):
► The white fatmajority in the body. “The purpose of white fat is to store energy reserves” explains Dr. Pierre Nys endocrinologist-nutritionist. These reserves come from lipids provided by food. excess white fat is associated with obesity and cardiovascular disease. “When you have too much energy to store and the white adipocytes are full, you recruit other pre-adipocytes which become white storage adipocytes“says Dr. Pierre Nys endocrinologist-nutritionist.
► brown fat or brown adipose tissue is made up of brown adipocytes. “Brown fat expends energy and produces heat” continues our interlocutor. Brown adipose tissue is mainly present in fetus, infant and young children. “It is particularly concentrated in back, neck, shoulders, around the spine, heart and kidneys“ adds the endocrinologist. Brown fat decreases in adulthood in favor of white fat.
► beige grease. Under the effect of the cold, the cells of the white adipose tissue can turn brown. This is called beige adipose tissue.
White adipocytes have no major metabolic activity unlike brown fat, which is made up of triglycerides and many mitochondria. “The embryological origin is also different: brown adipocytes are probably close to muscle cells” emphasizes Dr. Nys. Lipids are stored as triglycerides in lipid droplets. White adipocytes contain a single lipid droplet while brown adipocytes contain many.
How is brown fat produced?
Brown fat is produced by prolonged exposure to low temperatures. “It is estimated that a exposure below 19 degrees several hours a day“specifies our interlocutor. To stimulate the production of brown adipose tissue, the only proven and effective solution is exposure to cold temperatures.”Studies have shown that people working in the North and South Poles have more brown fatty tissue than average. Otherwise, consuming green tea appears to increase the production of brown fat but this is not clearly demonstratednotes Dr. Nys.
What is the role of brown fat?
Brown adipocytes use the fatty acids (lipid stores) they contain to produce heat, in other words the brown fat helps warm the body. Brown adipocytes dissipate energy in the form of heat by burning calories through a process called non-shivering thermogenesis, as opposed to muscle-mediated chill thermogenesis. Brown adipose tissue thermogenesis is activated by the sympathetic nervous system (in the brain). “Brown fat in particular helps regulate the temperature in the newborn who is not shivering yet. In adulthood, brown adipose tissue participates in body thermal regulation during exposure to cold, but to a lesser extent since the muscles are capable of producing shivers to warm the body.” develops the endocrinologist.
Brown fat warms the body while white fat insulates it from the cold.
Does brown fat protect against the cold?
Brown fats are present in large quantities in infants precisely to warm him up since he is not yet able to shiver. They produce heat to protect it from the cold. At the house of the adultbrown adipose tissue (less present) participates in warm up the body when the thrill is not enough. “People with little brown fat shiver a lot, and people with a lot of brown fat shiver less” notes the expert. If brown fat heats up, white fat insulates the body against heat loss. It’s a real defense against the cold.
Child or adult: who has more brown fat?
Brown fat is very present in the fetus and newborn then is almost lost in adulthood. “The amount of brown adipose tissue is found in greater amounts in people whose occupation involves prolonged exposure to cold (cold room, poles, etc.))” emphasizes Dr. Nys. Furthermore, there is a correlation between the amount of brown adipose tissue and BCAA amino acids. “The more brown fat you have, the less BCAA amino acids you have. However, these are found to be high in people with obesity, diabetes or insulin resistance.“ indicates our interlocutor.
Thanks to Dr Pierre Nys endocrinologist-nutritionist.
Source: History and Cell Biology. Introduction to pathological anatomy. Abraham Kierszenbaum.2015