What is brown fat? What functions does it perform? We will answer these and other questions in the article. There are two types of fatty substance in the human body: brown (BAT - provides thermogenesis and creates heat by burning fat) and white (WAT - designed to store energy). Obese people tend to have less brown fat and more white fat.
Function
Brown fat allows the body to maintain a constant temperature. This mechanism is called thermogenesis. There are two types of thermogenesis: contractile (chilling), in which heat is generated due to contraction of skeletal muscles (a common occurrence is muscle cold shivering), and non-contractile (brown fat activity).
To effectively fight some ailments, the human body independently raises the temperature. If someone suffers from a fever, his thermoregulatory system quickly reorganizes, activates and begins to operate at a higher level. That is why body temperature up to 38.5 degrees cannot be brought downworth it.
Anatomy
The earliest brown fat was found in animals. In those animals that hibernate in winter, this substance is best developed, since during this period the metabolism slows down. In view of this, it is impossible to maintain body temperature with muscle contractions.
Brown fat is also important when animals wake up in the spring: with the help of the heat it generates, the body temperature increases significantly, causing the animal to wake up.
Owners
Most recently it became known that only children have brown fat. It helps them get used to the new environment after they are born. In newborns, this substance is located in the kidneys, neck, along the upper back, on the shoulders, and makes up about 5% of body weight.
Also in the body of babies sometimes brown fat is mixed with white. For babies, brown substance is of great importance, as it protects them from hypothermia, due to which premature babies often die. Thanks to this component, newborns are less sensitive to cold than older people.
Brown fat cells have a unique quality - they contain a huge number of mitochondria (organelles that contribute to the accumulation of energy). Thanks to them, they, in essence, have their own color. Mitochondria contain a specific protein UCP1, which, bypassing the stage of ATP synthesis, instantly transforms fatty acids into heat.
Triglycerides (lipids) present in fat are the material from whichheat (ATP) can be produced. When an infant needs a lot of energy (for example, to keep warm), fats undergo lipolysis. As a result, fatty acids appear, which UCP1 in brown fat cells transforms into heat. As a result, there is a decrease in the stock of body fat. First, triglycerides are consumed in the brown substance, and when the lipid reserves begin to melt, then in the hateful white.
As a result, the body reduces its weight. However, for the process to be effective, a baby born into the world must eat well (energy is needed to activate lipolysis) and breathe normally (oxygen is required for the transformation of fatty acids).
Unfortunately, in an adult, this mechanism is gradually weakening. Already a couple of weeks after birth, shivering (a reaction to hypothermia) replaces the action of the brown substance, especially if babies are warmly dressed and kept in a hot room.
Adults
Today it was discovered that adult human has brown fat. For a long time it was believed that this substance loses its significance by the end of the first year of human life. However, in 2008, experts determined that brown adipose tissue not only resides in the body of adults (this became known back in 1908), but is also activated by cold.
This discovery was made using a new technology for imaging active metabolism in tissue. Positron emission and computed tomography were used, which showed that in the body of an adult individual there is about 20-30 grams (so little) of brown functional fat, mainly in the supraclavicular zone.
PET-CT is known to capture tissue metabolic activity. Physiologist Wouter van Marken Lichtenbelt reported that a group of young people (24 people) were given an accurate dose of radioactive glucose. This was done in order to further be able to detect active brown fat using a specific device.
After that, the study participants were taken to a room where the temperature did not exceed 16 degrees. CT-scans showed that under the skin of the chest, neck and abdomen of 23 people there is fatty “useful” tissue that works by warming people in a cold room.
The physiologist said that the experts were very surprised to see that there is so much of it and in such a large number of people. When three participants were examined at room temperature, no brown substance was found. Experts believe that the fabric has not disappeared, but simply stopped working.
Efficiency
So you know where brown fat is in a person. It is equal to no more than 1-2% of body weight. And yet, when the sympathetic nervous system stimulates this tissue in supercooled, cold-accustomed mammals, it increases its heat production. The energy generated in this way can reach one third of all additional heat created in the body. When activated, brown fat expends up to 300 watts (some say 400 watts) per kilogram of adult weight.
It is known that a person of average weight at rest burns approximately 1 kW of energy. By activating brown fat, you can lie on the bed and expend twenty times more energy than before.
Fat Burning
What is the function of brown fat? It helps to eliminate fat. If activated, fatty acids from white adipose tissue are pumped into brown adipose tissue. A white substance is deposited in the capsules and omentums of the internal organs, under the skin. Buraya, instead of accumulating energy, burns it in huge quantities. As a result, heat is released. This process is called thermogenesis, which begins its work due to excess food intake.
Conclusions
White and brown fat are two different substances. The oxidizing power of brown matter is 20 times greater than that of white matter. In brown tissue, during thermogenesis, the thermogenin protein acts, which contributes to the uncoupling of respiration and oxidative phosphorylation.
So we figured out what brown fat is. How to increase its amount in the human body in order to effectively fight obesity? To solve this problem, scientists use not only drugs, but also surgical means: with the help of liposuction, they extract ordinary white fat, transform it into brown, and implant it again in a person.
Theoretically, in order to lose weight, you need to either increase the activity of the brown substance at normal temperature, or increase its amount, or do both.
US Diabetes Association experts believe that brown fat contains very important reserves for patients suffering fromdiabetes and obesity. It is also known that in a fat person, the activity of brown fat is suppressed, and its amount is reduced. Therefore, in the near future, new drug and other methods of accumulation and activation of this “useful” substance in adults may appear.
