The study of fat and its functions is an important medical trend in recent times. Even 25-30 years ago, fat was considered a passive tissue, which simply stores energy reserves, but in the early nineties, scientific works appeared that proved that adipose tissue is the most important endocrine organ. And of course, this triggered an avalanche of new research: pathophysiologists, biologists, and endocrinologists from all over the world began to study what fat is and how it affects the neuroendocrine system. Interest in the topic was also fueled by the fact that, according to the UN, up to a third of the world’s population suffers from some degree of obesity. Every one of these individuals is in danger for sicknesses that stoutness can incite, which implies that it is imperative to know however much as could reasonably be expected about the impact of adipose tissue on the development of any pathologies.
Adipose tissue is a type of connective tissue; it is made up of fat cells, or adipocytes, which store energy and secrete various substances, including hormones. This implies that fat tissue plays out a lot of errands in our body and it is generally because of it that it capacities as it ought to. The main function of fat is energy. Triglycerides, components of adipose tissue, when broken down, release a colossal amount of energy: twice as much as carbohydrates. The average adult has about fifteen kilograms of adipose tissue or about 110 thousand kilocalories. This reserve is enough to live for two months, burning 2 thousand kilocalories a day.
Another function of fat is thermal insulation. That is why the representatives of the northern peoples have a fat layer on average thicker than that of the southern ones. The next function of fat is supporting. This means that all our organs, such as the heart and even large vessels, are partially or completely surrounded by fatty tissue.
An important function of adipose tissue is regulatory. Fat cells are involved in hematopoiesis: they are part of the bone marrow, form the microenvironment of erythrocytes, leukocytes, and platelets, and provide them with nutrients while they develop. Another function is immune. The cells of our immune system have receptors that “read” the structures of dangerous microbes – in response, the system produces protective components, including cytokines and chemokines, which direct the process of fighting infection. Several years ago, the same receptors were found in fat cells.
Another unobvious function of fat is depositing: adipose tissue accumulates not only energy, but also some fat-soluble vitamins, and also serves as a large depot of steroid hormones, especially estrogens. Besides, it contains a supply of water (yes, not only in camels but also in humans), which means that a deficiency of adipose tissue will immediately lead, for example, to dehydration and aging of the skin. Both the lack of adipose tissue and its excess is equally dangerous for the body.
Now we finally come to the most interesting function of fat – the endocrine function. Present-day science believes fat tissue to be a different fringe endocrine organ. In women, it is, among other things, a source of an enzyme called aromatase, thanks to which our body synthesizes estrogens from androgens. Also, adipocytes from adipose tissue produce leptin, which is necessary for puberty and for maintaining reproductive function. By the way, in patients with amenorrhea, that is, the absence of menstruation, due to too strong physical exertion, the level of leptin falls, and its secretion is disrupted. And in normal women, serum leptin levels are 40% higher than in men.
Without adipose tissue, our body simply will not work: it is responsible for reproductive function and puberty, for immunity and hematopoiesis, it serves as fuel for basic metabolic processes, protects us from mechanical damage and hypothermia. Does this mean that the more fatty tissue in the body, the better? Of course not. Both the lack of adipose tissue and its excess is equally dangerous for the body. There are studies showing a direct link between an imbalance of adipose tissue in any direction and a decrease in life expectancy, so it is very important to monitor the percentage of adipose tissue in the body and how it is distributed.