Interestingly, the people of the few mammals that are born with fatty deposits. They begin to appear at 30 weeks of fetal development. It used to be that people are born with already prepared by fat cells, and their number in the adult population is not increasing. At the present time to find out that it is not. Indeed, mature fat cells themselves are not divided, but throughout the life of human progenitor cells stored fat cells.
There are two periods of active reproduction of these precursor cells, and consequently, increasing the number of adipocytes: during embryonic development during puberty.
In other periods of human life are usually breeding progenitor cells does not occur. Fat accumulation occurs only by increasing the size of existing fat cells. This growth in adipose tissue is hypertrophic. However, no cell can not grow indefinitely. When the amount of fat in the cell reaches a critical mass of the progenitor cells receive the signal and begin to proliferate, giving rise to new fat cells. This type of growth of adipose tissue by increasing the number of fat cells, called hyperplastic (gipertsellyulyarnym). It can occur at any age.
So, lean adult has about 35 billion fat cells. A person who has expressed obesity, the number of fat cells may reach 125 billion, that is 4 times larger. The newly formed fat cells are not subject to back development, and preserved for a lifetime. If a person loses weight, they will only be reduced in size.