I do not quite agree with the previous speaker: the number of adipocytes in humans is laid at a young age and can not be the same in people with different constitutions.
In addition, it is true that the number of adipocytes almost does not change during life ... A reduction in their number is possible only with long-term (several years) maintenance of weight different from what was in adolescence.
We have a special type of connective tissue - adipose tissue, it consists of adipocytes. These cells are incapable of reproduction, because their number in the body is the same in both a full and a thin person. Only the shape of the adipocyte itself changes. As long as it is low in lipids, that is, fats, it has the form of a small spindle-shaped cell. As soon as fat begins to accumulate in it, it stretches to a solid ball size, in which the absolute majority of the space is occupied by a fat drop.
Lipids are synthesized in the adipose tissue itself from the breakdown products of fats and carbohydrates received from food.