Depending on the region in the body, differences in body fat distribution are more pronounced in one sex than in the other. On the one hand, women develop more subcutaneous (underneath the skin) fat and fat deposits than men. Some of the areas in a woman’s body where more fat is evident are the following:
· Breasts. More defined fat in this area protects the mammary glands, in preparation for milk production and storage;
· Hips and buttocks. More fat in this part protects the anal area and helps cushion the bones from the supporting surface (i.e., the seat) especially when a woman is pregnant;
· Others: the thighs and pubic area
A body type with more fat in the hips and thighs or the lower region of the body, which is characteristic of women, is known as the “gynoid” or “pear body type.” On the other hand, storage of more fat in the abdominal or upper region of the body, which is characteristic of men, is known as “android” or “apple body type.”
Aside from genetics and reproductive differences, the way the body utilizes fat also plays an important role in why fat deposition varies in both sexes. Some studies reveal that the way specific hormones stimulate the hormone responsible for initiating fat breakdown (i.e., lipase) dictates how fat is mobilized, metabolized, or stored in different parts of the body. For example, the hormone epinephrine, which is released by the nervous system during exercise, stimulates hormone-sensitive lipase (HSL). HSL then breaks down triglycerides in fat tissues and releases the component fatty acids and glycerol into the blood stream. Fatty acids and glycerol are then further broken down in cells and in the liver respectively, for energy production.
Meanwhile, another type of lipase, lipoprotein lipase (LPL), which is stored in large amounts in fat tissue and the liver, acts on triglycerides present in the blood stream. LPL breaks down the triglycerides into component fatty acids that are, more often than not, diffused into fat tissue depots or the liver, for re-synthesis into triglycerides and eventual storage.
Research has shown that in both men and women, abdominal fat is more receptive to epinephrine-induced fat breakdown than in the hips and thighs. Compared to men, however, women have more epinephrine receptors in the hip and thigh region that inhibit fat breakdown. In addition, women have more concentrations of LPL, and therefore more fat storage activities in the hips and thighs than in men. At the hormonal level, these are reasons why women store more fat in the lower region of the body than men.