The majority of stored fat on the human body is present under the skin, or as subcutaneous body fat. This fat tissue is made up of fat cells. A human can have anywhere between 50 – 200 billion fat cells distributed around the body. We also store fat in other areas around the body, but this is dependent on the sex of the person. For most females, a high percentage of the subcutaneous adipose (fat) tissue surrounds the areas of the breasts, waist, hips and buttocks. Most males have a high percentage of their subcutaneous fat distributed around the fat areas of the chest, abdomen and buttocks regions.

There is also fat storage around the kidneys, liver and even inside muscle. In fact, as we age, fat storage within muscle tends to increase and means we don’t notice an increase in this area like we do when it’s placed around the waist. If activity levels drop its possible that muscle shrinks and fat replaces it, the result is we lose strength with age but muscle volume increases because fat is less dense than muscle and thus occupies more space.

How fat is stored
The sole purpose of a fat cell is to store small droplets of fat molecules. These fat molecules are formed as the concentrations of fatty acids in the blood rises, such as after a big meal. An increase in concentrations within the blood triggers lipase enzymes located in fat tissue, to grab the fatty acids and convert them into a fat molecule (triacylglycerols) for storage.

In fact, as we gain weight and become fatter, the fat cell numbers do not multiply, rather they just store more fat molecules, thus they expand to become larger. Fat cells in the human can multiply, but only if fat storage cells “run out”.