Along with protein and carbohydrate, fat is a food element that is essential to the human diet. The fats that we get in our food, such as animal fats (including butter and cream) and vegetable fats, are digested mainly in the small intestine. There they are broken down into fatty acids and glycerin. After these fat products pass through the intestinal wall, they again form fat. The fat reaches the tissues of the body by way of the lymphatic system and also the blood vessels.
Every tissue in the body has some fat. However, when there is an excess of fat, it accumulates most readily just underneath the skin, around the kidneys, and in the liver.
The fat of our bodies is formed not only from the fat in the foods we eat but also from the carbohydrate and protein. When more than enough of these elements are eaten than are needed for energy, they are changed into fat and stored.
