The most concentrated stored energy in food. Each gram (g) supplies 9 calories of energy. Fats are digested to fatty acid and glycerol molecules and serve as a carrier to absorb the fat-soluble vitamins A, D, E, and K into the body from the gut. Fatty acids are building blocks of membranes and play a key role in numerous body functions.
Two fatty acids that the body requires, but cannot make, are omega-3 and omega-6 polyunsaturated (PUFA) fatty acids. These two PUFAs oppose and balance each other in vital body functions such as blood clotting and inflammation. They make up 30% of eye retina and 15% of brain structure and are required for their function.
Omega-3 fatty acids are linolenic acid, derived from plants, and eicosapentaenoic acid (EPA) and docosa-hexaenoic acid (DHA), which are derived mainly from fish.
In the body, excess calories are stored as fat, providing a reserve supply of energy.