Fats are a source of energy in foods. They belong to a group of substances called lipids, and come in liquid or solid form. All fats are combinations of saturated and unsaturated fatty acids.

Fat is one of the three nutrients (along with protein and carbohydrates) that supply calories to the body. Fat provides nine calories per gram, more than twice the number provided by carbohydrates or protein.

Fat is essential for the proper functioning of the body. Fats provide essential fatty acids, which are not made by the body and must be obtained from food. The essential fatty acids are important for controlling inflammation, blood clotting, and brain development.

Fat serves as the storage substance for the body's extra calories. The body fills the fat cells (adipose tissue) that help insulate the body. Fats are also an important energy source. When the body has used up the calories from carbohydrates, which occurs after the first 20 minutes of exercise, it begins to depend on the calories from fat.

Healthy skin and hair are maintained by fat. Fat helps the body absorb and move the vitamins A, D, E, and K through the bloodstream.

Additional Resources:
http://edis.ifas.ufl.edu/he695