Definition: Fat is a major source of energy in the diet. Dietary fat contains nine calories per gram, which is more than twice the number provided by carbohydrates or protein. Due to its high caloric content, the chance of becoming obese increases with a high intake of fat.
Some fat is essential to proper body function. Fat fills adipose tissue that helps to insulate the body. Fat helps the body absorb certain vitamins. Healthy skin and hair are also maintained by fat.
Some types of fat (saturated and trans fats) raise blood cholesterol and can increase heart disease risk. A diet high in saturated fat causes cholesterol to build up in the arteries. Unsaturated fats do not raise blood cholesterol and they may help to lower cholesterol if used in place of saturated fats.
Examples: Fat helps the body absorb fat-soluble vitamins, such as vitamin A.