A major source of energy in the diet. All food fats have 9 calories per gram. Fat helps the body absorb fat-soluble vitamins, such as vitamins A, D, E, and K, and carotenoids. Some kinds of fats, especially saturated fats and trans fats (see definitions), may raise blood cholesterol and increase the risk for heart disease. Other fats, such as unsaturated fats (see definition), do not raise blood cholesterol. Fats that are in foods are combinations of monounsaturated, polyunsaturated, and saturated fatty acids.