In addition to providing energy, fats are essential for the functioning and structure of body tissues (Table 5-1). Fats are a necessary part of cell membranes (cell walls). They contain essential fatty acids and act as carriers for fat-soluble vitamins A, D, E, and K. The fat stored in body tissues provides energy when one cannot eat, as may occur during some illness and after abdominal surgery. Adipose (fatty) tissue protects organs and bones from injury by serving as protective padding and support. Body fat also serves as insulation from cold. In addition, fats provide a feeling of satiety (satisfaction) after meals. This is due partly to the flavor fats give other foods and partly to their slow rate of digestion, which delays hunger.