saturated fat, any solid fat that is an ester of glycerol and a saturated fatty acid. The molecules of a saturated fat have only single bonds between carbon atoms; if double bonds are present in the fatty acid portion of the molecule, the fat is said to be unsaturated. Unsaturated fats generally have lower melting points than saturated fats and are often liquids (oils) at room temperature. Unsaturated fats can be converted to saturated fats by a process called hydrogenation; since this usually raises the melting point of the fat and makes it a solid, the process is also called hardening. A correlation has been found between the consumption of solid fats in food and cholesterol levels in blood. Cholesterol forms arterial plaques that may lead to blockage of the arteries, i.e., atherosclerosis. Dietary guidelines in the United States call for reduced intake of saturated fat. See fats and oils.