Ray Peat on fasting, fats, and stress. “When we don’t eat for many hours, our glycogen stores decrease, and adrenaline secretion is increased, liberating more glucose as long as glycogen is available, but also liberating fatty acids from the fatty tissues. When the diet has chronically contained more polyunsaturated fats than can be oxidized immediately or detoxified by the liver, the fat stores will contain a disproportionate amount of them, since fat cells preferentially oxidize saturated fats for their own energy, and the greater water solubility of the PUFA causes them to be preferentially released into the bloodstream during stress. In good health, especially in children, the stress hormones are produced only in the amount needed, because of negative feedback from the free saturated fatty acids, which inhibit the production of adrenalin and adrenal steroids, and eating protein and carbohydrate will quickly end the stress. But when the fat stores contain mainly PUFA, the free fatty acids in the serum will be mostly linoleic acid and arachidonic acid, and smaller amounts of other unsaturated fatty acids. These PUFA stimulate the stress hormones, ACTH, cortisol, adrenaline, glucagon, and prolactin, which increase lipolysis, producing more fatty acids in a vicious circle. In the relative absence of PUFA, the stress reaction is self limiting, but under the influence of PUFA, the stress response becomes self-amplifying.” Glycogen = Stored form of glucose in liver and muscles. Adrenaline = Hormone that increases heart rate and energy. Lipolysis = Breakdown of stored fat into fatty acids. PUFA = Fats with multiple double bonds, often found in vegetable oils. Saturated fats = Fats with no double bonds, solid at room temperature. Free fatty acids = Fatty acids released into the blood. Linoleic acid = Common omega-6 fatty acid found in seed oils. Arachidonic acid = Omega-6 fatty acid involved in inflammation. ACTH = Hormone that signals adrenal glands to release cortisol. Cortisol = Stress hormone that raises blood sugar. Glucagon = Stress hormone that raises blood sugar.