Fasting benefits by the body through a cessation of dietary toxins, including intestinal irritants such as fiber and starch, as well as unsaturated fats, particularly polyunsaturated fatty acids (PUFA).
Our bodies burn saturated fat for energy and store toxic PUFA, so as we age, PUFA accumulates. When stressed and without adequate sugars, the body raises levels of free fatty acids in the blood and burns these in place of carbohydrate in a process called the Randle cycle.
Stored PUFA inhibits the body’s ability to burn sugar and shifts the Randle cycle toward fat burning. While saturated fat substitutes as decent fuel, any burned PUFA damages the cell’s ability to burn sugar and increases the level of fatty acids further. With escalating fatty acid levels, a person continuously eats to stop the stress. Sugar, protein, and saturated fat opposes stress in the short-term, but any consumed PUFA stores in the body and, as more accumulates, the stress response amplifies in degree and duration at every point of activation.
Fasting deprives our body of sugars and increases stress. Within a day of going without carbohydrate, the adrenal glands, located just above the kidneys secrete epinephrine (adrenaline), which initially breaks down stored sugars in the liver for energy. After depletion of sugar in the liver, adrenaline shifts the metabolism of the body toward burning stored fats including the toxic PUFA, which causes damage throughout the body. Within a few days of consuming little carbohydrate, the body elevates cortisol levels, which further shift the body’s metabolism toward fat burning and thus greater reliance on the free fatty acids for energy. If the diet contains no carbohydrate for several days, the body begins its entry into ketosis, or the stage at which the body shifts toward its use of ketones,
and Within a few days, stored sugar in the liver depletes, and the body burns stored fat as fuel. Muscles burn fat at rest as well as under stress, so larger muscles tends to slow the accumulation of PUFA over time. The brain normally burns sugar for energy, but it can use another fuel type called ketones. When starved of sugars and without too much protein, the body takes 1 to 2 weeks to efficiently produce ketones. Since burning PUFA for energy damages the tissues, and since the brain requires so much energy, naturally any PUFA used as fuel would severely damage the nerves over time. Instead, the body minimizes its use of fatty acids as fuel and instead prefers sugar, or when starved of sugar, it the body produces ketones.
Ketone production stresses the liver, and the ketones themselves have stressful effects. Fruit and potatoes supply ketones without stressing the liver. One type of ketone, acetoacetate promotes tumor growth.
Prevention of Dietary-Fat-Fueled Ketogenesis Attenuates BRAF V600E Tumor Growth