Burning stored fat

Periodic fasting triggers the same fat-burning process that occurs during a low-carbohydrate or keto diet. Keto is short for ketosis, the metabolic process that kicks in when your body runs out of glucose (its preferred energy source) and starts burning stored fat. Your body may go into ketosis after just 12 hours of not eating, which many people do overnight before they “break fast” with a morning meal. (A midnight snack obviously sabotages this process.) A keto diet keeps you in ketosis for much longer time periods because you avoid carbohydrates, which supply glucose. Instead, fat becomes the preferred fuel source.

But some nutrition experts worry that keto diets — which typically include hefty amounts of meat and eggs — may be hard on the heart. Intermittent fasting is likely a healthier option, especially if you eat a balanced diet that includes whole grains, nuts, legumes, fruits, and vegetables, which are rich in nutrients known to lower heart disease risk.

Personally I feel that ketosis kicks in best after 36 hours of zero carbohydrates. Energy levels change dramatically as though new batteries have been put in. Speed of movement not quite at original tempos.