Periodic fasting can better match your diet to human evolution. When fasting the body enters ketosis. During ketosis, the glucose we normally get from carbs is manufactured from fat. We change from a carb-burning machine to a fat-burning machine. Ideal for reducing body fat.
However, fasting is best done when the body is already in ketosis to minimize strength loss. So long as you supplement with essential amino acids no harm will result. For example a light meat/vegetable broth supplement rather than a strict fast. see: fasting linked less severe covid study