If the body can do this clease without any energy input. WHY DOESNT IT DO IT AROUND THE CLOCK?

Autophagy can not occur when your insulin levels are elevated.

Insulin is what tells your body it's time to burn carbohydrates for fuel and to store any extra calories as fat to be used by your body at a later time.

Once your insulin levels drop down to baseline, your body begins using ketones from fat as fuel and begins repairing the cells.