Keto Last Card Just doing your very day routine is now burning fat now. How this happens is when the liver is deprived of carbs it produces ketons (a by-product of fatty acids). Now on Friday afternoon a couple of hours before your workout you are going to cut the fat way back and start loading up on carbs until Saturday at midnight or when you go to bed. What this does is restore the glycogen to the muscles. We need the glycogen in the muscles to get us through our workouts.