John, we're talking about the fat itself hurting, not the muscle underneath.
Originally posted by Wizard
It's not the fat, it's the extra water that is stored in your muscles (3-4 grams of water is stored in every gram of glycogen) and creates that feeling. First, you deplete your muscle glycogen stores by exercising and consuming a low-carbohydrate diet. This enhances the re-synthesis of glycogen. The body stores as much glycogen as it can to compensate for the low carbohydrate consumption levels. The muscles and liver overcompensate, storing levels higher than normal.