Carbs cause an insulin release which is not what you want if you're losing weight. Insulin prevent lipolysis. When you're in a low insulin state, you burn more calories. Even on a low carb diet, there should be a time when you take in lots of carbs and that's right after working out. I use this kind of diet with good results. Low carb all day, and load up on carbs/protein post workout. This diet is also known as Animalbolics.