The faulty thought process of depriving oneself of carbohydrates is that if the body cannot use them for fuel, then it will naturally burn fat. However, fat is an extremely efficient fuel source and provides more than twice as many calories per gram as carbohydrates and proteins. When your body does not receive enough carbohydrates, it essentially kicks into a “survival mode”. If all it has to choose from for fuel is protein or fat, what do you think its instinct will be? It will hold onto the fat because it can last twice as long (due to the larger amount of energy or calories received from fat) and start to burn muscle for fuel. This defeats the purpose and lowers your lean tissue mass, thus contributing to slowing your metabolism.