Food Pyramid is still the way to go with carb your staple food except that in Asia the amount of carb consumed, especially hawker food, is just too much while the amount of vegetable and fruit is much too little. For Westerners especially Americans, although the pyramid is more balanced, the overall quantity consumed is much in excess. Nutritionists recommend a balanced diet most of the time and in accordance to the food pyramid with slight adjustments to your condition. If you go on an extremely low carb diet to lose weight, despite your fat cells, you will still need to satisfy your energy requirement by eating more protein, either meat, fish or some bean stuff like tofu, which can also give some energy but not in as efficient a way as from carb. The problem with food substitution is that another organ is being called into the digestion process and could be overworked especially if an extreme diet is being followed.