Just skipping one meal is bad for you, so not eating at all for a week is a very bad idea. Like crisgal says, your body would go into starvation mode, so when you do eat again your body would store extra fat, as it is preparing itself for the possibility of not getting more food for a while, and surviving on what fat you have. When david small describes getting the shakes, his blood sugar levels where probably dangerously low. If this happens there is a possibility of you fainting, or worst case scenario falling into a coma. If we were meant to skip meals we would probably have a big hump on our backs like camels!
Your body tells you it�s hungry for a reason. If your car was out of petrol you�d fill it up � same goes for your body � food is your fuel, you can�t expect to function properly without it.