What a gastric band does is reduce the size of your stomach, as Evian says. Then for the first 2 weeks after the op you can only consume a liquid diet which is things like slimfast, complan, soups without lumps etc and you eat whenever you feel hungry and stop the instant you feel full. After then you can eat puree consistancy food which is like blended foods, basically anything that doesn't need cutting with a knife and can be mashed with a fork. After that you are back on normal food. You take a multivit and get dietary advice on what food to eat so that you do lose the weight and don't make yourself ill in the process but other than that you take no medications unless you tell someone you have got one, no-one would know from the food you eat, it just forces you to eat much smaller portions of foods but is not as extreme as you may think.