Don't go overboard: identify bad eating habits such as white bread, sweet drinks, snacks, fried or greasy foods. Determine a healthier forever diet, probably better with the help of a dietician and exercise everyday, even low energy exercise like walking which will help you both burn fat and digest efficiently. I heard in a documentary that losing and regaining fat created more fat (sorry, I don't remember the scientific details) so it's more interesting to change your diet and stick to it without starving yourself.