Quote by Tom Auditore de Firenze:
I agree! The idea is to burn more calories than you intake. Don't drop from a 2000 calorie a day diet to 500! Find a way to burn 1500 more calories a day. Your metabolism needs to "exercise." Your body doesn't want to eat itself and will slow your metabolism to stop it from happening. That's why people who starve themselves for months to lose 30 lbs. end up gaining twice that much back after they stop.
Cardio and a sensible diet are the way to go here. Swimming is a near perfect form of exercise. It works every area of your body including your heart, and burns a lot of calories without the impact of jogging or running.
Tom is spot on here. You need to train your body, not deteriorate it away.