Calorie restriction diets have received a lot of attention recently, and while they certainly have some drawbacks they are the most assured way for somebody to lose weight and stay slim – although most would probably consider it to leave you too slim.
A calorie restriction diet massively reduces your food intake so that instead of having the recommended 2000-2500 for those living an active lifestyle, you’re reduced down to about half that. This can be quite difficult to adapt to, but once you’ve done that you will be able to remain healthy enough to maintain that diet for years. In fact, one of the theorised affects of this type of diet is actually an extended lifespan, which comes about due to the massively reduced metabolism. This has been borne out in experiments on other animals, so if you are concerned about living a long time this might be a good option, and certainly less expensive than alternatives.