Water only fasting

Bill Faloon (and others) are a fan of calorie restriction but as Aubrey De Grey has mentioned our best research and finally well established that long term restriction does not have the effect in long lived animals such as humans as it does in short lived animals. It does have the benefit that you're not over consuming calories however. 

Instead a better approach has been shown which is short term (3 days-3 weeks) water only fasting. For the research on this study Dr Victor Longo @UCLA. The link goes to his popular press book which espouses a 'fasting mimicking diet' which he developed for people (most) who don't like to fast. He studies centenarians and started his career being mentored by Roy Walford, who was the first to popularize calorie restriction, so you can see the lineage of this research and thinking. Rather than spout reams of research as to all the benefits (hint, think mTor without taking drugs, destroying senescent cells and immune cells - and regenerating them within three weeks after the fast), but you can start your research with Longo. 

Personally I have done 'professional' fasting regimes at the True North Health center in Santa Rosa, CA. I can recommend them if you're getting started. Or you can just do it at home. Unless you have a serious condition and are otherwise healthy 3-6 days is optimal. Personally I do two a year, one going into New Years and also in July, for six days each. 

It's not pleasant, but it does have a certain 'nuministic' aspect (spiritual if you like), as your mind goes all sorts of interesting places. Physically it's like having the flu for a week, and rather like being reborn when you refeed. 

Simple, natural, free (saves you money on food!), scientifically established and has a long established cultural precedent. And if you think about it from an evolutionary standpoint, makes a lot of sense.