All I know is that I've made some big screw-ups, and I've done some things that have done all right. I just keep trying to learn from the mistakes I've made.
I tried the paleo diet, which is the caveman diet - lots of meat. And I tried the calorie restriction diet: The idea is that if you eat very, very little - if you're on the verge of starvation, you will live a very long time, whether or not you want to, of course.