A lot of people seem to agree that getting rid of grains (except maybe oat) is a good idea. A somewhat smaller group will agree that cutting down on carbs in general is a good idea. One version of this is the Paleo diet.
Then there's Caloric Restriction, which is what some people here do. I think most people would agree it's a healthy choice that will possibly lengthen one's lifespan, but it's impractical for them (counting calories, looking skinny, being hungry).
Another option is
Intermittent Fasting, which is what I do, and I know there's some other people here on this diet too. It's more about how you eat than what you eat, but combining it with a Paleo diet seems sensible, since IF is based on paleolithic eating patterns. Some studies suggest it's an alternative for CR, others say it won't increase lifespan.