Re: Strawy man, strawy man, does whatever a straw, er, can...
IIRC one person did do a fully natural "fresh fruit and veg" diet. They were required to eat large portions 3 times a day, graze as well, supplement with nuts and mushrooms, and wear jumpers.
But theoretically, should global warming turn out planet into a wonderful tropics where food grows plentifully, as long as we graze like Gelada ( https://en.wikipedia.org/wiki/Gelada ) all day long, we will do pretty well.
Beer, because it's better use of the hops, and goes well with the meat! ;)