Drink no liquid that isn’t at least a thousand years old (wine, water, coffee). Eat nothing invented or re-engineered by humans.
When consuming plants they would have been regular, meat irregular, so it would make sense to eat mostly plant based most of the time then feast on meat intermittently.
In nature, we had to expend energy to eat. Lions do not eat then hunt for fun. Fasting is quite good for us, and natural. We do not need to load up on food before doing something, rather, re-feed after.