I don't think we are 'designed' to eat meat in the quantities many people do. There's generally a neglect of fruit and veg, as well as cereals and pulses. Due to my own vegetarian fad of 26 years I am short, pasty and thin, as those who've met me will verify.
Josh was on a vegetarian diet until he was 2, when he expressed a wish to eat meat. To this day he has no problem eating fruit and veg, unlike the darling fussy eaters I've taken out with him.