Evolution happily trades everything away that would allow to escape the niche your stuck in. And one day, you are a koala, unable to recognize leaves when they are not on branches, a planktonwhale beaching yourselves, a panda who needs electric help to procreate, or a sloth to slow and calorie low to eat. Moral of the story: High effort Low Energy diets are a evolutionary swamp - never eat all your veggies.