Also it assumes the increase in consumption from needing more calories will be uniform when my guess is it's not. Most people would have two servings of meat a day as a base augmented by a bunch of starches, sugars and fats to cover most of the calories, and any increases would probably be snacks of those starches and sugars that are way less co2 per calorie. If your diet is a stereotypical cheeseburger and fries, and your still hungry, your probably not gonna order another 1/4 cheeseburger and 1/4 fries, you'll probably just get another order of fries.