Food that's heated over a fire is easier to digest and less likely to make you painfully ill — which is why cooking our meals has been considered healthier for millennia. But the growing raw food movement purports to offer healthier alternatives with food that's untouched by heat. Now it turns out that raw food may have unexpected drawbacks. New research suggests that cooking affects how much energy we get out of our food.

Researchers fed mice diets of sweet potatoes and meat, and varied the way the foodstuffs were prepared. What they found is that by cooking tubers and flesh, animals actually gain a significantly higher amount of energy from it, and the mice fed on cooked food got fatter.

This proves to be interesting from both pre-historical and modern perspectives. The advent of cooking meant that early humans could get a higher calorie surplus from foods, which gave them more energy to grow and expand. On the flip side, for modern humans it explains why raw/paleo diets can be effective. It also raises an interesting question about how calories are calculated, and if they're actually the same for raw and processed foods, regardless of what it says on the package.