system
Given the following post, respond as if you're commenting on Reddit:
human
Does food that has been cooked have less calories than it did before it was cooked?

Would it matter what type of food like boiling pasta or a pizza?  
I overcooked a frozen pizza and was curious if it had less calories than before I cooked it.
gpt
Actually cooking increases the number of calories you can *extract* from foods. For example plants have cellulose lining their cells (which is not easily digestible), unless you physically break those bonds, the nutrients and energy containing molecules inside are inaccessible (cows have four stomachs for this reason). Cooking however, breaks down cellulose very nicely. Cooking will also break down protein in meat (and vegetables) making them more accessible to digestive enzymes. It's like how you digest well chewed food better than poorly chewed food, cooking breaks down food. It's hypothesized the development of fire allowed for the evolution of the human brain (it takes up 1/4th of your calories, you know!

As for the stuff you derive energy from. There are starches, proteins, and fats. These are molecules that consist of long chains of smaller molecules (carbohydrate sugars, amino acids, and fatty acids respectfully) that can be used to make energy in the form of ATP molecules. Cooking can break down these chains, but the molecules tend to be ok. When they don't you get charcoal.