Cooked food is easier to digest and extract calories from, which scientists feel was probably an important factor in human evolution after our ancestors invented cooking. Below are listed foods and their digestibility both raw and cooked.
Food Raw Cooked
Potato 32% 98%
Egg 65% 99%
Wheat 71% 96%
Oats 75% 96%
Peas 80% 91%
Barley 93% 99%
What about meat. Digesting raw meat is difficult, using up about 1/3 of the energy you have just consumed.
The above figures help explain why people on a raw vegetarian diet often report persistent hunger and have a lower BMI than vegetarians who eat cooked food. I feel the Ayurvedic dietary recommendation that 2/3 of our foods should be cooked (preferably lightly steamed) and 1/3 eaten raw is the best advice for the majority of people