Those new age raw food diet hippies might be on to something. A new study has found that cooking food actually adds calories to it, making the information you see on nutrition labels flawed.
Richard Wrangham, the chair of biological anthropology at Harvard, started questioning the effects cooking had on calorie counts while studying chimpanzees in Tanzania. He noticed that, despite being such close relatives, humans wouldn't be able to live on the same diet as a chimp; something he attributed to the advent of cooking. He speculated that cooking not only changed the nutritional value and texture of food, but also added more energy.
He also noted that women who live on a completely raw food diet stopped having regular periods despite consuming the same amount of nutrients as someone on a cooked food diet. He concluded that eating raw food somehow didn't provide the necessary amount of calories to keep her fertile.
To prove his theory, Wrangham compared how adding heat versus processing the food in other ways (pounding, chopping) affected the diet of mice. Mice were fed the exact same amounts of sweet potatoes and meat. In one set, the food was cooked without any added oils or salts, in the other, it was raw and pounded. They found that the mice that ate cooked food gained more weight than the mice that ate raw food. He also found that mice were more excited to eat the cooked food than the raw food.
His findings could throw a wrench into the standardized calorie counts that have been accepted for certain foods. These counts don't factor in things like cooking and processing, and how these things affect digestibility.