A story from Wired magazine reports that the traditional method for counting the calorie content of food is inaccurate, because it ignores how much energy the human body takes to process different preparations of the same food. The findings were presented by a panel of researchers American Association for the Advancement of Science.
... the panel reviewed a new spate of studies showing that foods are processed differently as they move from our gullet to our guts and beyond. They agreed that net caloric counts for many foods are flawed because they don’t take into account the energy used to digest food; the bite that oral and gut bacteria take out of various foods; or the properties of different foods themselves that speed up or slow down their journey through the intestines, such as whether they are cooked or resistant to digestion.
A major distinction comes when comparing raw foods, which use up a lot of calories to digest, with cooked foods, which are processed by your body more easily, and therefore result in more net calories left in your system.
One key area where the system is inaccurate, Wrangham reported, is in estimating the calories for cooked food. Cooked items often are listed as having more calories than raw items, yet the process of cooking meat gelatinizes the collagen protein in meat, making it easier to chew and digest—so it takes fewer calories to eat. Heat also denatures the proteins in vegetables such as sweet potatoes, said Harvard University evolutionary biologist Rachel Carmody, a postdoc who studies the energetics of digestion and organizer of the session.
My takeaway from this story is that, given a choice between eating a raw carrot and one cooked, raw is better. Same with any fruits, such as apples, or vegetables, like bell peppers, which don't need to be cooked to taste good.
When it comes to weight loss and weight control, the preparation method of your food should be a secondary or tertiary concern. Much more important is to eliminate addictive foods, such as anything with sugar or other sweeteners added, to eliminate inflammatory foods, like dairy and wheat, to eliminate systemic toxins, like transfats, preservatives, excess salts and fake sugars, and to control your portions. If you only eat good foods, and you eat one small meal every 5-6 hours, beginning with breakfast and ending with dinner, and you mix in a modest, healthy snack 2-2.5 hours after breakfast and lunch, you will be satiated and, if you are fat, you will lose weight. And if you add in 60 minutes of exercise every 24 hours, you will get in good shape in 6 months or less.