Calories (because I only get 60 characters)

So, the calories-in-calories-out crowd is right, but so is the "clean-eating crowd." Basically the amount of calories that you absorb (or burn) depends on the health of your gut, the amount of processing the food has been through, how it's been cooked, and maybe even what nationality you are. Does this end the age-old argument?

http://www.scientificamerican.com/article.cfm?id=science-reveals-why-calorie-counts-are-all-wrong&WT.mc_id=SA_sharetool_Twitter

"Merely counting calories based on food labels is an overly simplistic approach to eating a healthy diet—one that does not necessarily improve our health, even if it helps us lose weight."

"People differ immensely as well in what scientists have come to regard as an extra organ of the human body—the community of bacteria living in the intestines. In humans, two phyla of bacteria, Bacteroidetes and Firmicutes, dominate the gut. Researchers have found that obese people have more Firmicutes in their intestines and have proposed that some people are obese, in part, because the extra bacteria make them more efficient at metabolizing food: so instead of being lost as waste, more nutrients make their way into the circulation and, if they go unused, get stored as fat. "

"People also vary in the particular enzymes they produce. By some measures, most adults do not produce the enzyme lactase, which is necessary to break down lactose sugars in milk. As a result, one man's high-calorie latte is another's low-calorie case of the runs."

Summary:

"Even if we entirely revamped calorie counts, however, they would never be precisely accurate because the amount of calories we extract from food depends on such a complex interaction between food and the human body and its many microbes. In the end, we all want to know how to make the smartest choices at the supermarket. Merely counting calories based on food labels is an overly simplistic approach to eating a healthy diet—one that does not necessarily improve our health, even if it helps us lose weight. Instead we should think more carefully about the energy we get from our food in the context of human biology. Processed foods are so easily digested in the stomach and intestines that they give us a lot of energy for very little work. In contrast, veggies, nuts and whole grains make us sweat for our calories, generally offer far more vitamins and nutrients than processed items, and keep our gut bacteria happy. So it would be logical for people who want to eat healthier and cut calories to favor whole and raw foods over highly processed foods."