What is the "specific dynamic action of food"?

According to Dr. Pierre Dukan, the specific dynamic action of food is the amount of energy it takes to break a food down to its basic unit so that it can be absorbed by the bloodstream. This is represented as a percentage of calories spent to break down the food.

According to Dr. Dukan, carbohydrates such as sugars have the lowest specific dynamic action and can be broken down the easiest, requiring 7 percent of calories to be spent. Fats and oils are the next hardest requiring 12 percent of the calories to be spent. Proteins are the most difficult to break down, requiring 30 percent of the calories to be spent.