When we have a meal, our body temperature tends to rise. This is because we need to expend energy to digest food, and to absorb and assimilate nutrients. Consequently, the calories available to you from food may not correspond exactly to the calorific content described on a food label. It is estimated that diet induced thermogenesis uses between 5 and 10 per cent of a meal's total energy, but the exact amount varies with the type of food. Our bodies seem to be relatively inefficient at utilizing carbohydrate, and less energy is available from it for storage and growth. Diet induced thermogenesis accounts for up to 23 out of every 100 calories when we eat complex carbohydrates, but only 3 out of every 100 calories when we eat pure fats. This is one reason fatty meals are so fattening!
Subjects: Medicine and Health.