We burn energy (calories) when we metabolize the food we eat. In other words, it takes energy to digest, absorb and process the nutrients we consume, and this is the “Thermic Effect of Food”.
The thermic effect of the different macronutrients are as follows:
The precise thermic effect varies,but it is obvious that it takes a lot less energy or calories to metabolize fats or carbohydrates than it does to metabolize protein. Let’s say the thermic effect of protein is 25% and the thermic effect of fat is 2%. This means that if you were to consume 100 calories of protein you would end up with 75 calories, while if you were to consume 100 calories of fat you would end up with 98 calories.
In addition to protein, whole foods have a higher thermic effect than processed foods. One study compared the thermic effect of a sandwich made with whole grain bread and cheddar cheese with a sandwich made from refined grains and processed cheese. The result – digesting the whole grain sandwich burned twice the calories of the sandwich made with refined grains.
In short, calories from protein and whole foods require more energy to digest than calories from processed foods. Keep this in mind if you are looking to lose weight.