Negative Calorie Foods, Fact or Fiction?
The Negative Calorie Diet Theory
The phrase, “negative calorie food”, as highlighted in negative calorie diet programs and books, usually refers to foods that allegedly require more energy to digest than they contain. Since the process of digestion requires the use of calories for energy, sometimes the net amount of metabolizable energy available from a food is less than the gross number of calories contained in the food.
However, there is actually no such thing as a negative calorie food, if your definition of negative calorie food is that more calories are required to digest, aborb and assimilate the food than are contained in the food. In reality, the energy required to digest the food is only a small percentage of the total calories.
The Thermic Effect of Food, Explained
The energy used to digest food is known as the thermic effect of feeding. The thermic effect of each food varies based on the food type:
Dietary fat has the lowest thermic effect of only about 3-5%
Carbs have a thermic effect of about 15%
Proteins have a thermic effect of about 30%.
You may notice that fruits and vegetables make up most negative calorie food lists, but protein foods have the highest thermic effect. A significant amount of calories are required to digest and process proteins. In a protein food like a chicken breast, if a serving contained 200 calories, 30% or 60 calories may be required for the process of digestion. Therefore, the available metabolizable calories remaining are approximately 140.
Lean Protein Foods Have the Highest Thermic Effect
Not only do lean proteins have the highest thermic effect…