For this to happen, the amount of calories burned must exceed the number of calories consumed, regardless of the content of nutritional components. Metabolism is the rate at which the body uses energy to support basic functions essential to sustaining life. This metabolism is made up of three parts, which include physical activity (20%), the thermic effect of food, also called TEF (10%), and the rate of resting metabolism or REM (70%). Physical activity is the amount of energy your body expends. it burns during normal daily activities, including housework, recreational activities, work, exercise, and so on. Obviously, a physically active person will burn more energy than a sedentary person. TEF represents the energy used to digest and absorb nutrients, which varies depending on the composition of the meal. When a person eats too much, TEF increases because more food must be digested. This is where metabolism gets very interesting and causes so much confusion. One pound equals 3,500 calories, so let's say a person consumes 3,500 more