Energy intake (fat, carbohydrate, protein, and alcohol)=
Energy expenditure (resting metabolic rate, digestion and absorption, physical activity, exercise, and body homeostasis)
The energy intake part of the equation is pretty straight forward. It is all of the food that you put into your body. This, of course, is where dieting comes in to play. Simply cut back on the Calorie intake and you create a Calorie Deficit. This, alone, works in the short-term, but ultimately doesn't in the long-term. Decreased energy intake, ideally through portion control and proper eating habits, are still important to keep the energy intake side of the equation in check.
On the other side of equation, energy expenditure happens in a variety of ways. Most people know that increasing physical activity will result in an increase energy expenditure. However, most people don't understand how the resting metabolic rate plays an even larger role in energy expenditure. In just about everyone, unless you are Michael Phelps and train six hours a day, the resting metabolic rate is the largest component your energy expenditure. It is defined as the total amount of Calories used in 24 hours to maintain all cells in your body independent of eating or physical activity. This includes all basic cell activities like electrolyte transport, protein assembly, cell division, etc. This is on going and particularly expensive in active tissue, like skeletal muscles. In fact, there is a strong, direct relationship between total body muscle mass and resting metabolic rate. That means usually, the bigger the person, the higher the resting metabolic rate. Same is true for men versus women.
Exercise training, more specifically strength training, can elevate your resting metabolic rate, which in turn will elevate your daily energy expenditure. I will discuss this more in the next blog posting on this subject.