I recently read a study which determined that just tapping your foot while sitting will burn more calories than just sitting.  In fact, a completely sedentary person burns between 800 and 1,500 calories per day, creating the energy for the daily functions of all the cells in the body. This is called our basal metabolic rate, or BMR.  Researchers also found that exercise burns calories not just while you are doing the workout, but also in the hours following the exercise.  You use energy and burn calories to bring your body back to its normal resting state.  

So that’s the good news, you burn calories when you’re not exercising and you burn calories after your exercise session is over, but, you burn the most calories while you are actually exercising. 

Researchers found that the two most important contributors to burning calories during exercise are the contracting muscles and the increased work of the heart and lungs. The frequency and power of muscle contractions are by far the major factors in determining the number of calories burned during exercise.  Faster heart rate and breathing also burn calories, but not nearly as much as movement of legs, arms, abdominal and back muscles.  In fact, moving the biggest muscles in your body – your back, legs and abs – burn the most calories.

Over time, your metabolism changes as you convert your flabby muscles into firmer and leaner muscle mass.   The more lean muscle mass you have, the higher your basal metabolic rate, the higher your BMR the more calories you burn even when you’re NOT working out.

It takes resistance or strength training to get this calorie burning benefit from exercise.  However, cardio exercise will not only burn calories it will strengthen your heart muscle, the best way to avoid a heart attack.  A good exercise regimen includes both resistance training and cardio training.
You can determine how many calories you should take in on a daily basis with the following formula:

 Activity Level                           Calories per Pound 
Very light (sedentary)                14

Light (if you walk)                     15 – 17

Moderate (if you jog)                17 – 19

Heavy (if you’re a gym rat)       20 – 23
Use your “ideal” body weight, the weight you want to be, not the weight you are.

 Example:
120lb X 18 (Moderate) = 2160 calories per day are needed to maintain 120 pounds of body weight daily
But choose those 2000+ calories wisely – keep this in mind:

Carbohydrates = 4 calories per gram

Protein = 4 calories per gram

Fat = 9 calories per gram