Your basal metabolic rate is an indicator of how many calories your body burns at rest, and accounts for 60-75% of your overall metabolism!
Your official BMR is measured under very rigid conditions in an atmosphere completely void of any stimulation.
The person being measured would be awake, but totally relaxed and at rest.
In fact, an official test conducted by medical personnel would require a twelve-hour fast.
The information you receive from online BMR calculators, including this one, is more accurately referred to as a Resting Metabolic Rate. It is an approximate number of calories that your body needs to maintain normal function in an inactive state.
Your BMR decreases as you age, however, you can increase your BMR by increasing your lean muscle mass.
The following activity levels are often used with BMR:
The most up-to-date research indicates that for "basic health", you should exercise for a minimum of 30 minutes a day, at a moderate level of intensity, 5 days a week. For more significant health and fitness benefits, you would want to double that time or work out at a greater intensity. This research further states that if you are exercising at an intensity that makes conversation difficult, you can cut the recommended time in half (15 minutes) for basic health. Research still supports that 10-minute chunks are effective if you can't carve out 30 minutes at one time.