BMR stands for Basal Metabolic Rate. It is representative of the caloric requirement to sustain life at rest each and every day. You heard it right: BEING ALIVE BURNS CALORIES!
BMR is determined by a couple of factors: gender, age, genetics, weight, muscle mass, exercise, and much more. Knowing your own BMR value will help you lose/maintain weight efficiently.
Note: This formula is a rough estimate of your BMR value. BMR is affected by many factors and can be less or more than the value you find through this formula.
Here are the formulas. Note that height, weight, and age are in specific units. Next I will show you how to change your values to those units.
Here are ways to convert mass and height. Very simple equations. "2.2" and "2.54" are known constants.
Now that we know how to do these equations we can figure out our BMR! I will provide an example of a 22 year old man who is 5"10 and 210 lbs.
Here is the full equation worked out. His final tally is 2095.551 kcal/day at rest.
So what does this mean? This means that if that man were to do nothing all day long and lay in bed motionless, he would burn 2095.541 kcal. Any thing beyond laying in bed would burn more calories!
Once again...this is a rough estimate. To find your actual BMR, you would have to lay in a room with a calorimeter for 24 hours and do absolutely nothing. No one has time for that!
So there you have it. You burn calories by simply being alive. So from now on when you are lazy and in bed all day, just know that technically speaking, you are working hard!