Your BMR is the number of calories your body burns in a day when operating at absolute minimum capacity. Basically, imagine sitting on the couch all day. (Is this a little too easy for you to imagine? Don't worry — we'll fix that!) Your BMR, then, is the number of calories your body burns just to maintain your heartbeat, digestion, respiration, tissue repair and other organ functions. That's it.
BMR is influenced by a number of factors, including age, weight, height, gender, environmental temperature, and diet and exercise habits. Because of these varying factors, it's hard to pin down your BMR to the precise calorie, but we can get pretty close. Here are some formulas for figuring out your BMR. Get out your calculator and plug your numbers into whichever formula applies to you.
MALE: 66 + (6.3 × body weight in pounds) + (12.9 × height in inches) − (6.8 × age in years)
FEMALE: 655 + (4.3 × weight in pounds) + (4.7 × height in inches) − (4.7 × age in years)
Your basal metabolic rate accounts for only about 75 percent of your total daily caloric expenditure. You can also increase your BMR with exercise.