BMR stands for Body Metabolic Rate. It's calculation is used to estimate the number of energy producing calories your body needs to function at rest. From there, you can calculate what you are current calories you are taking in and go from there.There are a ton of of BMR calculators,
methods, and formulas out there, but the most important thing to realize
is that this is an estimate...an approximation of your body's daily caloric requirement. Basic BMR calculation is a good start, but as you know, most people do not lay in bed all day long. So, an accurate formula must take into account, sex, activity level, age, and height to get a total necessary daily calorie intake. Now, if you're trying to lose weight, obviously, you cut calories from the total, maybe 500-1000. To gain weight, lean mass or muscle, then add 500-1000. Again, only these are only estimates! The key, is to calculate your BMR using the formula below, and then, as always, strive for quality food choices, learn to eyeball portion size, and consistent-varied-progressive exercise.
Of the formulas I have checked out, one by Mark D. Mifflin and colleagues published an article in a 1990 issue of The American Journal of Clinical Nutrition seems to be the most accurate and simplest formula for these calculations.
Weigh yourself in pounds on a reliable scale. Convert your weight to kilograms by multiplying your weight in pounds by 0.4536. For example, if you weigh 150 lb., multiply 150 by 0.4536 to get 68 kg.
Measure your height in inches. Convert your height to centimeters by multiplying your height in inches by 2.54. For example, if you are 66 inches tall, multiply 66 by 2.54 to get 168 cm.
Calculate your resting energy expenditure, the calories you burn per day while resting:
(10 x weight in kilograms) + (6.25 x height in centimeters) - (5 x age in years) - 161
(10 x weight in kilograms) + (6.25 x height in centimeters) - (5 x age in years) + 5
For example, using the weight and height from above, if you are a 40-year-old female, your resting energy expenditure equals (10 x 68) + (6.25 x 168) - (5 x 40) - 161, which comes to 1,769 calories per day.
Multiply your resting energy expenditure by a physical activity factor to calculate your total energy expenditure. If you exercise less than three times per week, use 1.12 for your physical activity factor if you are female and 1.11 if you are male, according to Heather Fink, Lisa Burgoon and Alan Mikesky, authors of "Practical Applications in Sports Nutrition." If you exercise three to five times per week, use 1.27 if you are female and 1.25 if you are male; and if you exercise more than five times per week, use 1.45 if you are female and 1.48 if you are male.
Using the same example, if you exercise three to five times per week, your total energy expenditure equals 1,769 x 1.27, or 2,247 calories per day, which is the number of calories you should eat to maintain your weight of 150 lb.
Subtract around 500 to 1,000 calories from your total energy expenditure if you want to lose about 1 to 2 lb. per week, according to William McArdle, Frank Katch and Victor Katch, authors of "Sports and Exercise Nutrition." Conversely, add 500 to 100 calories to your total energy expenditure if you want to gain 1 to 2 lb. per week. Therefore, following the same example, if you want to lose 1 to 2 lb. per week, eat between 1,247 and 1,747 calories per day.
Another formula by estimates BMR by the Harris Benedict principle.
Women: 655 + (4.3 x weight in pounds) + (4.7 x height in inches) – (4.7 x age in years)
Men: 66 + (6.3 x weight in pounds) + (12.9 x height in inches) – (6.8 x age in years)
Other Important Things to Remember About BMR
- It doesn't take into account lean mass. If you have more muscle, your body needs more calories, even at rest. SO, to maintain your muscle, you have to eat more than the above BMR calculation factors. Have your body fat percentage read by a fitness or other health professional.
- If you are losing weight rapidly, then re-do BMR every 6-8 weeks
- Eat dense foods: quality fats and proteins as opposed to carbohydrates to keep insulin production at bay and yourself satiated.