Know Your Basal Metabolic Rate (BMR)
Updated on July 28, 2007
BMR Calculator
BMR Calculation
| Date: | 5/17/2008 |
| Sex: | |
| Age: | |
| Height: | 0 in / 0 cm 0 ft / 0 m |
| Weight: | 0 lbs 0 kg |
| Est. Basic Metabolic Rate (BMR): |
0 calories per day (at total rest) Actual BMR varies from person to person. May be higher if you are pregnant, a child, a teenager, or have lots of muscle mass. May be lower if your metabolism is slow due to hypothyroidism, yo-yo dieting, or other disorders. |
What is BMR?
Your basal metabolic rate (BMR), also known as basal energy expenditure (BEE), is the number of calories you burn per day just by being alive and laying around. BMR is based on weight, height, and age, but there are more factors to consider.
Be forewarned, the rate you calculate may not be accurate. If you are muscular, your BMR will actually be higher than the calculated rate because muscles are always using energy and burn calories even when they aren't doing anything. If you are fat, your BMR will actually be lower than the calculated rate because fat cells store energy rather than use energy. Either way, at least you can get an idea of your maximum or minimum BMR depending on your situation. Women generally have more fat, and men generally have more muscle, so there are two separate equations for the calculation.
Calculating Men's BMR (using the Harris-Benedict formula)
BMR = 66.4730 + (6.23 x weight lbs.) + (12.7 x height in.) - (6.775 x age)
or
BMR = 66.4730 (13.7516 x weight kg) + (5.0033 x height cm) - (6.7550 x age)
Calculating Women's BMR (using the Harris-Benedict formula)
BMR = 655.0955 + (4.35 x weight lbs.) + (4.7 x height in.) - (4.6756 x age)
or
BMR = 655.0955 + (9.5634 x weight kg) + (1.8496 x height cm) - (4.6756 x age)
Using Your BMR to Help You Lose Weight
When trying to lose weight, your goal is to burn more calories than you eat. This will force your body to use its fat reserve to make up for the calories you aren't eating. This is a balancing act.
You're first reaction may be, "Great, I'll just eat less to lose weight." It's not that easy, though. If you starve yourself by dieting, your BMR will actually slow down because your body thinks it's starving and will try to conserve energy. When your body tries to conserve energy, it makes it harder and harder to lose weight. When you do start eating again, it will quickly try to store all those calories rather than use them right away, and you could end up fatter than you were before you started dieting. True, you could become anorexic and lose weight by dieting alone, but you won't be very healthy, and you'll probably look like a skeleton and feel miserable, so don't waste your time using such methods.
This doesn't mean that you can ignore your diet completely, though. You need to eat a reasonable number of calories. If you're trying to lose weight, your maximum number of calories per day will probably be somewhere around 2000. Do a food journal, and record how much you eat and how many calories are in that amount (read those labels) every day for a week. If you're eating significantly more than 2000 calories per day, you need to do some extreme diet changes.
If you exercise, you actually burn more calories than your BMR calculation suggests. The more exercise you do, the more calories and fat you burn. How much more? This is where those calorie burning calculators come in handy. They aren't necessarily accurate either, but they can give you a general idea of how your activity influences your BMR.
Exercise also increases your BMR (unlike dieting), so you'll burn more calories while you're just sitting than you would if you were dieting alone.
Example
Let's say you are a 30-year-old woman who is 5'2" and weigh 200 lbs. (This would be me when I started my weight loss journey.)
Your BMR would be 1673 calories/day. That's about 70 calories per hour.
Let's say you also have a sedentary job where you sit behind a computer 8 hours a day. That sitting burns about 600 to 700 calories per day.
That's 2273 calories per day burned by just working and living.
If you walked at a moderate pace (not a stroll, not speed walking) for 30 minutes every day, you would burn an additional 150 to 200 calories per day.
Now you're daily calorie burning is up to 2423.
If you want to burn fat, you'll need to eat less than 2423 calories per day. If you wanted to lose one pound per week (3500 calories = 1 lb.), you would need to eat no more than about 1900 calories per day. If you want to eat more and still lose one pound per week, you'll have to add more exercise. If you want to lose two pounds per week, you'll need to eat 1400 calories per day or add enough exercise to burn 500 calories more per day. (Always try to add exercise rather than reduce the number of calories you eat because it is more effective in helping you lose weight.)
Sources: Harris J, Benedict F. A Biometric Study of Basal Metabolism in Man
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