Your BMR (basal metabolic rate) is the number of calories your body needs each day
to simply perform basic functions. From the time you go to sleep one night until
you go to sleep the next night, your body is using calories to fuel the body. Nearly
75 percent of the calories you eat each day are used by the body for this purpose.
You expend energy no matter what you're doing -- even when you are sleeping. It
takes calories each day to breathe, build new red and white blood cells, build muscle
tone, pump blood throughout the body, think, raise or lower your body temperature,
and all other basic body functions -- not to mention the calories needed for moving
around, working, reading and everything else you do in a day.
If you've noticed that every year, it becomes harder to eat whatever you want and
stay slim, you've learned that your BMR decreases as you age. Likewise, depriving
yourself of food in hopes of losing weight also decreases your BMR, as your body
adjusts how it burns fuel depending upon the amount of fuel it is given.
If you eat more calories than your body metabolism needs, you will gain weight.
There are 3,500 calories in every pound of body fat. So, if you eat 500 calories
more a day than your body needs, you will gain one pound every week.
Knowing your BMR can help you maintain your weight, because you will know approximately
how many calories you need each day to perform basic bodily functions; and help
you determine your exercise needs.
Your BMR is influenced by many factors:
Gender -- Men have a greater muscle mass
and a lower body fat percentage. This means they have a higher basal metabolic rate
Medications -- Some drugs slow down the
Genes -- Some people are born with faster
metabolisms, some with slower metabolisms; this genetic metabolic fact cannot be
Age -- BMR reduces with age. After age
20, it drops about 2 per cent per decade
Exercise -- Physical exercise influences
body weight by burning calories, but it also helps raise your BMR by building extra
lean tissue (lean tissue is more metabolically demanding than fat tissue), so you
burn more calories even when sleeping
Weight -- The more your weight, the higher
your BMR; for example: the metabolic rate of obese women is 25 percent higher than
the metabolic rate of thin women
Body Surface Area -- The greater your
body surface area factor, the higher your BMR, i.e., tall, thin people have higher
Body Fat Percentage -- The lower your
body fat percentage, the higher your BMR; the higher body fat percentage in the
male body is one reason why men generally have a 10-15 percent higher BMR than women
Diet -- Starvation, eating disorders
or serious abrupt calorie-reduction can dramatically reduce BMR by up to 30 percent;
restrictive low-calorie weight loss diets may cause your BMR to drop by as much
as 20 percent
Other Factors -- Other factors include:
body temperature and health, hormones, external temperature, and glands/ glandular
A regular routine of cardiovascular exercise can increase your BMR, improving your
health and fitness when your body's ability to burn energy gradually slows down.
Calculating Your BMR
Calculate calories for basic needs.
Multiply your weight in pounds by 10 (for women) and 11 (for men).
___ lbs. x 10 = _____ calories for basic needs
Calculate calories for physical activity.
Use the chart below to determine your activity level.
_____calories for basic needs x ___% activity level = ____calories
Examples of Activities
Sitting, driving, sleeping, reading, typing
Light exercise, < 2 hours per day
Moderate exercise, gardening, dancing, little sitting
Active in physical sports or labor-intensive job, such as construction
Calculate calories for digestion of food.
Add calories for basic needs (#1) and calories for activity level (#2), then multiply
(___calories for basic needs + ____calories for activity) x 10%
= ___calories for digestion
Calculate total energy needs.
Add calories from each section to get total energy needs.
___calories for basic needs + ___calories for activity +___calories
for digestion = ____total energy needs
To lose weight, you need to take in fewer calories than your total energy needs.
To gain weight, you need to take in more calories than your total energy needs.