Every moment you're alive, whether you're riding an exercise bicycle or sleeping, your body burns calories. The amount of calories your body burns breathing, circulating your blood and maintaining other systems essential to life -- your basal metabolism -- depends on your sex, your weight and your body fat percentage, although it can be estimated and used as a yardstick to determine your daily caloric demands.
Calculating Basal Metabolism
Step 1
Weigh yourself using a scale. If your scale measures your weight in pounds, convert it to kilograms by dividing your weight in pounds by 2.2.
Step 2
Measure your height using a measuring tape. If your measuring tape doesn't provide metric measurements, convert your height in inches to centimeters by multiplying it by 2.54.
Step 3
Calculate your age to the nearest month. Divide the number of months since your last birthday by 12 to convert months to a decimal equivalent. For example, if you're 35 years and 3 months, record your age as 35.25.
Step 4
Apply your measurements to the Harris-Benedict equation to compute your basal metabolism rate, or BMR. The equation for men is:
BMR = 66.5 + (13.75 x weight in kilograms) + (5.003 x height in centimeters) -- (6.775 x age)
Women should use this equation:
BMR = 655.1 + (9.563 x weight in kilograms) + (1.850 x height in centimeters) -- (4.676 x age)
This measurement estimates the amount of calories your body burns if you remain unconscious in bed for a 24-hour period.
Calculate Your Energy Expenditure
Step 1
Estimate the amount of calories you burn in average daily activities. If you work at a desk or are relatively sedentary, multiply your BMR by 0.2 to 0.3. If you have a job or a lifestyle where you move around most of the day, but don't exert yourself, multiply your BMR by 0.5. If you have a physically demanding job, such as moving furniture or as a construction worker, multiply your BMR by 0.6 to 0.8. This number is your lifestyle factor.
Step 2
Estimate the number of calories you burn each day in exercise. Because this amount varies widely by your size, the activity you perform and the length you perform it, look up your exercise on a calorie-expenditure table. (See Resources.)
Step 3
Add your lifestyle factor and the amount of calories you burn in exercise to your BMR to estimate how many calories you burn each day.
Things You'll Need
- Scale
- Measuring tape
- Calculator
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