Your basal metabolic rate (BMR) is the minimum amount of calories (energy) you need everyday just for survival. If you never worked out, walked anywhere or ate any food, you would still need calories to breathe and pump blood through your body. The BMR is the lowest rate of energy needed in the body, besides sleeping. Everyone's BMR is different, based on individual body composition, weight and height, but an estimate of your BMR can be calculated using the Mifflin equation.
Step 1
Take your weight (wt) in pounds (lbs) and convert it to kilograms (kg), using this equation:
wt in lbs / 2.2 = wt in kg.
For example, a 170-lb. woman weighs 77.27kg.
170 / 2.2 = 77.27
Step 2
Convert your height (ht) in inches to centimeters (cm) by using the formula:
2.54 x ht in inches = ht in cm.
A 5-foot, 2-inch woman is 62 inches tall. Plugging that into the equation, you get 157.48cm.
2.54 x 62 = 157.48 cm
Step 3
The Mifflin equation has one difference when calculating for men and women:
(10 x wt) + (6.25 x ht) - (5 x age) - 161 = BMR (women)
(10 x wt) + (6.25 x ht) - (5 x age) + 5 = BMR (men)
To find the BMR of the woman, who is 29 years old, in the previous example, use the equation:
(10 x 77.27) + (6.25 x 157.48) - (5 x 29) - 161 = BMR
772.7 + 984.25 - 145 - 161 = 1,450.95 calories
A bare minimum of 1,451 calories is needed daily by this woman for survival.
Step 4
To calculate the BMR of a 32-year-old man who is 6-foot, 3-inch, 230-lb., first convert his height and weight to metric units.
230 / 2.2 = 104.56 kg
2.54 x 75 = 190.5 cm
Step 5
Plug in the height and weight into the Mifflin equation for men:
(10 x wt) + (6.25 x ht) - (5 x age) + 5 = BMR
(10 x 104.56) + (6.25 x 190.5) - (5 x 32) + 5 = BMR
1,045.6 + 1,190.63 - 160 + 5 = 2,081.23
He needs a bare minimum of 2,081 calories a day for basic bodily processes.
Tips and Warnings
- The Mifflin equation was published in "The American Journal of Clinical Nutrition" because the previously used equation overestimated the BMR of the overweight and the obese population. In a clinical setting, BMR is calculated after a 12-hour fast and with more precise tests and calculations.
Things You'll Need
- Paper
- Pen
- Calculator
References
- "The American Journal of Clinical Nutrition;" A New Predictive Equation for Resting Energy Expenditure in Healthy Individuals;" MD Mifflin; 1990
- "Nutrition for Health, Fitness and Sport, 5th Edition;" Melvin H. Williams; 1999
- "Dynamic Nutrition for Maximum Performance;" Daniel Gastelu; 1997
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