sot/getty images

For women:

655 + (4.36 × your weight in pounds) + (4.32 × your height in inches) −
(4.7 × your age) =BMR

I did the math for a thirty-year-old woman who is 5 foot 6 inches tall and weighs
140 pounds.

BMR (equals) 655+ 609+ 310.2 − 141. Her BMR is 1433.2.

p. dazeley/getty images

For men:

66+ (6.22 × your weight in pounds) + (12.7 × your height in inches) −
(6.8× your age) =BMR

I did the calculations for a thirty-year-old man who is 6 feet tall and weighs 175
pounds.

BMR (equals) 66+ 1090.25+ 914.4 − 204. His BMR is 1866.65.

Once you know your BMR, factor in your activity level to figure out the exact
calories you need daily to maintain your weight.

1. If you are sedentary (little or no exercise), you multiply your BMR by 1.2.
   
   
2. If you are lightly active (light exercise/sports 1 to 3 days/week), you multiply
   your BMR by 1.375.
   
   
3. If you are moderately active (moderate exercise/sports 3 to 5 days/week),
   you multiply your BMR by 1.55.
   
   
4. If you are very active (hard exercise/sports 6 to 7 days a week), you multiply
   your BMR by 1.725.
   
   
5. If you are extra active (very hard exercise/sports plus a physical job or training
   twice a day), you multiply your BMR by 1.9.
   

Excerpted from:
Diet Myths That Keep Us Fat by Nancy Snyderman, M.D.
© 2009, Crown.

Get more weight-loss facts.