Jamie - About.com User
Women: BMR = 655 + (4.35 x weight in pounds) + (4.7 x height in inches) - (4.7 x age in years)
Men: BMR = 66 + (6.23 x weight in pounds) + (12.7 x height in inches) - (6.8 x age in years)
Calculate your active metabolic rate by starting with your basal metabolic rate and adjusting it by estimating your current level of activity. If you are:
- Sedentary (little or no exercise) - your AMR = BMR x 1.2
- Lightly active (light exercise/work 1-3 days per week) - your AMR = BMR x 1.375
- Moderately active (moderate exercise/work 3-5 days per week) - your AMR = BMR x 1.55
- Very active (hard exercise/work 6-7 days a week) - your AMR = BMR x 1.725
- Extra active (very hard exercise/work 6-7 days a week) - your AMR = BMR x 1.9
Accuracy Problems With the Harris - Benedict FormulaUnfortunately, the Harris - Benedict formula isn't perfect. According to the Academy of Nutrition and Dietetics, research studies have indicated the formula is about 90 percent accurate around 60 percent of the time. That means it could be way off about 40 percent of the time, which is rather disheartening. Even worse, when the formula was wrong, it overestimated the calorie needs of the research subjects so they were burning fewer calories than they thought.
The formula's problems with accuracy may be due to physical or genetic factors, and there's a good chance that many people overestimate how physically active they are. So why use the formula if it's not completely accurate? Because it's a good place to start. You can calculate your daily caloric need and if you don't lose or gain weight, you can adjust your daily calorie goal, but please don't consume fewer than 1,200 calories per day without medical supervision.
Want to change your diet? The first step is to start with the statistics - measure your body composition and decide on your goals.
Academy of Nutrition and Dietetics Evidence Analysis Library. "In non-obese individuals, what is the prediction accuracy and maximum overestimation and underestimation errors compared to measured resting metabolic rate when using the Harris-Benedict formula?" Accessed August 7, 2012. http://www.adaevidencelibrary.com
Crystal C. Douglas, Jeannine C. Lawrence, Nikki C. Bush, Robert A. Oster, Barbara A. Gower, Betty E. Darnell. "Ability of the Harris Benedict formula to predict energy requirements differs with weight history and ethnicity." Nutr Res. 2007 April; 27(4): 194-199. doi: 10.1016/j.nutres.2007.01.016.