BMR

Just how many calories do our cells need to function well? The number is different for every person. You may notice on the nutritional labels of the foods you buy that the "percent daily values" are based on a 2,000 calorie diet -- 2,000 calories is a rough average of what a person needs to eat in a day, but your body might need more or less than 2,000 calories. Height, weight, gender, age and activity level all affect your caloric needs. There are three main factors involved in calculating how many calories your body needs per day:

• Basal metabolic rate
• Physical activity
• Thermic effect of food

Your basal metabolic rate (BMR) is the amount of energy your body needs to function at rest. This accounts for about 60 to 70 percent of calories burned in a day and includes the energy required to keep the heart beating, the lungs breathing, the kidneys functioning and the body temperature stabilized. In general, men have a higher BMR than women. One of the most accurate methods of estimating your basal metabolic rate is the Harris-Benedict formula:

• Adult male: 66 + (6.3 x body weight in lbs.) + (12.9 x height in inches) - (6.8 x age in years)

• Adult female: 655 + (4.3 x weight in lbs.) + (4.7 x height in inches) - (4.7 x age in years)

(Note: The first number in the equation for females is, in fact, 655. Strange but true.)