Calculating Calorie Needs
Calculating Calorie Needs from the Harris-Benedict Formula
A fairly accurate way to calculate your daily calorie needs is to determine basal metabolic rate (BMR) using multiple factors, including height, weight, age and gender, then multiply the BMR by an activity factor to determine your total daily energy expenditure (calories). One calculation method is the Harris Benedict formula.
The Harris-Benedict Formula
The Harris Benedict equation is a calorie formula using the variables of height, weight, age, and gender to calculate basal metabolic rate (BMR). This is more accurate than calculating calorie needs based on total body weight alone. The only factor it omits is lean body mass and thus the ratio of muscle-to-fat a body has. Remember, leaner bodies need more calories than less leaner ones. Therefore, this equation will be very accurate in all but the very muscular (Harris-Benedict will under-estimate calorie needs) and the very fat (Harris-Benedict will over-estimate calorie needs).
Two Steps to Determine Daily Calorie Needs
-
First, determine your BMR.
- Second, apply the Activity Multiplier.
Harris Benedict Formula for Women – STEP 1
BMR = 655 + (9.6 X weight in kilos) + (1.8 X height in cm) – (4.7 x age in years).
Notes:
1 inch = 2.54 cm.
1 kilogram = 2.2 lbs.
Example of BMR:
You are 32 years old
You are 5 feet 4 inches tall (162.5 cm)
Your weight is 185 pounds (84 kilos)
Your BMR is 655 + (806) + (291) – (150) = 1602 calories
Harris Benedict Formula for Women – STEP 2
To determine your total daily calorie needs, now multiply your BMR by the appropriate activity factor, as follows:
- If you are Sedentary – little or no exercise
Calorie-Calculation = BMR x 1.2 - If you are Lightly Active (light exercise/sports 1-3 days/week)
Calorie-Calculation = BMR x 1.375 - If you are Moderately Active (moderate exercise/sports 3-5 days/week)
Calorie-Calculation = BMR x 1.55 - If you are Very Active = BMR x 1.725 (hard exercise/sports 6-7 days/week)
Calorie-Calculation = BMR x 1.725 - If you are Extra Active (very hard daily exercise/sports & physical job or 2X day training)
Calorie-Calculation = BMR x 1.9
Total Calorie Needs Example
If you are sedentary, multiply your BMR (1602) by 1.2 = 1922
Your total daily calorie requirement is therefore 1922 calories.
This is the total number of calories you need in order to MAINTAIN your current weight.
Harris Benedict Formula for Men
BMR = 66 + (13.7 x weight in kilos) + (5 x height in cm) – (6.8 x age in years)
Notes:
1 inch = 2.54 cm.
1 kilogram = 2.2 lbs.
Example of BMR:
You are 25 years old
You are 6 feet tall
Your weight is 220 pounds
Your BMR is 66 + (1370) + (914) – (170) = 2180 calories
Harris Benedict Formula for Men – STEP 2
To determine your total daily calorie needs, now multiply your BMR by the appropriate activity factor, as follows:
- If you are Sedentary – little or no exercise
Calorie-Calculation = BMR x1.2 - If you are Lightly Active (light exercise/sports 1-3 days/week)
Calorie-Calculation = BMR x 1.375 - If you are Moderately Active (moderate exercise/sports 3-5 days/week)
Calorie-Calculation = BMR x1.55 - If you are Very Active = BMR x 1.725 (hard exercise/sports 6-7 days/week)
Calorie-Calculation = BMR x 1.725 - If you are Extra Active (very hard daily exercise/sports & physical job or 2X day training)
Calorie-Calculation = BMR x 1.9
Total Calorie Needs Example
If you are lightly active, multiply your BMR (2180) by 1.375 = 2997
Your total daily calorie requirement is therefore 2997 calories.
This is the total number of calories you need in order to MAINTAIN your current weight.
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