Basal metabolic rate, or BMR, is the minimum number of calories needed to sustain basic body functions at rest. Resting metabolic rate, or RMR, is similar but includes calories burned during complete rest. There are several formulas to estimate BMR based on factors like weight, height, age, gender and body fat percentage. These include the Mifflin-St Jeor equation and revised Harris-Benedict equation. To determine daily calorie needs, BMR is multiplied by an activity factor depending on exercise frequency and intensity, ranging from 1.2 for sedentary to 1.9 for extra active lifestyles. However, accuracy may be improved by considering additional individual factors.

1. Basal metabolic rate
BY
Ramez Yousry

2. Basal metabolic rate vs. resting
metabolic rate
• Basal metabolic rate (BMR) is often used
interchangeably with resting metabolic rate
(RMR). While BMR is a minimum number of
calories required for basic functions at rest,
RMR — also called resting energy expenditure
(REE) — is the number of calories that your
body burns while it’s at rest.

3. BMR estimation formulas
• Mifflin-St Jeor Equation:
• For men:
• BMR = 10W + 6.25H - 5A + 5
• For women:
• BMR = 10W + 6.25H - 5A - 161

4. BMR estimation formulas
• Revised Harris-Benedict Equation:
• For men:
• BMR = 13.397W + 4.799H - 5.677A + 88.362
• For women:
• BMR = 9.247W + 3.098H - 4.330A + 447.593
• Katch-McArdle Formula:
• BMR = 370 + 21.6(1 - F)W
• where:
• W is body weight in kg
H is body height in cm
A is age
F is body fat in percentage

5. How many calories you need
everyday
• If you’ve estimated your BMR using the Harris-
Benedict formula, your next step is to include the
number of calories you burn during daily
activities based on your lifestyle:
• Sedentary. If you get minimal or no exercise,
multiply your BMR by 1.2.
• Lightly active. If you exercise lightly one to three
days a week, multiply your BMR by 1.375.
• Moderately active. If you exercise moderately
three to five days a week, multiply your BMR by
1.55.

6. How many calories you need
everyday
• Very active. If you engage in hard exercise six to seven
days a week, multiply your BMR by 1.725.
• Extra active. If you engage in very hard exercise six to
seven days a week or have a physical job, multiply your
BMR by 1.9.
• The final number is approximately how many calories
you need on a daily basis to maintain your weight.
• Of course, this is an estimate. According to a 2007
studyTrusted Source, the formula would be more
accurate if it included body composition, weight
history, and other factors that have been shown to
affect BMR.

7. Ref
• Ability of the Harris Benedict formula to
predict energy requirements differs with
weight history and ethnicity2007:
• Crystal C. Douglas,1,2 Jeannine C.
Lawrence,1,2,* Nikki C. Bush,1,2 Robert A.
Oster,2,3 Barbara A. Gower,1 and Betty E.
Darnell2,3