Your resting metabolic rate, or RMR, equals the number of calories your body requires to function at rest. Although genetic variances make it impossible to accurately determine your RMR without medical tests, you can use a formula to make a rough estimate. Once you know your RMR, you can determine how many calories you need in a given day by factoring in exercise and daily activities. When you add your RMR together with your activity factors, or AF, you will find your total energy expenditure, or TEE, which is the number of calories you need to sustain yourself and maintain weight.
Find Your RMR
Weigh yourself on the scale, preferably first thing in the morning before you have eaten.
Convert your weight to kilograms by dividing the number of pounds by 2.2.
For males:
If you are between 18 and 30 years old, multiply your weight times 15.3 and add 679 to that number.
if you're between 30 and 60, multiply your weight times 11.6 and add 879.
If you're over 60, multiply your weight times 13.5 and add 487.
The final number is your RMR.
For females:
If you are between 18 and 30 years old, multiply your weight times 14.7 and then add 496 to that number.
If you're between 30 and 60, multiply your weight times 8.7 and add 829.
If you're over 60, multiply your weight times 10.5 and add 579.
The final result is your RMR.
Find Your Total Energy Expenditure
Determine your activity factor, or AF, number:
Rest only: If you do not perform any activities throughout the day, but only lie down, your AF is 1.
Sedentary: If you only perform seated activities, such as reading books, your AF is 1.3.
Lightly active: If you perform light activities such as office work and chores, your AF is 1.6 if you are male, or 1.5 if you are female.
Moderately active: If you perform light labor, brisk walking or some sports throughout the day, your AF is 1.7 if you are male, or 1.6 if you are female.
Highly active: If you engage in athletics full time, your AF is 2.1 if you are male, or 1.9 if you are female.
Exceptionally active: If you perform heavy tasks such as construction all day long, your AF is 2.4 if you are male, or 2.2 if you are female.
Multiply your AF times your RMR. This number is the total number of calories you need per day to maintain weight.
If your goal is weight gain, Add 500 to 1,000 calories a day to put on 1 to 2 pounds a week. Conversely, remove 500 to 1,000 calories a day to lose 1 to 2 pounds a week. (ref 4)
Warnings
Consult a physician before beginning a new weight loss plan.