How to Calculate Your Daily Calorie Needs
Katch-McArdle Formula

Calories/BMR - Katch-McArdle Formula

If you know your body fat and lean body mass (body muscle) percentage, you can obtain a fairly precise estimate of your BMR. For example, the formula from Katch & McArdle takes into account lean mass and therefore is more accurate than a formula based on total body weight.

The Katch-McArdle formula applies equally to men and women As Follows:

BMR = 370 + (21.6 X lean mass in kg)

BMR Example
You are female
You weigh 140 pounds (63.6 kilos)
Your body fat percentage is 25 percent (35 pounds fat, 105 lean)
Your lean mass is 105 pounds (47.7 kilos)
Your BMR = 370 + (21.6 X 47.7) = 1400 calories

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

BMR Example
Your BMR is 1400
Your activity level is moderately active
Your activity factor is 1.55
Your total = 1.55 X 1400 = 2170 calories
Your total daily calorie requirement is therefore 2170 calories.
This is the total number of calories you need in order to MAINTAIN your current weight.

Source:
Katch, Frank, Katch, Victor, McArdle, William. Exercise Physiology: Energy, Nutrition, and Human Performance, 4th edition. Williams & Wilkins, 1996.

How Many Calories Do You Need to Lose Weight or Gain Weight

Now you know what your calorie-needs are, find out how many calories you need each day in order to lose or gain weight.