Your TDEE, or Total Daily Energy Expenditure, is the total number of calories you burn every day. Calculate your TDEE by applying an activity modifier to your BMR or basal metabolic rate. Determine your BMR using the Katch-McArdle Formula if you know your body fat percentage, or the Harris-Benedict Formula if you do not know your body fat percentage.
BMR Based on Lean Body Mass
Step 1
Calculate your lean body mass by subtracting the weight of your body fat from your total weight. Lean body mass = weight - (weight x body fat percentage). If you weigh 150 lbs. and have 25 percent body fat, your lean body mass = 150 - (150 x 0.25) = 150 - 37 = 113.
Step 2
Use the formula BMR = 370 + (21.6 x lean body mass in kilograms) or BMR = 370 + (9.8 x lean body mass in pounds).
Step 3
Calculate BMR for a lean body mass of 100 lbs. for example, as follows: BMR = 370 + (9.8 x 100) = 1,350 calories. So, if you have a lean body mass of 100 lbs. and you lie in bed for 24 hours, you would need to 1,350 calories during that period to maintain your weight.
Harris-Benedict Formula
Step 1
Use the sex-specific Harris-Benedict Formula to calculate BMR if you do not know your body fat percentage.
Step 2
Use the following formulas to calculate your BMR if you are a woman: BMR = 655 + (9.6 x weight in kg) + (1.8 x height in cm) - (4.7 x age in years) or BMR = 655 + (4.354 x weight in pounds) + (4.569 x height in inches) - (4.7 x age in years).
Step 3
Calculate your BMR if you are a man as follows: BMR = 66 + (13.7 x weight in kilograms) + (5 x height in cm) - (6.8 x age in years) or BMR = 66 + (6.213 x weight in pounds) + (12.69 x height in inches) - (6.8 x age in years).
Apply Activity Modifier
Step 1
Find the TDEE by multiplying your BMR by the appropriate activity modifier.
Step 2
Multiply by 1.2. for light activity, meaning a desk job and light exercise three or fewer days a week. If you are moderately active, use a multiplier of 1.55. If you are active and engage in intense exercise at least six days a week, multiply by 1.725. If you have an intensely physical job or do several hours of exercise a day, multiply by 1.9.
Step 3
Use the TDEE, the end product of the BMR with the activity modifier, as your calorie needs for each day.
Tips and Warnings
- Use online BMR and TDEE calculators to simplify the process.
- Genetic predisposition, illnesses, specific conditions and environmental factors can affect BMR and TDEE. Your health care provider can give you a more precisely tailored individual calculation.
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