Rather than relying on standard, generic calorie charts or tables, you can accurately estimate the number of calories that you burn in a day by using your own individual resting metabolic rate and the activities that you perform every day. By using this approach, you will have a much more personalized estimate of your daily calorie burn than those tables can offer.
Step 1
Figure your body weight in kilograms. If you already know this, skip this step. If you don't, take your body weight in pounds and divide it by 2.2. For example, if you are 175 pounds, your weight in kilograms is 175 / 2.2 = 80 kilograms.
Step 2
Calculate your fat-free mass (FFM) in kilograms. Take your weight in kilograms and multiply it by (1 - your body fat percentage). Continuing the example above, with 80 kilograms of body weight and a body fat percentage of 12, your FFM will be 80 x (1 - 0.12) = 70 kilograms.
Step 3
Determine your resting metabolic rate (RMR), which is your calorie burn for 24 hours of sitting still. There are several different equations for calculating RMR, but one of the simplest is the Cunningham RMR equation, which is RMR = 370 + 21.6 x FFM. Again, with the above example, you would get RMR = 370 + 21.6 x 70 = 1,882 calories.
Step 4
Translate the daily RMR to an hourly rate. Simply divide the RMR by 24, for example, with the RMR from the last step, hourly RMR = 1,882 / 24 = 78 calories per hour.
Step 5
Learn the metabolic equivalent task values (MET) for all activities and exercises you do in a day. You can find these values in the "The Compendium of Physical Activities" at the website of the University of South Carolina School of Public Health (see Resources). To give you an idea, here are some sample MET values: running at 10 miles per hour, MET = 10; speed skating, MET = 15; yoga, MET = 2.5.
Step 6
Calculate the calories you burned performing these activities. Take the product of your hourly RMR, the number of hours you spent in each activity, and the MET value for the activity. For example, with our 70 kilogram FFM person from above, thirty minutes of yoga would be calculated as follows: hourly RMR x time spent x MET = 78 x .5 x 2.5 = 98 calories. Note that 98 calories is the total calories burned for that half hour, not in addition to the RMR calories.
Step 7
Add up all the activity calories for the entire 24 hours of the day, even when the "activity" is doing nothing. Here is an example day for our 70 kilogram FFM person: sleeping, 78 x 8 hours x 0.9 MET = 562; showering and grooming, 78 x 2 hours x 2.0 MET = 312; working at a desk, 78 x 7.5 x 1.8 MET = 1,053; doing household chores, 78 x 2 hours x 2.5 MET = 390; yoga, 78 x .5 hours x 2.5 MET = 98; reading, talking, and eating, 78 x 3 hours x 1.5 MET = 351; watching TV in bed, 78 x 1 hour x 1.0 MET = 78. The hours add up to 24, as they should, and the calories burned for the whole day add up to 2,844.
Tips and Warnings
- If you don't know your body fat percentage, you can get it from a personal trainer or nutritionist, or estimate it with an online calculator (see Resources). In lieu of using the Cunningham equation to calculate RMR, you can find online calculators that will do it for you (see Resources).
- The equations and tables referred to are all based on statistical averages and confidence intervals, so they may not apply to every person and every situation, for example, if you suffer from a metabolic illness such as thyroid disease or diabetes, or you are unusually fit, this process may not give you accurate results. As your weight or lean body mass changes with a fat loss or muscle development program, you will need to come back and recalculate the values accordingly. The human body adapts to changes in calorie intake and activity output, so your initial results may not hold up over the long term.
Things You'll Need
- Body weight in pounds or kilograms
- Body fat percentage
- Table of metabolic equivalent tasks
- Calculator
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