On the Internet, you have many options to help you determine your daily caloric needs, but with the following method, you can calculate your own, customized daily calorie needs, using a few straightforward equations and a calculator. This process will allow you to evaluate the activities that contribute to your daily calorie burn and see immediately how even small changes in your routine can impact your net calorie balance.
Step 1
Have your body fat percentage measured. You can do this in several ways: you can have it measured by a trainer at a gym, or by a nutritionist, or even have an underwater weighing, or you can get an estimate by using an online body fat calculator (see Resources). This final option will usually require you to enter some statistics about yourself, such as height, weight, and age or some simple measurements, such as waist, hip and neck.
Step 2
Compute the portion of your weight that is lean body mass (LBM). Multiply your body weight by 1, minus your percent body fat, that is, LBM = body weight x (1 - percent body fat). For example, if you weigh 158 lbs., and your percent body fat is 28 percent, then your LBM = 158 x (1 - 0.28) = 114 lbs.
Step 3
Figure the resting metabolic rate (RMR) for your LBM. RMR is the number of calories your body uses in a 24-hour period of doing nothing but sitting still. Your RMR can be measured in a laboratory setting with a procedure known as indirect calorimetry, you can estimate it fairly accurately with one of several regression equations. One such equation, published in the "American Journal of Clinical Nutrition," by researcher J.J. Cunningham, reads as follows: RMR = 370 + 9.81 x LBM in pounds. Continuing with our above example of 114 lbs. of LBM, that yields RMR = 370 + 9.81 x 114 = 1,488 calories.
Step 4
Divide your daily RMR by 24 to give an hourly RMR. Again, with our example, that would be hourly RMR = 1,488 / 24 = 62 calories per hour.
Step 5
Determine the metabolic equivalent task values (MET) for all your daily activities. You can find these values in a document known as the "Compendium of Physical Activities for Year 2000," which is stored on-line at the University of South Carolina School of Public Health website (see Resources). Look up everything you do, including eating, sleeping, and bathing. Here are some examples: running at 5 mph, MET = 5; knitting, MET = 1.5; speed skating, MET = 15. Interpret these numbers as "speed skating uses 15 times as many calories per hour as sitting still."
Step 6
Compute the total number of calories you burn while engaging in these activities. This will be the product of your hourly RMR, the MET value of the activity and the hours you engage in the activity. For example, if you sat in front of your fireplace, knitting, for two hours, the calories you burned in those two hours--total, not in addition to your RMR--would be computed like this: 62 calories/hour x 2 hours x 1.5 MET = 186 calories.
Step 7
Calculate your total calories needed for the day by adding up all the activity calories. Here is a full-day example: sleeping, 62 x 8 hours x 0.9 MET = 446; showering and grooming, 62 x 2 hours x 2 MET = 248; working at a desk, 62 x 7 hours x 1.8 MET = 781; doing household chores, 62 x 2 hours x 2.5 MET = 310; running at 10 MPH, 62 x 1.5 hours x 4 MET = 310; reading, talking, and eating, 62 x 2.5 hours x 1.5 MET = 326; watching TV in bed, 62 x 1 hour x 1.0 MET = 62. The total for the 24 hours adds up to 2,483 calories. So, your weight-stable calorie needs would be 2,483 per day.
Tips and Warnings
- You can bypass the first three steps, which you determines your RMR, by using an online RMR calculator (see Resources). These may use a different equation, but the results should be similar. Once you have the RMR, you can pick up the process with Step 4.
- These figures are based on regression equations, which means they were developed by examining the results of a large, diverse group of people, and are therefore, widely applicable. However, your particular circumstances may make you an "outlier," meaning the equations may not be accurate for you. Such circumstances might be, for example, if you are an elite athlete, or have a metabolic disease. If your lean body mass changes significantly over time, you will need to recalculate to get an updated hourly RMR.
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