People of the same sex and weight may have vastly different caloric requirements due to differences in height, activity level and amount of body fat. To accurately calculate the number of calories you need daily to maintain your current weight or safely lose pounds, you'll need to do a few mathematical calculations. With a calculator, you can accurately determine your current basal metabolic rate (the calories your body needs just to exist), your total energy requirement (calories you need to fuel activities of exercise and work), as well as your total food energy requirements (the calories you need to eat on a daily basis).
Determine Your Body Fat Percentage and Weight
Step 1
Determine your basal energy requirement, which is the number of calories your body requires to fuel basic life-sustaining functions like breathing, pumping blood and blinking. A fitness trainer at your gym can accurately weigh you and measure your body fat using hand-held bioelectrical impedance monitors or skin calipers.
Step 2
Figure out your body fat at home. Weigh yourself on your bathroom scale. Use a tape measure to measure your hips (widest part), your calf, thigh (at the upper thigh) and your wrist. Write these numbers down.
Step 3
Use the Home Body Fat Test at Health Central (see Resources). You will need the results for Section 2.
Calculating Basal Energy Requirement (BER)
Step 1
Determine the pounds of lean tissue (non-fat weight) that you have, based on the percentage of body fat you carry as calculated in Section 1. Lean tissue is composed of muscle, organs, bones, water and other nonfat tissues. (If you used the online test, you already have these numbers, skip to Step 3.)
Step 2
Calculate your fat weight by multiplying your body weight by your body fat percentage; that figure is your fat weight, the pounds of fat you are carrying on your body. To calculate your lean body weight, subtract the pounds of fat weight from your total body weight; the resulting figure is your lean body weight (LBW).
Step 3
Using your calculator, enter your lean body weight (LBW) and multiply it by your age factor to get your basal energy requirement (BER). If you are between 15 and 20 years of age, multiply your LBW by a factor of 16; for those 20 to 40 years of age, your age factor is 15; adults 40 to 50 years of age should use an age factor of 14; and those 50 years of age or older use an age factor of 13. For example, a 33-year-old man with a LBW of 145 would multiply 145 by 15 for a total BER of 2,175.
Calculating Your Total Energy Requirement (TER)
Step 1
Enter your lean body weight (LBW) into your calculator.
Step 2
Carefully consider how much exercise you do per day. If you are sedentary, skip this step and move on to Step 3. If you participate in up to 30 minutes of exercise or activity per day, multiply your LBW by a factor of 2. If you regularly exercise 30 to 60 minutes per day, multiply your LBW by a factor of 3. If you are active and regularly participate in 60 to 90 minutes of exercise or activity per day, multiply your LBW by a factor of 4. Write down the figure, which is your Activity Factor, as you'll need it for the next calculation.
Step 3
Determine your total energy requirement (TER), which is the number of calories you should eat per day to maintain your current weight, by taking your BER and adding your Activity Factor. The sum of these two figures is your TER.
Tips and Warnings
- If your goal is to lose weight, you'll need to reduce your caloric intake below what your body requires daily by 500 to 750 calories. When you have reached your goal weight or body fat percentage, or if you just want to maintain your current weight, use TER as your daily caloric intake. Re-check the figures every 4 to 6 weeks if you are on a weight loss or weight gain program.
Things You'll Need
- Tape measure
- Scales
- Calculator
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