Fat is the crucial factor when considering weight. Excess fat can lead to a host of medical problems, including diabetes and heart disease. Body fat percentage is what people use to identify the amount of weight attributed to fat versus lean body mass. You can use your current weight and body fat percentage to determine the amount of weight you need lose to lower your body fat.
Step 1
Step on the scale to get your weight and body fat percentage. Record these numbers on your paper.
Step 2
Multiply your weight by your body fat percentage to determine the portion of your weight that is fat. For example, if you weigh 150 lbs. and your body fat percentage is 30, multiply 150 X 0.30 to get 45 lbs. Some scales provide this number for you.
Step 3
Subtract your fat weight from your total weight to obtain your lean mass weight. For example, if you weigh 150 lbs. and your fat weight is 45, subtract 45 from 150 to get 105 lbs.
Step 4
Determine your body fat percentage goal. Sports Fitness Adviser recommends that women up to the age of 30 should have body fat of 14 to 21 percent. From age 30 to 50, body fat should be 15 to 23 percent and over 50 years 16 to 25 percent. Men under 30 should have body fat of 9 to 15 percent, increasing to 11 to 17 percent from 30 to 50 years of age and 12 to 19 percent over 50 years.
Step 5
Subtract your goal body weight percentage from 100. If your goal is 20 percent body fat, subtract 20 from 100 to get 80. Your goal lean mass is 80 percent.
Step 6
Divide your lean body mass from step 3 by the goal lean mass in step 5. If your lean mass is 105 and your goal lean mass is 80 percent, divide 105 by 0.80 to get 131.25 lbs. This is your goal weight.
Step 7
Subtract your goal weight from your current weight to determine how much weight you need to lose to reach your body fat percentage goal. If you weight 150 lbs. and your goal weight is 131.25, your weight loss goal is 18.75 lbs.
Tips and Warnings
- If your scale doesn't measure body fat, visit a gym that can use a handheld body fat scale or calipers to take your measurements.
- Retake your body fat percentage several times during the course of your weight loss. It is possible to lose or gain lean body mass, which changes your calculations.
Things You'll Need
- Scale with body fat percentage
- Paper and pencil
- Calculator
References
- "Personal Trainer Manual"; American Council on Exercise; 2008
- BodyBuilder.com: Questions and Answers; Todd Opheim
- Sports Fitness Advisor: Body Fat Percentage: What Gets Measured Gets Managed
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