Choosing Your Ideal Size

Fat and Muscle Weight Are Quite Different

Another significant measure of body size is body fat percentage. The higher your body fat percentage, the more at risk you are for health issues related to being overweight or obese. When you have your body fat tested at a health club or at the doctor's, the machine gives you a reading of body fat, water, and muscle percentages. All three add up to 100 percent. Assuming that the amount of water weight remains almost constant for each individual, the variables are body fat and muscle. The more muscle you have, the less body fat you have (and vice versa). Muscle weighs three times more than fat.

Here are ideal body fat percentages:

Women: Up to age 20 14-21%
Age 20 to 50 17-27%
Age 50+ 20-30%
Men: Up to age 20 9-15%
Age 20 to 50 14-21%
Age 50+ 19-23%

In body fat measurements, lower is not necessarily better. A person must have at least some body fat to be healthy. Fat pads internal organs such as the kidneys, and it also offers protection against cold weather. For women, the minimum recommended fat percentage is 12 percent. If a woman has less, her menstrual cycles could cease. Men must have a minimum of 5 percent to stay healthy.

As you lose weight and do strength-building exercises, your body fat percentage goes down, and your muscle mass increases. This is good because having more muscle gives you the following:

  • More physical stamina
  • More energy
  • A higher metabolic rate
  • Better muscle definition
  • Better shape (for guys, muscle definition; for gals, curves)
  • Higher weight as measured on a scale
  • Lower risk of diseases associated with being overweight or obese

By doing strength-training exercises for as little as six months at two to three hours a week, you can reduce your body fat percentage by as much as 10 percentage points.

A high percentage of body fat is not good. More body fat puts you at a higher risk for diabetes and other medical conditions associated with being overweight or obese, such as high blood pressure, elevated triglyceride levels, metabolic syndrome, cancers, autoimmune disorders, and heart disease. In addition, you will have less energy, a slower metabolic rate, and a flabby body.

Using body fat percentage as a method to measure your ideal size can be misleading. It's part of the picture, but it's not the total picture. One client, Susie, had a body fat reading of only 19 percent. She wore a size 10. However, her waist was quite thick, and her muscles were so large that she didn't like how she looked in clothes. Her jeans didn't fit. Her body fat percentage was ideal, but she still was a larger size than she wanted. Susie needed to eat and exercise differently. Consider using body fat as one measure of your goal, but not the only measure.


Excerpted from The Complete Idiot's Guide to Healthy Weight Loss © 2005 by Lucy Beale and Sandy G. Couvillon. All rights reserved including the right of reproduction in whole or in part in any form. Used by arrangement with Alpha Books, a member of Penguin Group (USA) Inc.

To order this book visit the Idiot's Guide web site or call 1-800-253-6476.


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