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The Importance of Body Fat Testing

How to Assess the True Success of Your Weight Loss Program

By JJ Virgin, CNS, CHFI

Traditionally, we have measured our success on a "diet" or weight loss program by checking our scale weight. The challenge is that this number doesn't give us the whole picture. The most important thing you can do to ensure your long-term weight management success is to lose body fat (BF) while maintaining or increasing lean body mass (LBM). The scale doesn't distinguish between LBM and fat mass (FM), so you may get an inaccurate picture of your progress if you rely on this method alone.

I recommend body fat testing as an essential part of your weight-loss program. This method will show if you're successful in changing your metabolism into a fat-burning furnace and boosting your basal metabolic rate (BMR) by adding precious energy-demanding muscle. Muscle is a metabolic girdle — not only does it help to hold everything in tighter, it is also where you burn fat and it requires more energy to exist on your body. Each new pound is worth as much as 40 to 50 more calories a day.

There are many different ways to test BF, and most of them are just predictions of your actual body fat. This is satisfactory because you are looking for the relative change so that you can ensure that you are losing BF while preserving or increasing LBM. My favorite way to test body fat percentage is by bio-impedance using the Tanita BIA scale. This easy-to-use scale provides weight, body mass index, predicted BMR, body fat percentage and actual pounds of muscle and fat.

Bio Impedance (BIA) scales, like the Tanita scale we have been using with the Challengers, are based on total body water. This testing can be affected by hydration, women's monthly cycles and even time of day. They are the quickest, most economical and most consistent way to measure, providing that you control the variables (food, water, caffeine, alcohol and salt intake, time of day and exercise) as much as possible.

We have also done skinfolds using Lange Calipers. This technique is based on the premise that 50 to 70 percent of your fat lies directly below the skin. We know that as body fat percent rises (as you become weight-loss resistant or as you age), this hypothesis no longer holds true. By taking the measurements at multiple sites, we are able to use skinfolds to provide a picture of how you are losing weight. Skinfold percent and BIA should be within 2 to 3 percent of each another if you are healthy and not overstoring internal fat.

The range for ideal body fat is wide and varies, depending on which textbook you are referencing. Women have 10 to 15 percent essential fat (fat you must have to survive), and men have 3 to 5 percent essential fat. The BF ranges will vary, depending on whether you are athletic or not, and the ranges tend to increase with age, due to the loss of LBM. On a healthy weight management program, you can expect to lose 2 to 4 percent body fat a month. What I have used over the years is this:

Men:
  • Range 8-18 percent
  • Very athletic men: 5-12 percent
  • To be optimally healthy, you should strive to be 10-15 percent
  • You are overfat at greater than 18 percent, and clinically obese by body fat standards at 22 percent and above

    Women:

  • Range 17-27 percent
  • Athletic women: 15-20 percent
  • Healthy 18-25 percent and optimal health 18-22 percent
  • You are overfat at greater than 28 percent, and clinically obese at 32 percent and above

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