Body composition is a much more accurate representation of a person’s leanness than scale weight or Body Mass Index (BMI), because it does not rely on height and weight alone to measure leanness. It measures the ratio of body fat to lean tissue and bone in the body, not scale weight.
This is important, because a person may have a high-scale weight (even for their height), yet have also have a high muscle-to-fat ratio which makes them extremely lean. That same person might be labeled overweight using the standard BMI calculation, which does not take into account body composition, only mass (weight) relative to your height, weight, age and gender.
Excess body fat, or a body composition with a high fat-to-muscle ratio is unfavorable because it increases the risk of cardiovascular disease, Type II diabetes, Metabolic Syndrome and certain cancers. Excess body fat, especially at levels considered obese, can also put stress on the joints and interfere with mobility and the ability to perform everyday activities.
Types of Body Composition Assessments.
There are several types of body composition assessments used. Some more accurate and expensive than others. Here are a few of the assessment test available.
Hydrostatic Weighing: The individual is seated in a chair connected to a scale in a tank of water. The density of the body is calculated from the ratio of normal body weight to underwater weight. The body fat is calculated from the density. Hydrostatic weighing is accurate and considered the "gold standard" for assessing body composition.
Anthropometry: One of the easiest and least expensive ways to assess body compositon. Anthropometry consist of skinfold calipers and circumference measurements. Circumference measures can be easily used to assess body fat. A cloth or plastic tape measure is required and exact anatomical lanfmarks must be used. The tape measure should be held firmly about the body without causing an indentation to the skin. Skinfold calipers work on the theory that 50% of body fat lies beneath the skin. Measuring the skin thickness at specific sites and adding the results. The results are then compared to a chart to find the body fat percentages.
BMI: Body mass index consist of measuring a persons height in inches and weight in pounds, then utilizing the BMI chart to calculate the BMI number. This number corresponds to a scale to determine body fat. This system is fast and easy, but should be used in conjunction with other forms of body assessment.
When measurements are taken using either of the methods mentioned, the results can be near accurate. The results can assist you and your trainer in setting realistic weight loss goals. General body fat percentages are listed below. These general percentages are only a guide.
WOMEN%- MEN%
Essential fat 10-13%- 2-5%
Athletes 14-20%- 6-13%
Fitness 21-24%- 14-17%
Health 25-31%- 18-24%
Obese 32 and higher- 25 and higher
Body fat measurements and the measuring tape are recognized as superior methods for measuring "weight loss". When one declares that they want to "lose weight", what they often mean is that they want to lose fat. So, now that you've had your body fat percentage measured, what does the number really mean?
First, your body fat percentage is simply the percentage of fat your body contains. If you are 150 pounds and 10% fat, it means that your body consists of 15 pounds fat and 135 pounds lean body mass (bone, muscle, organ tissue, blood and everything else).
A certain amount of fat is essential to bodily functions. Fat regulates body temperature, cushions and insulates organs and tissues and is the main form of the body's energy storage. The following table describes body fat ranges and their associated categories:
*General Body Fat Percentage Categories
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*American Council on Exercise
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Classification
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Women (% fat)
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Men (% fat)
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Essential Fat
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10-12%
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2-4%
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Athletes
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14-20%
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6-13%
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Fitness
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21-24%
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14-17%
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Acceptable
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25-31%
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18-25%
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Obese
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32% plus
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25% plus
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Knowing your body fat percentage can also help you determine if your weight loss goals are realistic. Remember, weight loss doesn't always mean fat loss. For example:
Let's say you're a 130# woman with 23% body fat, and you goal is to "lose 20 pounds":
Initial body fat: 130# x 0.23 fat = 30 # body fat
Lean body mass: 130# total - 30# fat = 100# lean body mass (bones, organs and all else)
Goal: 130# - 20# = 110 pounds
As you can see, the goal of losing 20 pounds is not realistic or healthy. At 110 pounds, this woman still requires 100# of lean body mass (bones, organs, etc.), but would only be carrying 10#, or only 9% body fat. From the chart above, you can see that this is a dangerously low percentage.
A better goal might be for the woman to reduce her body fat from 23% to 18%. In this case:
130# x 0.18 = 23 # body fat
100# lean body mass + 23 # = 123# goal weight
So, for this individual to achieve a lean, but healthy 18% fat, she would need to lose only 7 pounds of fat, reducing her weight from her current 130 pounds to 123 pounds. Losing more than 7 pounds means losing lean body mass (usually metabolically-active muscle tissue), which is clearly not desirable.
So before you decide that you need to "lose weight", remember to consider that "weight" consists of both lean body mass and body fat. Try to keep your weight loss goals realistic, and remember, keep the calorie-burning muscle, and lose only the fat
For those of you working with me on losing weight, we have discussed body fat and maintaining muscle in detail. When the body experiences a decrease in caloric intake, it sheds both fat and muscle. As a result, the number on the scale will drop quickly, satisfying the client but not the body or the ultimate goal. Muscle comprises the machinery necessary to burn fat. If you lose this fat burning machinery, you will not be able to maintain the weight loss. One fact is true, women more so than men, who lose weight are more likely to lose an unhealthly amount of muscle mass if they are not weight training during their weight loss phase, and those who do not weight train are more likely to put the weight back on. Having your body fat measured will help us keep track of your fat and muscle loss and adjust your program if needed. Hydrostatic body fat testing is one of the most accurate way of measuring your body fat.
I will keep you posted when NPAC will be offering Hydrostatic Body Fat Testing.
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