Thursday 27 September 2012

Assessing Body Composition

Not a good way to monitor your body  composition
When it comes to good training and eating, it is important to be results based. Tracking body composition can be very helpful. After all, if you are going to invest your valuable time and energy into training and eating right, you want to know that you are getting results for your efforts. Most people make the mistake of just standing on the bathroom scale - which really does not give you the whole picture. If your weight goes down, was it fat, muscle or water? If your weight goes up, did you gain muscle or fat?After all, we want fat loss or muscle gain, not necessarily just weight loss or weight gain. Here are some of the main ways to assess your body composition.

Important note: for some people, body composition assessment can lead to body image problems, self-esteem issues and eating disorders. If you are at all concerned about doing this, I would leave it. Look at other measures of health and fitness (e.g. gym performance as recorded in your training log, health measures from tests such as blood work, blood pressure, etc).

Dual-Energy X-Ray Absorptiometry (DEXA)
This devise has a computer which measures absorption of photon beams into bone mineral and soft tissues to analyze body composition.
Pros: considered to be the most accurate, often consider the current "gold standard"
Cons: expensive, not practical or easily accessible

Hydrostatic Weighing
With this method, you estimate body composition from land vs. water weighing in a dunk tank. This allows you to calculate body density and determine body fat percentage from that.
Pros: previously considered the "gold standard", still very accurate
Cons: expensive, not practical or easily accessible, not good for those who fear being under water and breathing all the air out of your lungs.

Air Displacement Plethysmography
Similar to underwater weighing, but no water. You sit in this chamber often called a Bod Pod and it measures air displacement to estimate body density and thus calculate body fat percentage.
Estimates fat from estimated total body volume
Pros: very accurate, more practical and easy than hydrostatic weighing
Cons: expensive, not easily accessible, not good for those who are claustrophobic.

Skinfold Measurements
Measure skinfolds at different spots and plug into a formula to estimate body composition.
Pros: relatively inexpensive and practical, allows progress monitoring at different sights which may correlate to various hormonal levels.
Cons: tester experience, testing errors, invasive, only measures subcutaneous fat, hard to find an appropriate place to have this done.
Note: this one really depends on the skill of the tester.

Bioelectrical Impedance Analysis
Computer estimates body composition based on impedance and other variables
Pros: relatively inexpensive, accessible, no skill required, non-invasive
Cons: low accuracy, easily changed by testing conditions (e.g. hydration), not appropriate for those with pace makers.
Note: if you use this, be sure to re-test under the exact same conditions to improve accuracy.

If you really want to know your exact body composition, then one of these methods can be used. Besides the biolectrical impedance, all of the other ones are going to be harder and more expensive to do. If you can access a competent trainer who has experience with skinfold testing, then that can be an option. If you live near a university which has a lab with one of the above devises, they may offer body composition assessment to the public for a fee. If none of these methods work well for you, don't worry, I'll show you another much more practical way to monitor your body composition changes in my next post...

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