Review

“…a comprehensive reference on body composition measurements and the scope of influence on physiology and pathology related to body composition.” — Journal of Dance, Medicine & Science (review of the first edition)”…indispensable for exercise science researchers who want to use the methods and fully understand the literature based on these methods.” — Rivista di Antropologia (review of the first edition)

Review

“…provides a comprehensive referen (more…)

Body Composition Scale

Whenever we embark on any type of fitness program, we expect to make some kind of progress.  Otherwise, we would just be wasting out time.  Measuring our progress is very important not only to let us know if and how quickly we are improving, but also because it provides encouragement for us to stay on track.  However, no measurement is perfectly accurate, and not all measurements are appropriate for every goal.  Using a measurement that is irrelevant to your goal is likely to provide meaningless or inaccurate information. As a result, we should make sure that the measurements that we take are appropriate for our goals.  The tools and measurements for monitoring progress can span the full range of indicators that measure health, physical appearance/body composition, and athletic performance.  However, we will stick to indicators of physical appearance and body composition because these are the ones that generate the most interest in health and fitness. This article will list some measurement parameters along with their objectivities, accuracies, and with synopses of their uses and limitations.  For the purposes of this discussion, the objectivity of a measurement is defined as the reading’s independence from individual interpretation.  For example, weight is considered to be very objective because if the scale shows your weight to be 145 lbs, it will do so regardless of what you want it to show.  Also, for the purposes of this discussion, the accuracy is defined as the ability to accurately indicate body composition such as fat percentage.WeightTheory: Heavier person is fatter.Objectivity/Accuracy: Very objective but very inaccurate When used by itself, weight gives no useful information on body composition.  However, when combined with percentage body fat measurements, it can be useful in estimating lean mass.  It can also be useful for athletes who compete in weight divisions (i.e. boxers).Body Mass Index or BMI (Weight in kg divided by height2 in meters)Theory: If 2 people are the same weight, then the shorter is fatter.Objectivity/Accuracy: Very Objective but very inaccurate BMI gives no useful information on body composition and it is useless for computing lean mass.  However, its convenience makes it useful for studies of a general population.Girth Measurements with a Measuring TapeTheory: Smaller girth (especially around waist) is leaner.Objectivity/Accuracy: Reasonably objective but slightly inaccurate Girth measurements do not directly measure body composition but they can tell you if your waist or hip measurement is expanding or shrinking.   Girth measurements are very convenient and are useful for monitoring trends.  In addition, using a measuring tape is the best way to see if you will fit into those new clothes.PhotographTheory: If you look leaner, then you probably are.Objectivity/Accuracy: Somewhat objective but somewhat inaccurate The results that you get from a photograph are affected by the lighting, the camera and even photographer technique.  However, if you use constant photography conditions, before and after pictures are very useful for measuring your progress.Buoyancy Measurement in a Flotation TankTheory: Muscle is less buoyant than fat.Objectivity/Accuracy: Very objective and very accurate Buoyancy measurement is the most accurate way to measure body composition on living subjects and is widely accepted as the gold standard.  However, it is inconvenient and it requires a high degree of technical competence from the tester.  Also, trapped gas can affect the measurement.  Regardless, it is the most accurate way to measure percentage body fat for purposes of estimating lean mass.Skin fold Measurements with CalipersTheory: The less you can pinch, the leaner you are.Objectivity/Accuracy: Reasonably objective and reasonably accurate Skin fold Measurements are second to buoyancy measurements in accuracy.  However, it only measures subcutaneous (below the skin) fat and it requires some technical knowledge by the person who is taking the measurement.  Generally, its accuracy increases with the number of places on your body that are measured.  It can be very useful because fat below the skin is usually what determines how well your abs are showing or how you look in a swimsuit.Bioelectrical ImpedanceTheory: Muscle conducts electricity better than fat does.Objectivity/Accuracy: Very objective but slightly accurate This measurement assumes average arm length for height, along with constant hydration and electrolyte levels.  Deviations in any one of these parameters can significantly affect the measurement.  However, it is convenient and easy to use. As mentioned before, we pursue fitness for a variety of reasons and there are a variety of methods for measuring our progress towards our goals.  Whether your goal is to fit into those new clothes, to look great for that photo shoot, or simply to feel better, it is important that the means of measuring your progress is relevant to your individual goal.

Body Fat Scale

Body Composition Scale – Anthropometric methods

There exist various anthropometric methods for estimating body fat. The term anthropometric refers to measurements made of various parameters of the human body, such as circumferences of various body parts or thicknesses of skinfolds. An excellent explanation of these methods is available in a PDF from the Academy For Educational Development.

Anthropometric Body Composition Methods Basis

Most of these methods are based on a statistical model. Some measurements are selected, and are applied to a population sample. For each individual in the sample, the method’s measurements are recorded, and that individual’s body density is also recorded, being determined by, for instance, under-water weighing, in combination with a multi-compartment body density model. From this data, a formula relating the body measurements to density is developed.

Anthropometric Body Composition Scales Measure Body Density Not Fat Percentage

Because most anthropomorphic formulas such as the Durnin-Womersley skinfold method, the Jackson-Pollock skinfold method, and the US Navy circumference method, actually estimate body density, not body fat percentage, the body fat percentage is obtained by applying a second formula, such as the Siri or Brozek described in the above section on density. Consequently, the body fat percentage calculated from skin folds or other anthropometric methods carries the cumulative error from the application of two separate statistical models.

These methods are therefore inferior to a direct measurement of body density and the application of just one formula to estimate body fat percentage. One way to regard these methods is that they trade accuracy for convenience, since it is much more convenient to take a few body measurements than to submerge individuals in water tanks.

Sampling Issues Affect Accuracy of Anthropometric Body Fat Percentage Measurements

The chief problem with all statistically derived formulas is that in order to be widely applicable, they must be based on a broad sample of individuals. Yet, that breadth makes them inherently inaccurate. The ideal statistical estimation method for an individual is based on a sample of similar individuals.

For instance, a skinfold based body density formula developed from a sample of male collegiate rowers is likely to be much more accurate for estimating the body density of a male collegiate rower than a method developed using a sample of the general population, because the sample is narrowed down by age, sex, physical fitness level, type of sport, and lifestyle factors. On the other hand, such a formula is unsuitable for general use.