The InBody Scanner

Bio-impedance body composition analysis

Excess adipose tissue (fat) can greatly increase your risk in developing chronic disease, such as cardiovascular disease, type II diabetes, stroke, cancer, sexual dysfunction, and metabolic syndrome.  The danger of excess adipose tissue is even more relevant in relation to the development of visceral fat, or fat that accumulates around the abdomen.  Fat cells that sit around this area alter the way the body operates.  The fat cells in this area have the capacity to switch on pro-inflammatory pathways, as well as activate signalling molecules that interfere with hormone balance.  Excess glucose (energy) from over-consumption of sugary junk foods, is stored as fat, and has a tendency to accumulate around the mid-section.  If the weight gain wasn’t enough, the un-orchestrated hormonal fluctuations also lead to increased hunger, further exacerbating the issue.

At present, there are several ways to examine body composition however, some come with several disadvantages.  Body mass index (BMI) is a gross measurement of relative weight and is calculated based on someone’s height and weight in kilograms.  It is often used in large population studies, as it does not take into consideration muscle mass and hydration levels.  Individuals may have a higher BMI (associated with increased obesity), however, muscle weighs more than fat; athletes often have a higher BMI despite have a high percentage of lean muscle mass. Waist circumference is another indicator of a healthy weight.  A waist circumference of equal to or less than 94 cm is considered healthy for men, and equal to or less than 80 cm in women.  According to Wells and Fewtrell (2006) a waist-to-hip ratio is independently associated with morbidity after adjustment for relative weight, such that the use of relative weight and body shape simultaneously gives a better estimate of morbidity than either alone.  Another old-age method of measuring body composition is via skin folds measurements using callipers.  Several equations are derived for the prediction of body fat percentage however accuracy varies plus or minus 9% (Wells and Fewtrell, 2006).

New research is proving that fat cells are more than just storage of extra calories.  Bio-impedance body composition analysis is a useful tool in not only determining the percentage of visceral fat accumulation, but also analysing lean mass and water percentage in the body.  Bio-electric impedance is a highly accurate method of determining body composition.  As stated by Wells and Fewtrell:

The generic theoretical model treats the body as a single cylinder, with measurements made between electrodes placed manually on the wrist and ankle. Adjustment of bioelectrical data for height allows estimation of total body water (TBW). In practice, this requires the empirical derivation of regression equations relating height2/impedance to TBW. These equations are then applied subsequently to predict TBW, which is converted to FFM (fat free mass)”.

In layman terms, a mild electrical current is sent through the body; this electrical current will travel through different body structures at differing rates, thus, calculations can be formulated which then measure adipose tissue, hydration levels, and fat free mass, or lean tissue (muscle percentage).

The Inbody Scanner

The InBody scanner is a newcomer and has been developed to overcome early limitations of bio-impedance analysis via the alteration of frequencies and segmental body measurements.  The InBody accurately analyses the total body composition by separately measuring impedance of the body trunk (torso), which accounts for nearly 50% of total body weight and has different cross-sectional measurements in comparison to the arms and legs.  The InBody has also progressed from the traditional single-frequency impedance to an updated multi-frequency impedance technology, allowing for more systematic and authentic results (InBody, 2017).  Other updated features that allow for more precise measurements include:

  • 8-point electrodes (measurements taken via both hands and feet); and
  • statistical variables, such as age and gender, are no longer required to deliver accurate results.

According to the company InBody Co. Ltd. (2017) the InBody scanner’s accuracy shows a correlation coefficient of 0.98 when compared against the DEXA scan, the current gold standard for body composition measurement.  A DEXA scan uses two x-ray beams with different energy levels to determine body composition and is mainly used to assess bone density.  A correlation coefficient determines the degree to which two variables are associated—the closer to 1.0, the stronger the relationship.

The measurement of body fat in relation to total body weight is an integral aspect of a complete health and wellness assessment. Body weight is simply a measure of how much weight someone is carrying but it does not give any information as to how much of that weight is made up of body fat and how much is made up of other body tissues. It is also important to know how body fat is distributed throughout the body because this can affect the risk of developing certain diseases.

The InBody scanner can provide measurements of both body fat percentage and also give an indication as to how this fat is distributed on the body. This information can help to more accurately inform a tailored weight management plan as well as identifying increased risk of other diseases. Any information regarding increased risk of disease can then be used to aid appropriate preventative treatment protocols.

 

References

Wells J & Fewtrell M. Arch Dis Child. Measuring body composition. July 2006; 91(7):612-617. Doi: 10.1136/adc.2005.085522.

Cheng MF, Chen Y, Jang T, Lin W, Hsieh K. Biol Sport. Total body composition estimated by standing-posture 8-electrode bioelectrical impedance analysis in male wrestlers. Dec 2016;33(4):399-405. Doi:  10.5604/20831862.1224097.

InBody Co. Ltd. (2017). Retrieved from https://www.inbody.com/global/intro/Technology.aspx March 2017.

 

 

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