Frequently asked questions and answers related to the ELG Health Management System and bioimpedance technology


  How does bioelectrical impedance analysis work?

  Bioelectrical impedance technology measures conductivity (ohms) of the body. The method is based on the fact that the lean tissue of the body is much more conductive due to it's higher water content than that of fat tissue.
A bioimpedance meter is attached to the body at the extremities (hand and foot) introducing an 800 micro-amp / 50 kilohertz signal that measures the body's impedance.
  In simple terms, the more lean tissue present in the body, the greater the conductive potential.

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  What variables cause prediction errors in testing?

  Any event which will alter the clients "actual" weight such as eating a large meal (increase weight) or heavy exercise (decrease weight as well as dehydration) can alter readings.
  Some drugs (such as diuretics and certain hormone drugs) can abnormally and dramatically reduce total body water and thus reducing scale weight.

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  What kind of battery do the ELG bioimpedance meters use? How do you change the battery?

 The ELG, ELGII and ELGIII use a standard 9-volt battery. The battery should be replaced approximately every 500 tests. It is recommended to use a high quality alkaline battery. Rechargeable batteries are not recommended.
  The black "feet" in the four corners of the bottom of the ELGII have Phillips head screws and fasten the case together. These screws need to be removed to open the back of the unit.
  Inside the unit is a standard 9-volt battery. Simply slide the used battery out and replace it. Make sure to match the "+" terminal to the "+" receptacle and "snap" the new battery in firmly.

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  Why is body composition more important than weight?

  Body composition is the true definition of an individuals weight status. Scale weight alone does not necessarily mean an individual is lean or fat. Lean mass (muscle) actually weighs more than fat tissue, therefore an individual with large amounts of lean mass will have an "elevated" scale weight while they are not over fat. Focusing on losing fat and maintaining or increasing lean is a much healthier way to increase longevity and weight loss.
   Only body composition analysis can determine how much muscle and fat are lost or gained as the result of any nutrition, exercise or pharmaceutical program. Low calorie "quick fix" weight loss plans actually cause an individual to lose lean mass, and do not include lifestyle changes, which are important method involved in permanent successful weight loss.

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  What is the accuracy (Standard Error) of the ELG analyzer?

  The Standard Error of Estimate (SEE) for the ELG is +/- 2.8% when compared to the criterion hydrostatic tank. See the validity study.

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  Why is the ELG more accurate than skin calipers?

  • Skin fold calipers assume that 50% of an individuals body fat is under the skin and 50% is inside the muscle. This is not always true and can create gross errors.
  • Skin fold calipers only "open" about 2 inches thus can not be used on obese people.
  • Test-to-test measurements (accuracy) vary from technician to technician and may fluctuate as much as 5%.
  • Skin fold readings can not detect changes in "lean mass".


  What is the significance of Total Body Water?

  Total body water is one of the predicted values (in addition to lean and fat mass) of the ELG Health Management System. Total Body Water is a major component of body composition and is factored into our patented algorithm.
  A single test of total body water, however, does not determine "hydration status." Total body water can be used in serial comparisons to determine changes in water volume and as a basis for discussions on fluid replacement.

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  What is the result of too few calories and/or excessive exercise?

  Researchers agree that when we consume less than approximately 50% of the total energy requirements, the body is placed into a state of "semi-starvation". Many popular diet plans even place the body into a "starvation" state in order to facilitate weight loss. 
  When the body is placed into a state of starvation, the biological and physiological response is to save energy in the form of calories (body fat).
In humans this means to slow down metabolic functions and use lean mass as a primary source of energy.
  When this occurs, either by caloric restriction or excessive energy expenditure (excessive exercise) the body will use existing muscle as a fuel source and conserve fat. Body fat is the "long term" source of energy for metabolic functions.

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  Why is an ELG test usually performed on the right side of the body?

  Every person has "functional" limb length differences. Because the BIA (ELG) technology is based on a "volumetric" principal, the length of the conductor is important.
   While acceptable results of body composition may be obtained for the majority of clients, standardizing test protocols such as consistent electrode placement is always emphasized to obtain reproducible results.

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  Is the test safe for someone using a pacemaker?

  An ELG test can be performed on any individual. The signal used is undetectable and completely safe. However, a newly developed cardiac device called an implanted defibrillator has not been tested and clients with the implant should not be tested.

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  Are the results accurate for pregnant women?

  Many physiological changes occur during pregnancy. Research has shown that changes in body composition can be monitored accurately. However, during the last part of pregnancy (third trimester), large amounts of lean body mass accumulate. These changes are not attributed to increases in muscle in the mother, but are increases in fetal development and amnionic fluids. Therefore testing up to the third trimester is safe and accurate, however, around the 5th to 6th month of the pregnancy the results show dramatic increases in the lean mass from the fetus and amniotic fluids.

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  Can I perform an ELG test on a child?

  The ELG Health Management System has been validated on subjects to 8 years of age. While the system will "predict" body composition values at any age, BioAnalogics has not been successful in establishing criterion values on subjects less than 8 years old.

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  Can I perform an ELG test standing up, or sitting down?

  The ELG test may be performed in either a lying (supine) or standing position. Always have the legs separated and do not allow the hands to touch the body. The body should be relaxed. The test should never be performed while the client is sitting down.