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Why measure Body Fat at all?

Percent body fat is known to be a key factor in determining health and fitness.

Nutritional status is also determined by the measurement of lean muscle mass, and a decrease in lean muscle mass can lead to a state of malnutrition or even diabetes.

Measuring total body weight alone is not a reliable measure of health as it will not distinguish between fat weight and muscle.

For example, the total body weight of a body builder with heavy muscle, and an overweight obese person could be virtually the same, although their state of health is obviously very different.

Carrying too much fat is what makes a person obese, not the weight shown on the scale. Obesity is a known risk for many serious medical conditions including heart disease, diabetes and even certain forms of cancer. Obesity contributes to at least half the chronic diseases in western society. However, it is not weight that needs to be reduced, rather the amount of body fat a person has.

How does Bodystat measure Body Fat?

Bio-electrical Impedance technology works by running a small current through the body, measuring the resistance and reactance to the flow of the current. This data is then processed in the device along with the height, weight, gender and age of the subject. The results for body fat, lean weight and fluid status are then displayed using the measurement and input data.

How are the calories calculated?

The calories are calculated depending on the gender, age, weight, height and exercise level entered in to the device. Unlike other calculations, we use the lean weight, which is the metabolically active tissue; therefore, we feel that this provides greater accuracy.

What is the difference between the Basal Metabolic Rate and the Estimated Average Requirement?

The Basal Metabolic Rate is the number of calories required in a day when at rest and the Estimated Average Requirement is the number of calories required when active.


What ages can I use the devices on?

All Bodystat devices are automatically programmed to measure adults between the ages of 18 to 70 years. The Bodystat 1500MDD, QuadScan 4000 and MultiScan 5000 also include a children’s equation for 6-17 years. Alternative equations are available in our software programs for athletes, COPD and over 70’s.

Are there any patients I shouldn’t measure with this device?

As with all BIA devices we recommend that you do not use on patients who have an implanted cardiac device such as a pacemaker or who are in the early stages of pregnancy.


Can I re-use electrodes?

Electrodes are only for single use. The electrode gel pick up skin oils, debris and hair which reduce the efficacy of the electrode. Re-using the electrodes will affect the accuracy of the measurements obtained and is also unhygienic.
Can I use alternative electrodes other than Bodystat?

Bodystat ensures that we use the highest quality electrodes with our devices and these are tested for accuracy and reproducibility. Bodystat cannot guarantee the accuracy or reproducibility of measurements should other brands be used. In particular with multiple frequency measurements which require a longer size electrode in order to measure at small and high frequencies.

Does the size of the electrodes matter?

Yes! But only if you are using our Bodystat 1500MDD, QuadScan 4000 and MultiScan 5000 dual or multi-frequency devices. Our dual and multi-frequency devices require a larger surface area to conduct the current and to get the most accurate reading. Using a smaller electrode on these devices can affect the accuracy of the measurement.

Can a test be performed by placing electrodes on left side?

YES, we suggest the right side only because the heart is on the left side which will increase the resistance. NOTE: If the left side is selected, they must always use the left side for that patient – this is because impedance values will be slightly higher compared to the right side, due to the heart increasing the resistance on the left.


Do metal implants such as knee, shoulder and hip replacements alter the measurements?

In day to day clinical application, implants do not have a significant impact on the measurements obtained by BIA. The key to obtaining useful information from BIA devices is to take a bench mark measurement and to track change over a period of time.

Do silicone implants effect the measurements?

This has yet to be researched fully, but it is generally thought that implants do effect the results. Although you would still be able to track the change in the results of your client.

What is the impact of entering the wrong height?

Entering an incorrect height into a measurement can affect the accuracy of the results. If the subject is still in the measurement position, it would be recommended to repeat the measurement as quickly as possible.

What is the effect of nude weight and clothed weight?

The weight that you enter on the device is critical. If this is inaccurate then the results you will achieve will be inaccurate.

Can you feel the test while it is being performed?

No, the current passed through the body is so small, it is impossible to feel!

Will very dry or very oily skin affect the readings?

It can, very good contact between the skin and electrodes must be made. If the person’s skin is oily, then wipe with an alcohol swab before positioning the electrodes.

Do any medications affect the reliability of the test?

Certain Steroid based medication may affect the test results.

Will jewellery affect the test?

No, as long as it is located in one spot (i.e., bracelet, necklace), and does not interfere with electrode placement.


What is the best time of day to measure a patient?

As with weighing yourself, it is best to be consistent and measure around the same time of day, each time you carry out a test.

Can my patient sit during measurement?

Measurements are best performed with patient in a relaxed, supine position. If the subject is unable to lay down for medical reasons, then the subject may also sit during the measurement process. However, the feet should be raised, limbs should be straight and not touching in order to achieve an equal distribution of fluids.

How often should I perform the test on my clients?

We would recommend that the first test is done at the beginning of the treatment or programme and then followed up by tests at regular periods. In the case of fitness this would be 4-6 weeks and in the case of medical applications, such as lymphodema, this would be on the patient’s regular check-up visits.

What are the pre-test protocols prior to testing?

For accurate and reproducible results on repeat tests, it is important that the subject is as normally hydrated as possible. The following guidelines should ideally be followed wherever possible.

  • No eating or drinking 4 to 5 hours prior to the test
  • No exercise 12 hours prior to the test
  • No alchohol or caffeine consumption 24 hours prior to the test.


How can I make sure that the results are accurate when repeated?

In order to ensure that the results are accurate when they are repeated it is important to make sure that the electrodes are placed in exactly the same place as they were for the previous test. Two electrodes are placed on the foot and the hand as illustrated below. In order to obtain accurate data you must follow the instructions on test protocol. Electrodes should be re-used and must not be cut in half.

The red lead is always connected to the electrode closer to the nails, and the black electrodes at the back.

Bodystat 1500 Electrode Placement

Bodystat 500, 1000, 1500MDD, QuadScan, MultiScan Electrode Placement

How can I improve measurement quality?

Ensure patient is relaxed in the supine position, ensure skin is clean and good electrode contact has been achieved. Check correct electrode placement and check correct connection of patient lead. Try to minimize sources of electrical disturbances (power sources, mobile phones etc.) Ensure legs are apart and arms are not in contact with the trunk.

How do I check the measurement accuracy following a test?

With our dual and multi frequency units, it is recommended that the raw impedance data be viewed following the measurement. Each value must be lower than the previous impedance value. If one of the values seems incorrect or higher than the previous value, then the test may need to be re-taken.


Frequency Khz550100200
Impedance Values (Ohms)588505475454


How can I use the data gathered?

The data gathered may be either printed out and given to the client or may be entered in to the computer software. This software then enables you to build a profile of your client, which is a useful way to motivate them towards their goals or track any trending or change over time.

Are the any leaflets or posters that will help me explain Bodystat® and body composition to my clients / patients?

These are available directly from sales@bodystat.com.

Where can I get training from to use my Bodystat?

Training is generally not required for Bodystat devices as they are very easy to use and the electrode site placement is reproducible. Should you require training you may wish to contact the organisation that you purchased the device and they may be able to assist you. Additionally, there is also a series of training videos available. If you are unsure, then please contact support@bodystat.com


Do I have to input hip & waist measurements?

These are not essential for the body composition results and are only required for the Waist/Hip ratio. If you do not wish to have these measurements on your machine, you may remove these by selecting ‘omit’ in the installation mode.

How do I categorise the level of fitness (activity level)?

The activity level does not affect the actual body composition results but is only used to calculate the EAR (Estimated Average Requirement for Calories). The Basal Metabolic weight is calculated on the LEAN weight of the individual.

Very Low – Generally inactive

Low/Medium – Recreational activities for short during and at low intensity

Medium – Sporadic involvement in recreational activities for short duration and at moderate intensity.

Medium/High – Moderate job activity and moderate exercise 3 times per week.

Very High – Consistent job activity and vigorous exercise 4 times per week.

I don’t like using metric measures can I change this?

Yes – simply go to the installation screen and select your preference.

How long does it take to perform a test?

The test is complete within a couple of seconds.

How do I know if my device is working correctly?

You can check the accuracy of the device by checking the calibration. Refer to the trouble shooting guide for the calibration procedure. We do also recommend using a subject whose body composition does not fluctuate greatly and remains fairly constant as another independent check.

How often should I check the calibration of the device?

This depends of the frequency of use. If the device is being used on a daily basis then we would recommend once a week.

How do I check the calibration of my device?

This can be done by attaching the leadwires to the metal prongs on the blue plastic calibration block. Switch the device on and run a test as normal. Within the results the impedance in ohms, should read between 496 and 503.

How do I access the installation mode of the device?

The installation mode allows the user to change parameters such as metric or imperial options, display options, etc.

Non touch screen devices

Hold down the up arrow whilst switching the device on at the same time. A message will appear displaying “installation mode”. Release the up arrow and the first screen displayed will be language. Press the enter button to scroll through the options. Once you have amended any options, a screen will be displayed asking if the “installation is complete”. Change this option to yes and press enter and a message will appear confirming that your parameters have been stored.


How do I access the serial number of the device?

The serial number is a six digit number shown on the reverse of the device and can also be accessed on the device itself.

Non touch screen devices

Hold down the down arrow whilst switching the device on at the same time. The version number of the device will be displayed, followed by the serial number.

Touch screen devices

Switch the device on and the home screen will be displayed. The serial number can be accessed by selecting the information button from the home screen.


What is reactance, resistance and impedance?

Impedance defines the opposition to an alternating electrical current. Impedance is comprised of both resistance and reactance. By analysing the resistance and reactance of human tissue certain properties of the tissue can be obtained. The resistance of the tissues to the electrical current determines the opposition of the tissue to the flow of electrons (dissipative loss). It is related to the amount of water present in tissues. The reactance by contrast reflects the capacitive losses caused by cell membranes.

What is phase angle?

Phase Angle is the direct measurement of the integrity of cell membranes and how well they function. When illness or malnutrition is present, the voltage of the cell changes, which alters the capacitance of the cell membrane, and ultimately the Phase Angle.

It is important to note that every individual will have their own ‘normal’ Phase Angle, and what might be a low value for one person, could be a completely normal value for another. So use the individual as the control and monitor change over time to track recovery of illness or use as a preventative marker before onset of illness occurs. Bodystat is unique in that we MEASURE Phase Angle rather than calculating Phase Angle providing a more accurate assessment of health.

What is BIVA?

The BIVA graph plots the resistance and reactance at a fixed frequency of 50 kHz on an RXc Graph. The position of the dot reflects the subject’s health status in comparison against a selected population group.


My device displays “Faulty Electrode Check Connection” error message when trying to perform a test?

Faulty electrodes indicates that there is an error in the connection when the measurement is being undertaken. If this is the first time that the message has been received, check the electrode placements on the subject to ensure that they are in place and that the crocodile/alligator clips are attached correctly. Ensure that the leadwires are also firmly pushed into the rear of the device. Once complete, try to perform the test again.

If the faulty electrode message appears again, then we would recommend checking the calibration of the device (following the calibration procedure detailed in the device questions). If the message appears on the calibrator, then this could indicate that there is a problem with either the device or the leadwires. Firstly, we would recommend that you check the batteries in the device and ensure that only Duracell batteries are being used. If the batteries are low, then replace with new Duracell batteries and check the calibration again. If the error continues, then contact your local dealer or Bodystat head office <support@bodystat.com> for further support.

Check list:

  • Ensure that the electrodes are correctly positioned and firmly in place.
  • Electrodes should not be used more than once and should not be cut in half.
  • If the electrode is not firmly positioned due to cream on the skin, then remove the electrode and wipe the skin with an alcoholic wipe. Replace with fresh electrodes.
  • Ensure that the crocodile/alligator clips are attached correctly.
  • The black clip must be connected to the wrist and ankle and the red clip must be connected to the electrode nearest to the fingers and toes.
  • Ensure that the Bodystat device is using Duracell batteries only.
  • Ensure that the patient is lying in the correct position and remains still during the testing process.
  • Ensure that there is no static nearby, e.g. the carpet
  • If the device remains with a faulty electrode connection
  • Check the calibration
  • Check to ensure that the leadwires are not being wrapped around the unit
  • Contact Local dealer or Bodystat for further assistance.



The Figure below provides a graphical representation of the relationship of mass and water distribution.


All bodies contain fat. It is located largely under the skin, but its presence is distributed throughout other tissues and in cell membranes. It is essential for life that we contain a minimal proportion of body fat. Most people, however, have large amounts of fat acting as stores of energy.

Typical fat: women (30 years old) 20-25% of body weight. Men (30 years old) 15-20% of body weight.



FFM and Lean Body Mass (LBM) are often used interchangeably and are quite close in some definitions, but they are not always equivalent depending on how they are derived. FFM represents all the gross chemical composition of the body apart from organic solvents soluble and extractable lipids (fat). It includes all water, protein and mineral and miscellaneous others such as urea, RNA, DNA, glycogen etc, i.e. it is a chemical definition. Nowadays most authorities use this term because it is a firmer definition. It is the sum of BCM and ECW and consists of muscle, bone, minerals and other non-fat tissue.


Refers to losses of intracellular water that ultimately causes cellular desiccation (drying up) with resulting elevated plasma sodium concentrations and osmolality.


The total amount of fluid in the body whether in cells, outside cells, in blood etc. Since most of the body water is contained in the Lean Body Mass, the body water percentage will increase with a loss of fat weight and a gain in lean tissue.

Typical values: Women 50-60% of body weight. Men 55-65% of body weight.

These values vary with hydration state, pregnancy, menstrual phase, aging etc.


The non-metabolising fluid surrounding cells that provide a medium for gas exchange, transfer of nutrients and excretion of metabolic end products. It is ~ 94% water by volume, is distributed into 2 main compartments: plasma in the intravascular space and interstitial fluid in the extravascular space.


Those components of total body water located within cells (ICW) and outside cells (ECW)


The dry lean weight is the Lean Weight excluding water (muscle and bone).


Rate the body burns energy (in calories) during a normal resting state, over a 24-hour period to maintain essential body elements e.g. body temperature, heartbeat, brain, lungs. This is the minimum amount of energy required to keep a person alive. BMR is based upon an individual’s Fat Free Mass. The greater the BMR per kg of Body Mass, the faster the body will consume excess calories. Regular exercise may assist in increasing BMR.


The estimated amount of energy a body requires during a 24hour our period to maintain its present body composition status for a required activity level.


The BMI is a simply determined and widely used measure of body status. It is largely independent of underlying body frame size.

BMI (kg/m2)= [body weight (kg)] / [body height (m)]2

Reference ranges:

            Underweight                                       <20

            Normal weight                                    20-25

            Overweight                                         25-30

            Obese                                                  >30



Body Fat Mass Index is similar to BMI except that it looks at the volume of fat in the body in relation height squared.


Fat-Free Mass Index is similar to BMI except that it looks at the volume of Lean Weight in the body in relation height squared.


The total mass of cells in the body comprising the metabolically active tissue. It is a component of LBM or FFM.


The ratio between Extracellular Water and Total Body Water. The measurement of TBW is of limited value in the nutritional assessment of some seriously ill patients. Patients with trauma or sepsis may retain fluid in response to nutritional support and weight gain may simply reflect an expansion of the extracellular water space. Such weight gain cannot be considered as an improvement in nutritional status as it does not reflect an increase in protein stores. A more useful assessment of nutritional status in these patients may be obtained from separate estimates of ECW and TBW.


The waist to hip circumference is an indication of the distribution of body fat. Where waist circumference equals or exceeds the hip circumference, there is growing evidence to show that the risk of chronic heart disease increases significantly.

High risk ratio for males        1.00 and higher

High risk ratio for females     0.80 and higher


The Prediction Marker or Impedance Ratio is the ratio between the impedance measurement at 200 kHz and 5 kHz. The Wellness Marker is the Impedance ratio between the impedance measurement at 50 kHz and 5 kHz. The objective of Bodystat’s unique Prediction or Wellness MarkerTM is to provide health professionals with a tool for early detection of cellular change before it becomes clinically obvious. By combining the information obtained from the measurement of body fat, fat-free mass and the Prediction or Wellness Marker, even malnourished obese subjects may be identified. There is always a danger that high levels of body fat may obscure an underlying serious illness developing, such as cancer or other wasting diseases. By monitoring an individual’s unique Prediction or Wellness Marker it may be possible to detect the advent of a potentially serious medical condition. Healthy individuals with good cellular status tend to have a lower Prediction or Wellness Marker while the unhealthy have higher values. The lower the marker, the healthier and more hydrated the body cells; the higher the marker, the less healthy. Bodystat’s unique Prediction and Wellness Marker is specifically designed to quickly and non-invasively assess overall cellular health status and the earliest signs of cellular malfunction.


Impedance is the pure opposition to the flow of an alternating current produced by the capacitant effect of cell membranes and tissue interfaces. Since the fat-free or lean tissues have a high proportion of water and electrolytes they are a good current conductor, whilst the fat mass has a high resistance and is essentially non-conductive.


Reactance results from the additional opposition to the flow of an alternating current due to the capacitive nature of cell membranes.


Resistance is the pure opposition to the flow of an alternating current produced by the capacitant effect of cell membranes and tissue interfaces. Since the fat-free or lean tissues have a high proportion of water and electrolytes they are a good current conductor, whilst the fat mass has a high resistance and is essentially non-conductive. Resistance is inversely proportional to body water and fat-free tissue mass. Since measured resistance is also dependent upon the cross-sectional area of the conductor, biological resistance is dominated by that of the extremities i.e. the limbs.

Impedance/Resistance/Reactance/Phase Angle Relationship
Biophysically, the human body represents a network of resistors and capacitors with the extracellular and intracellular fluids acting as resistors and the cell membrane as a capacitor. The Impedance (Z) is composed of two vectors, Resistance (R) and Reactance (Xc). The angle between these two vectors is called phase angle, which is dependent on the number of cells, cell size, membrane permeability, and the distribution of body fluids. At high frequencies Xc is a relatively small component and the impedance is numerically close to the resistance; the two values are identical at infinite frequency.


Phase Angle is a measurement at 50 kHz relating to the function & integrity of the cell membrane and thus overall cellular health.

Phase Angle is made up of two components: resistance (fluid) and reactance (body cell mass). The higher the Phase Angle the healthier the cells. The Phase Angle records the voltage drop in an applied current.  The voltage drop is larger if the reactance (ie the ability of the cell to react with the current) is larger which only occurs in a healthy functioning cell membrane.

The expression for the phase angle φ is:

φ = arctg X/R, where resistance is R and reactance is X.

Phase Angle has been found as a useful prognostic indicator of ill health such as malnutrition, cancer and other potentially serious diseases.


BIVA is a method of interpreting the data obtained from some Bioelectrical Impedance Analysis devices. It is a quick, simple, pictorial way of discovering the hydration and nutritional status of the subject in comparison to their population group. It establishes where your client is in reference to their demographic.

BIVA stands for Bioelectrical Impedance Vector Analysis and is sometimes referred to as the ‘RXc graph’. It simply uses the Resistance (R) and Reactance (Xc) at 50kHz and is normalised to the subject’s height (not requiring the subject’s weight). Once the measurement is performed, the subject’s results are illustrated in the form of a dot on the vector. The position of the dot then reflects the subject’s health status (lean mass and hydration) in comparison to the subject’s chosen demographic group.

Graphical Representation

The subject in the graph is illustrated by a dot. The desired outcome for a physician is a dot within the 75% tolerance of the statistic distribution of the chosen demographic group.

The vector line indicates the Vector Length. The shorter this line the more fluid overload or oedema is present and the longer the line illustrates dehydration.

Consideration is then given to the angle of the vector. The steeper the angle the more athletic or obese the subject is, whereas a shallow angle reflects malnourishment or anorexia.


Please download the relevant software info.


Instructions to Download BIAS BIS Software for the Bodystat 1500.


Instructions to Download BIAS BIS Software for the Bodystat 1500MDD.


Instructions to Download BIAS BIS Software for the Quadscan 4000.


Instructions to Download BIAS BIS Software for the Multiscan 5000.