Using smart scales to measure your body composition can help you reliably and cost-effectively track changes if the measurement remains at a consistent level. These scales have the ability to send the electrical current up one leg and down the other leg.

Before using, users must set their age, height, and sex. Also called hand-to-hand impedance devices, they measure arm and upper trunk bioimpedance.

These common BIA devices are composed of four electrodes, each of which are placed on half of the body left or right , sending a current from the arm through the body and down the leg.

The Direct Segmental Multi-Frequency BIA or DSM-BIA is the most advanced, and also the most expensive, device providing bioelectrical impedance analysis. This device divides the body into 5 segments and independently measures the impedance for each segment. Bioelectrical impedance analysis BIA remains a quick and safe method for estimating body composition in adults.

This is why this cost-effective alternative is widely used in clinics and in sports medicine and other health-related fields. Many research efforts are yet to agree on a standard that can help correct the remaining questions of interpretation bias when using the BIA method.

However, consistency in measurements accurately helps to detect variations, which makes it easy for anyone to track changes in body composition. Continue without accepting Before you continue. We use cookies to offer useful features and measure performance to improve your experience.

Your preferences can be edited at any time. Find more information in our cookie policy. Essential cookies. Analytical cookies. Social media cookies. Marketing cookies. View details Accept selected. About bioelectrical impedance analysis and body composition measurement Bioelectrical impedance analysis or BIA is a simple and non-invasive test measuring how low-voltage electric currents circulate through the body with the help of electrodes.

BIA: a way to assess your body composition Because BIA helps to distinguish how body fat , muscles, and body water are distributed in your body tissues, it is widely used to determine your body composition. Therefore, BIA can be a critical assessment of your health. What is bioelectrical impedance analysis?

Where does bioelectrical impedance measurement come from? How does bioimpedance indicate body composition? How accurate is bioelectrical impedance analysis? TANITA Multi-Frequency Monitors are able to measure bioelectrical impedance analysis at three or six different frequencies.

The additional frequencies provide an. exceptional level of accuracy compared to single and dual frequency monitors.

The lower frequencies measure the impedance external to the cell membrane. The higher frequencies are able to penetrate the cell membrane. By measuring impedance at both the lower and higher frequencies it is possible to estimate extracellular water ECW , intracellular water ICW and Total Body Water.

This information is essential for providing the health status of a person and indicating health risks such as severe dehydration or oedema.

TANITA body composition monitors with Advanced Dual Bioelectrical Impedance Analysis Technology use two different frequencies to capture your body composition data. By using different frequencies, a higher accuracy of measurements can be achieved.

TANITA continues to offer the most accurate calculation of fat, lean mass or muscle and bone mineral density available, but with 4C monitoring we go even further, giving an unparalleled, 4-Compartment measurement.

Our new 4C method will enable you to fully assess levels of body fat, protein, bone mineral mass and water within the body. The 4C model divides body weight into fat, water, mineral, and protein using the gold standard method for measuring each element. The 4C model involves the measurement of body mass or weight, total body volume air displacement , total body water D20 , and bone mineral DXA ; however, specialised laboratory equipment is required minimising the availability of the 4C method to many clinicians and researchers.

Metabolic Sensing - Learn the Metabolism in Health, Dieting, Beauty, Medicine and Brain. CMC Publishing Co. The store will not work correctly when cookies are disabled. Consumer scales For Professionals Understanding your measurements Mini scales Support Blog About TANITA.

Home Bioelectrical Impedance Analysis. Fat is more resistant than muscle or water, so the higher the resistance, the higher the body fat percentage calculation is likely to be.

Most scales measure an estimate of your total fat, muscle, water, and bone in weight and percentage. Based on that rate, a calculation is used to estimate fat-free mass. The device then uses other data such as your height, gender, and weight measurements to determine your body fat percentage. There are different types of BIA devices, but each requires two contact points.

On a handheld device, the two points are your two hands called hand-hand BIA. The two contact points on a typical BIA scale are your two feet called foot-foot bioelectrical impedance analysis.

This means that when you use the device, you place each foot on a pad, and the current travels through your body between your feet.

There are also hand-to-foot BIA devices, as well. Many of the newer models of BIA scales link with a smartphone app so you can track your progress over time.

The price of your BIA scale will depend on how sophisticated the product is. Some scales use more than one frequency and more advanced algorithms to provide a result.

And some offer segmental fat analysis, meaning you can get body fat measurements for each leg, arm, and belly. Some experts say that segmental fat analysis using hand-foot BIA is more accurate because hand-hand devices primarily measure the upper body, while foot-foot scales primarily measure the lower body.

Bioelectrical impedance analysis devices are considered safe for most people. However, BIA should not be used by anyone with an electronic medical implant, such as a heart pacemaker or an implantable cardioverter defibrillator ICD. Also, most device makers recommend that pregnant people not use the products.

Some studies showed that bioelectrical impedance analysis is a reasonably accurate method for estimating body fat. But these research studies generally do not test the scales you find in the store. Experts generally agree that the accuracy of the measurement depends, in part, on the quality of the device.

In addition, other factors may affect a reading when you use a BIA scale. Some researchers also say that ethnicity can affect the accuracy of BIA measurements. Overall, studies show that this method is not very accurate although it may be able to track change over time, your results are unlikely to reflect your actual body composition.

Even if you get an accurate reading on a bioimpedance scale, the number represents an estimate of your total body fat percentage.

Bioelectrical impedance analysis does not accurately measure your total body fat. Most scales also cannot tell you where fat is located on your body. Even though many factors can affect your reading accuracy, a regular BIA scale can show you changes in your body fat over time.

The actual number may not be perfect, but you can still track changes to your body composition. Because many BIA scales offer several features for a reasonable cost and are a quick and easy way to estimate body fat percent, body fat scales that use bioelectrical impedance analysis are a worthwhile investment for consumers who are curious about their body composition.

Keep in mind that they are not likely to be very accurate but you can use them to track changes over time. Using another method of tracking your body composition can help you get a better picture of your actual measurements. It's also wise to understand that there is more to health than your body fat percentage or weight, and these scales are only a tool, not a reflection of your general wellness.

Gagnon C, Ménard J, Bourbonnais A, et al. Comparison of Foot-to-Foot and Hand-to-Foot Bioelectrical Impedance Methods in a Population with a Wide Range of Body Mass Indices. Metab Syndr Relat Disord.

Impedance comprises both resistance and reactance:. The small electrical current is passed through the body from conductive surfaces or electrodes. Conductivity is higher through fat free mass which includes muscle, bone and water than through fat mass which contains very little water.

Different body components have varying levels of impedance in response to different frequencies of the electrical current. Output is commonly provided in the form of an impedance value expressed in the unit Ohms, Ω; approximate range between Ω - Ω.

Interpretation of the impedance value varies by BIA instrument type. For single frequency BIA, the impedance value is interpreted as resistance R. For multi-frequency BIA and bioelectrical impedance spectroscopy, two values are provided, one for resistance R , and one for reactance Xc.

The impedance value is related to the volume of a conductor the overall body size and the square of the length of the conductor a distance which is a function of the height of the participant. BIA is used to assess the dimensions shown in Table 1, depending upon the type of instrumentation used.

The types of BIA instrument are described in more detail in the section below. Table 1 Anthropometric dimensions which can be assessed according to BIA instrument type. Bioelectrical impedance analysis BIA instruments use contact electrodes that send the electrical signal through the body.

These electrodes are either patch types similar to ECG electrodes or stainless steel plates. BIA instruments can be broadly classified into three types: single-frequency BIA SF-BIA ; multi-frequency BIA MF-BIA ; bioelectrical impedance spectroscopy BIS. Some BIA systems are incorporated into digital electronic scales, simultaneously measuring impedance and body weight with a force sensor.

SF-BIA frequency of 50 kHz also known as tetrapolar impedance is the most commonly used BIA instrument, based on 4 contact electrodes 2 injecting and 2 sensing electrodes.

The impedance is then used together with other anthropometric data, age and gender to predict body composition variables using empirical linear regression equations. SF-BIA is unable to distinguish the distribution of total body water into its intracellular and extracellular components.

MF-BIA frequencies up to kHz allows differentiation of intracellular and extracellular components of total body water. It relies on the principle that the body's impedance is dependent on the frequency of the alternating current applied.

Total body water is distributed between the intracellular and extracellular components, separated by cell membranes. Cell membranes act as capacitors that insulate the intracellular water ICW at low frequencies so that predominantly extracellular water ECW is measured.

At higher frequencies, the membranes are permeable to the current, so that ICW and ECW are both determined. MF-BIA like SF-BIA also uses regression models to evaluate FFM, TBW, ICW and ECW.

ViScan is a tetrapolar impedance method. The abdominal body composition values total abdominal adiposity and visceral fat are derived from extrapolation of impedance measures at 6.

It consists of a wireless measurement belt and an infrared beam projected over the waist at the umbilical sagittal plane. It detects the waist circumference using two infrared sensors on either side of the base unit. BIS uses a series of frequencies and it is based on the Cole—Cole plot and Hanai models which characterise the measurement segment with parallel circuits for ECW and ICW, and accounts for a capacitive effect introduced by the non-conducting membrane that separates the ICW and ECW.

BIS firstly determines the electrical resistance of ECW and ICW, and then calculates the volumes of these respective components. By differentiating between extracellular water and intracellular water spaces, BIS can provide an estimate of body cell mass.

The multi-segmental approach which is based on 8 contact electrodes 2 on each hand and foot assumes that the body is made up of a group of cylinders left and right arms, the left and right legs, and the total body are measured and provides body composition values for the trunk and limbs as well as the whole body.

Multi-segmental BIA SEG-BIA is available in both single-frequency and multi-frequency body composition monitors. Figure 1 Electrodes placement on hand and foot.

Source: MRC Epidemiology Unit. Figure 3 BIA using the hand to foot 8-electrode body composition monitor. Figure 4 Estimating abdominal fat using ViScan. A selection of published BIA equations for predicting FFM, FM, TBW, and ECW, which include description of BIA instruments, the criterion used to validate the equations and standard error of the estimates was published by Kyle et al.

When deriving fat mass from those equations, the absolute error of estimates at individual level will vary, but the ranking of individuals i. relative validity will be relatively stable regardless of the equation used.

If, in the analysis, the investigators are only interested in determining ranking of body composition traits rather than absolute values, an alternative approach, which avoids the need for population specific validation equations can be used, as described by Vanltalie et al , Tyrrell et al.

This method involves correcting lean and fat masses kg for height cm by deriving the following indices. Total body water then requires adjustment for the hydration of lean tissue H LT to calculate lean mass.

The adjustment for H LT assumes a constant level of hydration between individuals. Based on this theoretical approach, individuals of the same sex can be ranked according to this simple BIA index. Considerations relating to the use of BIA in specific populations are described in Table 3.

Estimates of body composition values are dependent on the validity of the BIA equation used for the population.

Refer to section: Practical considerations for objective anthropometry. About About the DAPA Measurement Toolkit What's New Other resources Toolkit Team Contact. Introduction Validity Reliability Error and bias Feasibility Data processing Statistical assessment of reliability and validity Harmonisation.

Introduction Subjective methods Objective methods Harmonisation Videos Dietary assessment decision matrix. Introduction Subjective methods Objective methods Harmonisation Videos Physical activity assessment decision matrix. Introduction Subjective methods Objective methods Anthropometric indices Harmonisation Videos Anthropometry decision matrix.

Anthropometry Domain. Bioelectric impedance analysis. What is assessed? How is the measurement conducted? When is this method used? How are estimates of body composition derived? Populations Further considerations Resources required Instrument library References.

Impedance comprises both resistance and reactance: The resistance R reflects the opposition of the tissue to the flow of electrons. It is related to the amount of water present in tissues. The reactance Xc by contrast reflects the capacitive losses caused by cell membranes.

Single-frequency BIA SF-BIA SF-BIA frequency of 50 kHz also known as tetrapolar impedance is the most commonly used BIA instrument, based on 4 contact electrodes 2 injecting and 2 sensing electrodes.

Multi-frequency BIA MF-BIA MF-BIA frequencies up to kHz allows differentiation of intracellular and extracellular components of total body water.

Bioelectrical impedance spectroscopy BIS BIS uses a series of frequencies and it is based on the Cole—Cole plot and Hanai models which characterise the measurement segment with parallel circuits for ECW and ICW, and accounts for a capacitive effect introduced by the non-conducting membrane that separates the ICW and ECW.

Multi-segmental approach The multi-segmental approach which is based on 8 contact electrodes 2 on each hand and foot assumes that the body is made up of a group of cylinders left and right arms, the left and right legs, and the total body are measured and provides body composition values for the trunk and limbs as well as the whole body.

Manufacturers guidelines provide calibration values cut offs. BIA can be performed standing or supine, via hand to foot or arm-leg or foot to foot or leg-leg impedance depending on device.

Hand to foot measurements has been shown to be more accurate than foot to foot measurements. However, foot to foot impedance instruments are more user friendly for those working in the field. Height, weight, gender and physical activity level are typically required by the BIA instruments which then measure the resistance in the majority of BIA devices and reactance for multi-frequency BIA only.

For the ViScan, the participant is supine and the wireless measurement belt is placed directly on the skin at the umbilicus in the sagittal plane.

Participant instructions Reliable BIA requires protocol standardisation and control from the following: Refraining from consuming caffeine tea, coffee and energy drinks and alcohol the day before the test 24 hour prior the test Avoiding vigorous activity 8 hours before testing No eating or drinking within 4 hours of the test No diuretics within 7 days of the test No measurements to be carried out if participant has electrical device such as pacemaker or cochlear implant Shoes, socks, tights to be removed Hands and legs slightly separated from the body If skin is moist or covered with body lotion, clean the area with alcohol wipes.

BIA is a reasonable method to assess and track body composition at population level but not sufficiently accurate to monitor change within an individual due to the error within the measurement. BIA is widely used in clinical medicine, sports medicine and weight reduction programmes.

BIA monitors report a value of resistance R expressed in Ohms Ω. If a multi-frequency device is used, a value of reactance Xc , expressed in Ohms Ω , is also provided. R, or the combination of both R and Xc, are then used in regression equations to estimate body composition together with other population characteristics such as height, weight, gender and activity levels.

Most BIA instruments use in-built manufacturer prediction equations to estimate body composition variables; BIA equations generated by manufacturers are of commercial value and typically not publically available.

The equations are generic and may not be applicable to specific populations. Typically instruments equations are not to be used in children under 7 years of age and in older individuals over 65 years of age. Numerous prediction equations of varying complexity have been published to derive body composition from BIA.

Ideally in a BIA study, it is recommended to develop prediction equations and cross-validate these models against a criterion e. However, this is not always feasible due to cost and technical constraints; therefore body composition values should be generated from published prediction equations which closely match the study population.

When selecting a BIA prediction equation, ensure they are suitable for the device used foot to foot vs hand to foot and population. Consider the use of multiple BIA equations and then generate the average, which may help control the bias and variation inherent in the measurements. BIA equations A selection of published BIA equations for predicting FFM, FM, TBW, and ECW, which include description of BIA instruments, the criterion used to validate the equations and standard error of the estimates was published by Kyle et al.

Further information in Wells et al. An overview of the characteristics of BIA is outlined in Table 2. Strengths Non-invasive.

Safe to use not recommended for participants with a pacemaker. Can be measured without difficulty in almost any settings. Limited burden to participant. Limited burden to researcher in terms of collection and analysis.

Requires no input by participant and as such no risk of respondent biases. Quick and easy to administer. Easy to use.

It can be portable. Relatively inexpensive. Minimal participant participation required. Quantum VII See details. Quantum V Segmental BIA. Quantum VII - Bioelectrical Impedance Analyzer BIA.

Quantum IV - Body Composition Analyzer. Quantum Legacy. Lemo 5-pin Subject Cables. Power supply. View all.

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