What if I told you that with a simple tool you could measure your body composition in a matter of seconds? Bioimpedance body composition analyzers (BIA) promise this and more. But how much trust should we put in these devices? How do they compare favorably to the gold standard, Dual-Energy X-ray Absorptiometry?

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The Lure of the BIA

Bioimpedance body composition analyzers come in various forms: home scales, handheld devices, and even fancy InBody scanners. All these promise quick results, with body fat percentages, muscle mass, and even basal metabolic rates at our fingertips. Another major advantage of BIA over Dual-Energy X-ray Absorptiometry (DXA) is the safety factor. BIA does not expose you to any form of radiation, unlike DXA, which uses low-dose X-rays. This safety aspect makes BIA a preferred choice for regular and repeated measurements, especially for those who wish to closely track their body composition changes over time.

What’s on the Market?

There is a vast array of affordable bioelectrical impedance analyzers on the market. However, they tend to exhibit rather low accuracy. When choosing such a device, it’s important to ensure that it comes equipped with hand electrodes and not only foot ones; this configuration tends to provide better sensitivity. Nevertheless, it’s usually better to undergo tests on professional analyzers such as those from InBody, TANITA, Charder, and BodyCompScale. These devices generally provide more reliable and detailed analyses, although they might be more expensive or require a visit to a healthcare or fitness facility.

InBody devices, especially the high-end models such as InBody 770 and 570, are known for their detailed reports and advanced features, including segmental lean mass analysis and intra-extracellular water balance. TANITA is popular for its range of products catering to different needs, including professional models and more affordable options for home use. Charder’s strength lies in its medical-grade products that are often used in hospitals and clinical research, providing highly reliable data. BodyCompScale, meanwhile, prides itself on its portable scales that are easy to use, making them popular in the fitness industry for tracking body composition changes over time.

Where to Take the Test?

To find a Bioelectrical Impedance Analysis (BIA) test near you, you can follow these steps:

  • Search Online: Use an internet search engine such as Google and search terms like “BIA test near me,” “body composition analysis near me,” or “InBody test near me“. This should yield results for nearby facilities that offer BIA testing.
  • Local Gyms and Fitness Centers: Many gyms, fitness centers, and health clubs offer BIA testing as part of their services. Contact your local establishments and inquire if they provide this service.
  • Medical Centers and Wellness Clinics: Some medical and wellness clinics may also offer BIA testing. This is especially true for clinics that specialize in nutrition, weight management, or wellness.
  • Nutritionists and Dieticians: Nutrition professionals often use BIA devices to monitor their client’s progress. It might be worth contacting a local nutritionist or dietician to see if they offer this service.

The test will cost you about 25…50 Euros/Dollars.

How Do BIAs Measure Up to DXA?

DXA has long been regarded as a highly accurate method for body composition measurement, albeit an expensive one, typically available only in clinical settings. But how do our BIAs fare when put head-to-head against DXA?

Studies have shown that BIA can overestimate body fat percentage, sometimes by substantial margins. The variability is primarily due to BIA’s reliance on hydration levels to measure body composition. If the body’s hydration level is altered, it can significantly affect the results.

For example, a male who is measured at 20% body fat by a BIA device might have a true body fat percentage of closer to 14% when measured by DXA. Similarly, women might experience an overestimation of up to 55%. This discrepancy is due to the difference in the way these devices measure body composition. BIA uses electrical signals, which can be affected by hydration levels, whereas DXA uses low-dose X-rays, which are much less influenced by these variables.

Factors Influencing BIA Accuracy

BIA estimates body composition based on how an electrical signal travels through your body. However, a variety of factors can affect the accuracy of BIA measurements. Here are some of the main factors:

  • Hydration Level: Hydration has a significant influence on BIA measurements, as water conducts electricity. If a person is dehydrated, the body’s resistance to the electrical signal may be higher, leading to an overestimation of body fat percentage. Conversely, if a person is overhydrated, it may underestimate body fat.
  • Food Intake: A full stomach can also affect BIA measurements. After eating, the increased amount of fluid and electrolytes in your body can lower the body’s resistance to the electrical signal, which could result in an underestimation of body fat.
  • Exercise: Exercise can alter hydration levels and blood flow, which can influence BIA measurements. It is generally recommended to avoid vigorous exercise for several hours before a BIA measurement.
  • Alcohol and Caffeine: Both alcohol and caffeine can influence your body’s hydration status, which could affect BIA results.
  • Skin Temperature: The temperature of the skin can affect the conductivity of the electrical signal, which could influence BIA measurements.

How to Prepare Yourself

To prepare for a BIA test and help ensure the most accurate results, follow these guidelines:

  • Hydration: Drink plenty of fluids over the 24-hour period preceding the test, but avoid drinking large amounts of water immediately before the test.
  • Food Intake: Avoid eating within 2-3 hours before the test.
  • Exercise: Avoid vigorous exercise for at least 12 hours before the test.
  • Alcohol and Caffeine: Avoid consuming alcohol or caffeine for at least 12 hours before the test.
  • Clothing: Wear lightweight clothing, and remove any metal objects, such as jewelry, as they can interfere with the electrical signal.

Results Sheet Interpretation

Here’s a brief explanation of some of the common terms you might see on a BIA results sheet, such as those provided by InBody devices:

  • Weight: This is your total body weight, including both fat and lean body mass.
  • Muscle Mass / Lean Body Mass (LBM): This represents the weight of your muscles, organs, and bones – essentially everything in your body that isn’t fat.
  • Body Fat Mass: This represents the total weight of fat in your body.
  • Body Fat Percentage: This is the proportion of your total body weight that is made up of fat. It’s calculated by dividing your Body Fat Mass by your total weight. Essential fat is the minimum amount necessary for survival. For men, it’s approximately 2-5%, and for women, it’s around 10-13%. Athletes usually have a body fat percentage of 6-13% for men and 14-20% for women. Fitness enthusiasts or those who are in good shape might have a body fat percentage of 14-17% for men and 21-24% for women. Average healthy body fat ranges are a bit higher: 18-24% for men and 25-31% for women. Overweight individuals typically exceed these ranges, with body fat percentages of 25% and higher for men, and 32% and higher for women.
  • Basal Metabolic Rate (BMR): This is the number of calories your body needs to maintain basic bodily functions, such as breathing and circulation, while at rest. BMR tends to be higher in men compared to women, due to a larger proportion of lean body mass. A rough estimate for an average male might be around 1600-1800 calories per day. For an average woman, BMR may range between 1400-1500 calories per day.
  • Total Body Water (TBW): This is the total amount of water in your body. Water plays a critical role in many bodily functions and is a part of every cell, tissue, and organ.
  • Segmental Lean Analysis: This breaks down the muscle mass in different regions of your body (e.g., right arm, left arm, trunk, right leg, left leg).
  • InBody Score: This is a single score that represents an overall assessment of your body composition. A higher score generally indicates a healthier body composition.
  • Phase Angle: This is a measure of cellular health and integrity. A higher phase angle is generally better, indicating stronger cell membranes and healthier cells.

Here is a detailed interpretation of InBody 770 test resutls: https://inbodyusa.com/general/770-result-sheet-interpretation/

Consistency of Results

The question on many people’s minds is: “Can BIA accurately track progress over time?” Unfortunately, the answer isn’t straightforward. Changes in BIA measurements over time could potentially reflect actual changes in body composition. However, due to the influence of external factors, it is hard to determine how much of the change is real and how much is due to these variables.

As one Reddit user aptly put it, you might be able to see trends with BIA devices, but the daily or weekly numbers can swing wildly. It’s like trying to find your way through a maze with a flickering torchlight – you might get the general direction, but the specifics can be a bit hazy.

What Is a Good Body Impedance Score?

Bioimpedance devices typically provide a range of scores which are categorized into brackets such as underweight, normal, overweight, and obese. These categorizations are based on the estimated body fat percentage derived from the impedance measurement. A “good” score, therefore, would generally fall within the normal range.

However, it’s important to note that these categories can vary between different populations, age groups, and sexes. For example, the acceptable body fat range for young adult males is typically lower than for females.

For devices like InBody, they provide an “InBody Score,” which is a comprehensive measure that takes into account muscle mass, body fat, and water balance. A score of 100 is considered perfect, but anything above 70 is typically seen as good.

Understanding Phase Angle

If you’ve spent some time exploring the results of your BIA test, you might have come across an intriguing term – ‘Phase Angle‘. This measurement, often abbreviated as ‘PhA’, isn’t as widely discussed as body fat percentage or lean muscle mass, but it holds significant value in health assessments.

So, what is Phase Angle? Without getting lost in the technical maze, Phase Angle is a calculated value derived from the relationship between the body’s resistance and reactance in a BIA test. In simpler terms, it’s an indication of body cell integrity and function, playing an insightful role in understanding a person’s nutritional status, muscular health, and overall vitality.

A higher Phase Angle is generally perceived as a positive sign. It suggests a large amount of intact cell membranes and lean body mass. On the contrary, a lower Phase Angle is associated with a reduced cell function, lower lean body mass, and potentially even malnutrition or disease.

For adults, the Phase Angle values usually fall between 5 and 7 degrees, with variances seen across different age groups, sexes, and health statuses. A score below 5 might indicate compromised health, while above 7 can be seen as a hallmark of robust health and cellular function.

As always, interpreting these values should be done in a broader context, taking into consideration a person’s overall health, lifestyle, and the specificities of the BIA device being used. Keep in mind that Phase Angle values are relative and should be analyzed over time to see if there are significant changes indicating improvements or decline in your health.

It’s worth noting that many professionals and individuals who’ve taken a deep dive into their BIA results consider Phase Angle as a valuable marker. It provides a unique perspective, separate from the more common body composition measurements, offering a broader picture of overall health and cellular vitality. So next time when you receive your BIA results, take a moment to look at your Phase Angle – it might tell you something that body fat and muscle mass numbers alone cannot.

My Personal Tale of Two InBodys

To add a dash of personal experience to this exploration, let me share my own interaction with two InBody devices – the InBody 570 and the InBody 770. As someone deeply interested in maintaining and improving my fitness levels, I’ve regularly been using both these devices to monitor my body composition.

Now, you might imagine that two devices from the same company would churn out almost identical results, right? Interestingly, that’s not the case. There’s a consistent divergence in the InBody Score given by these two devices, with a 3-5% difference generally noted. Intriguingly, the InBody 570 tends to give a higher InBody Score compared to the InBody 770.

That’s not all. The InBody 570 also appears to report a higher muscle mass and a lower percentage of body fat than the InBody 770. This disparity, while surprising, highlights the complexities and inherent variances even within the same brand’s different models of bioimpedance analyzers.

By the way, if you’re looking to cheat the results of an InBody test, a common trick is to hydrate excessively right before the test 🙂 This could potentially lead to an overestimated muscle mass and an underestimated body fat percentage due to the increased water levels in your body.

Body Fat (PBF) Test Results with Actual Photos (not mine)

Percent Body fat: 6.9% (see below, slide for photos):

InBody accuracy?

Percent body fat: 9.5% (woman):

Percent body fat: 34.5% (woman):

Percent body fat: 25.7%:

Percent body fat: 8.0%:

Percent body fat: 11%:


The information provided in this article is for general informational purposes only. The content presented on this website should be considered solely as opinions and personal experiences. Read more

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