Beyond BMI: Bioelectrical impedance analysis

Charlotte Edwards 27 February 2019 (Last Updated February 27th, 2019 12:22)

Body composition monitoring is a familiar concept to anyone who has ever had their BMI tested. In such scenarios, BMI testing will give a reasonably accurate sense of weight and health but not much more. Now scientists are working to conduct body composition monitoring in far greater detail in the hope that much more comprehensive information could lead to new treatments, as specialists from Tanita explain.

Beyond BMI: Bioelectrical impedance analysis
Japan-based company Tanita specialises in precision electronic scales and has almost 50% of the domestic market share. Credit: Tanita.

Bio-electrical Impedance Analysis (BIA) is a method used to monitor health by looking at body composition. It measures body fat in relation to lean body mass and is said to be more accurate than BMI testing. A normal balance of body fat and muscle is associated with good health and longevity so BIA tests can aid clinicians in helping their patients change their diet and lifestyles accordingly.

Japan-based company Tanita specialises in precision electronic scales and has almost 50% of the domestic market share. All Tanita body composition monitors are said to use advanced BIA technology. Tanita international commercial manager Simon Bradeley explains more about the benefits of bioelectrical impedance analysis (BIA) and Tanita’s latest tech.

Charlotte Edwards: Can you explain the purpose of BMI testing and its benefits?

Simon Bradeley: BMI testing is really for large population studies. It’s really good for testing large groups of people and getting some average numbers. It’s a very general measure which is just looking at weight in relation to your height but it has its limitations when you start to look at individuals.

CE: In what ways is body composition monitoring a better alternative to BMI?

SB: Essentially because it looks at you personally as an individual. So, it will look at your muscle mass and body fat separately whereas BMI doesn’t, it just looks at your weight. The classic example is if you get a rugby player who is very muscular and you put them through BMI it might say that they’re morbidly or clinically obese but actually when you look at their composition and you measure their muscle mass and body fat, you can see that their risk factors, especially associated with body fat, are very low because they have very low body fat levels and visceral fat levels. They’re just got good muscle mass levels. So it’s about looking at the individual specifically, rather than putting them through this very loose general guide that’s based on weight rather than composition.

CE: Can you talk me through some of Tanita’s body composition monitors and how they work?

SB: We are basically the innovators of the BIA technology. So we are a Japanese company that stemmed out of our business in Japan. We utilise this BIA technology to send very low electrical signals through your body. Our bathroom scales for home use or our professional devices that you can find in hospitals, fitness clubs and spas around the world, send bioelectrical impedance analysis throughout the body which then calculates the reactance and the resistance of different cells and different substances within the body to then very accurately calculate how much muscle you’ve got, how much water you’ve got, how much body fat you’ve got, the quality of that muscle. Then we take that data and work out metabolic rate compared to age.

So you stand on the scale, the scale takes your weight and then little electrodes on the foot points send little electrical signals through your body. You don’t feel anything, it’s very low, very safe and within ten seconds on some of our scales you could have up to 45 different readings. I guess there are nine readings that people focus on and you can have that on your mobile phone instantly.

CE: So there is no medical training required to use the devices?

SB: To use our home use devices, no. Most of our output and data is colour coded. We try and make it really simple to understand. There is some data in there that clinicians will use and could be used in oncology departments or others, so there is some data that is more difficult to understand. Your body fat, for example, the device might say that you’re at 15% body fat but it will also give you a green, amber or red. Red is not good, green is good and orange is borderline.

I guess with metabolic age as well, we might talk about body fat or intracellular mass which the clinicians will understand but it’s the simple metabolic age that hits home most of the time.

CE: How many hospitals and professional environments use your equipment?

SB: It’s difficult to put an exact figure on it because we tend to work in many different departments. Some hospitals will and four or five devices and some hospitals won’t have any but I would say 90% of hospitals across the UK would have some form of BIA devices. We are the market leaders so you could argue that most of them probably are Tanita.

CE: What new treatments could this more accurate alternative to BMI lead to?

SB: Most dieticians working in a clinical office will look at body composition and not BMI because it’s much more personal. On a general level BMI is fine, the minute you walk into a hospital, I’d say 90% if not 100% of dieticians will be using body composition monitoring and not BMI. It’s much more accurate and it means any treatment is much more personal. Tanita were the first organisation to release muscle centile charts for children, which is a big thing for the industry.

If you use BMI with children, it’s not a great indicator or specific. A lot of child obesity specialists will use body composition because it’s much more positive. With body composition, instead of talking about body fat or weight, which can have a lot of negative connotations, you can talk about muscle and hydration and have a much more positive conversation.

One of the benefits with BIA with children is that a child with low muscle mass is potentially at greater risk of disease in later life than a child with high body fat and you wouldn’t know that from BMI.

CE: So what’s next for Tanita?

SB: We just recently released a new device, the MC-980 Plus, and that’s got some new technologies in that we’ve added to another product called the 780. So those two devices are our bestselling clinical devices. A sarcopenic indicator has been added which can give you the risk of disease and mobility rates in later life and we’ve also added much more accurate reading technology.