Moving Well


BMI has long been used to indicate total body fat and weigh one’s health risks.

07 Jun 2021
Body Mass Index (BMI) measures a person’s weight in relation to their height to indicate total body fat. While it is not a direct measurement, the number does correlate with the amount. That means the higher the BMI score, the higher the person’s total body fat.

Your BMI score will determine which of four categories you fall under – underweight, normal, overweight, or obese – and anything between 18.5 and 24.9 is considered “Normal”. Doctors use BMI to assess one’s risks for conditions such as type 2 diabetes, heart disease, stroke, high blood pressure, sleep apnea, osteoarthritis, and certain cancers.

So how do you calculate BMI? It’s an easy formula: BMI = weight (kg) / height (m2) or in Imperial terms,
BMI = (weight (lbs) / height (in2)) x 703.

< 18.5Underweight
> 30Obese

There are also online calculators that let you calculate your BMI quickly and accurately.

That begs the next question: Is BMI an accurate measurement? Bear in mind that it only takes height and weight into consideration and ignores other factors that could determine someone’s health – age, sex, genetics, body fat, muscle mass or bone density, not to mention lifestyle habits such as amount and quality of sleep, and how active the person is.

For comparison, let’s look at the BMI of a 180cm-tall bodybuilder who goes to the gym every other day versus a 175cm-tall office worker with a relatively sedentary lifestyle. Both weigh 90kg. On the BMI index, they fall into the Overweight category. Yet the bodybuilder has a much higher lean muscle mass and far less body fat than the sedentary office worker. And that’s just the tip of the iceberg; when we start looking at more indicators of health, the two men’s profiles could not be more different. If we are to rely on BMI alone, the bodybuilder would be left wondering what he’s getting wrong whereas the sedentary guy might be under the false impression that he is not doing that bad but just needs to shift some weight. Neither scenario is helpful.

That said, it has to be noted that being overweight or obese puts one at greater risk for a variety of illnesses and even COVID-19. So of course it’s helpful to be aware of where you stand, health-wise but BMI can only serve as a starting point towards understanding the greater and far more complex picture that is the state of your health. For a more accurate assessment, try Boditrax, a state-of-the-art body composition tool that’s easy to use and intuitive. It reads 15 personal body composition measures in just 30 seconds and comes with a mobile app that lets you track your progress.