The BMI formula | Understanding BMI 10 ways

The BMI Formula is what you use to calculate your BMI. A BMI calculator assesses your body mass index and is a broad indication of whether you are at a healthy weight or not. Put simply, if your BMI is too low, you are underweight, and if it’s too high, you are overweight, obese or “morbidly obese” which puts you at risk for many health complaints, even an early death.

BMI is not that difficult to understand. The BMI formula can be easily explained by delving into the 10 questions below.

#1: What is BMI?

BMI stands for Body Mass Index. It’s a measurement of your body density and can be (generally) used to measure if a person is too heavy or too light for their height – meaning that they may be at a health risk. Use the BMI formula to calculate your best weight, or best weight range.

#2: What does BMI measure?

The BMI formula measures your weight (body mass) divided by the square of your body’s height. Traditionally, this was measured in units of kilograms/meters squared (kg/m2) but there are many imperial conversion methods available.

BMI formula

#3: When was the BMI formula developed?

Between the years 1830 and 1850, Adolphe Quetelet developed the BMI formula as part of a study into what he called “social physics”. However, it didn’t really take off until the 1970s, according to Wikipedia.

Its popularity was traced back to “a paper published in the July 1972 edition of the Journal of Chronic Diseases by Ancel Keys. This found the BMI to be the best proxy for body fat percentage among ratios of human body weight and height.”

#4: How do I work out my BMI?

To use the BMI formula, take your weight in kilograms and divide it by your height in centimetres squared. I usually do this “old skool” – I grab my calculator and a pen and work it out myself. If you prefer imperial (strange fool you are) then take your weight (mass) in pounds and divide this figure by your height in inches squared.

Prefer to use a calculator online. Here is a Metric BMI Calculator and an Imperial BMI Calculator.

#5: Who should not use BMI to track their weight?

There are many people for whom the BMI formula (and therefore the BMI calculator) is an ineffective method of measurement. If you are pregnant, an athlete, a child, of Asian descent or a bodybuilder with low body fat but high mass – then you may get an inaccurate reading. Check out my post The BMI index is not suitable for everyone. Here’s why for more info.

BMI formula

#6: Will having a “normal” BMI ensure that I am slim?

No, not necessarily. The way your body looks is influenced by many factors – your age, your fat distribution, your skin tone and your mass distribution. There are some people who have a “high” BMI who appear “normal” and some people who have a “normal” BMI who appear too fat or too thin. Check out this link Illustrated BMI Categories and check out the amazing body variations you can see.

#7: What BMI is the most attractive for men and women?

A while ago, I did a blog post on the subject of Most Attractive BMI and found some very skewed results. According to Wikipedia, for example, in Hong Kong, you are considered “overweight” once your BMI crosses 23 – where I live in Australia, the figure is 24.9 (or even 25 for some websites). Here in Australia, the BMI formula is used slightly differently. We tend to think someone is “underweight” when they hit >20 – but in many Asian countries the figure is >18.5 or even 17.5 – this provides huge variances.

#8: What to do if your BMI is too high

Although many health experts suggest that BMI is not a great way to measure your health, I beg to differ. Keep your weight as low as you can – most of us will never be in any real danger of being “underweight” – so just aim for low. If your BMI is too high – you need to reduce the amount of food you are eating. In my opinion (and I am not a health professional) portion control is the only way to go to manage your weight. Forget detoxes, forget diets, forget fasting, forget exercise. Limit your portions. That’s all you really need to do.

BMI formula

#9: What to do if your BMI is too low

If your BMI is too low, you need to try to bring it up. Include more healthy fats in your diet and increase your portion sizes. Visit a nutritionist and begin a healthy weight gain plan. Check out this Managing a Low BMI article on Livestrong which says, “The Academy of Nutrition and Dietetics has some healthy ways to add extra calories to your diet.” Use the BMI formula to get to where you want to go.

#10: What’s next for BMI?

There’s a new measurement in town, kids – but I won’t be using it because I’m unlikely to get good results! The new measurement is called the ABSI – or “A Body Shape Index”. This measures body shape through waist circumference, adjusted for height and weight.

According to the Daily Mail, “Scientists developed this measurement after finding that it was difficult to determine waist circumference through Body Mass Index measurements. The scientists, from City College of New York, looked at a sample of 14,105 adults and found that higher death rates were found for both high and low values of BMI and waist circumference.”

Apparently this is more accurate for measuring if you’re likely to suffer an early death.

A final word on BMI

You are a lovely, gorgeous human being – “You’re a vision! Don’t change a single thing!” However, if you are feeling a little blobby and overweight – that’s not living your best life. Get your BMI under control – take your time – and reap the rewards of having a healthy, vibrant body.

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