What’s all this ongoing controversy that the Body Mass Index, a ‘measure of a person’s fitness’, is not accurate as per physiology? I explore the topic in brief here.
Here in this blog, I’ve listed several ways in which you can determine your fitness, just by looking at your body shape, and doing a little Maths. It’s actually very simple. And we also have details of the controversy behind methods of measurement explained.
Before we proceed any further, it is important to first get an overview of what exactly is BMI (Body Mass Index).
Body Mass Index
Your weight or height taken separately, is not a factor good enough to determine your fitness. You need to compare both your height and weight to know your fitness. And that’s exactly what is done by BMI.
This formula is used for calculating your Body Mass Index. Your weight in kilograms needs to be divided by your height in metres squared. That will give you an estimate of your BMI.
weight = 65 kg,
height = 1.7 m,
BMI = 60 kg / (1.7)2 m
That was mine. What about yours?
Note that you cannot change the units. If you change the units, you will get erroneous results.
If you think you don’t know your height and weight in SI units, go to Google and do the conversion: only then will you get a proper result.
Then: how will you convert this data into information? You’ve successfully calculated your BMI, how will you decode that to determine your fitness? Here’s a table to help you in that.
Compare your BMI to the above table, and check the category you fall into as per your BMI. As per convention, a person’s BMI should normally be within the range 18.5 to 25.This indicates that you are not overweight.
The main use of BMI is to determine your body’s weight in reference to your height.There is a certain ‘percentage’ of your height that the weight of your body should not cross, for you to be a healthy person.
BMI is therefore, not a measure of your body fitness. It is a measure of your healthiness based on your weight in comparison to your height.
Disparities in BMI
It is known that an infant or a child does not have the proper weight to height ratio. And they vary from generation to generation. Fitness is something that is very difficult to calculate in children upto 10 years of age. In such a case, BMI is not used.
In such a case, the percentile of the baby’s weight in comparison to other babies of his/her age is calculated. This is a better measure to estimate for the child’s fitness.
If the percentile is <5%, it means that the child is underweight, and if >95%, it means he/she is overweight.
So the next time, don’t just measure your child’s weight, calculate his/her BMI, and be aghast. BMI is not an accurate measure before the age of 10.
BMI Leads to Height-to-waist ratio
Recent studies have proven that BMI can be inaccurate for certain groups of people, especially South Asians. South Asians tend to have a shorter height in comparison to their weight. The research has a considerable base to lay a foundation on.
As I said before, and also illustrated with the maths, BMI is effectively a measure of your body weight in comparison to your height.
To begin with, BMI does not account for the inequal fat distribution in the body, or either muscle mass. Excess fat in different parts of the body can have widely-varying effects on your health.
For example, people with more muscle mass are actually fit, but when you calculate their BMI, the measurement inadvertently takes into account the muscle mass as fat! There you go: you have a problem!
And fat can also be good. Fat stored in certain parts of can actually be good for decreasing mortality rate.So, after all this concrete evidence, would it still be good to use that outdated BMI, which is about 160 years old?
The Biggest Flaw of BMI: What the Hell is Muscle?
BMI makes no distinction between muscle mass and fat, therefore returning erroneous results.
We know that muscles weigh more than fat. Therefore, muscle mass is a huge contributing factor to body weight.
At the climax of his career, he weighed 142 kg, and was 6 feet 2 inches in height (1.8 metres). If we calculate his BMI, we get it as 32.4. From the table given above, we conclude he would fall into Moderately Obese (Class I)!
Does he look or feel like obese, being a well-known famous wrestler? Absolutely not. If we attempt to explain his erroneous result, we deduce that it is due to the fact that he has more muscle mass than an average person.
So, at the end of the day, even if you’re not obese, BMI may term you to be so, if you have more muscle mass. Is that fair, or rather, correct? Medically speaking, you’re not obese.
Despite being experimentally and scientifically proved to be misleading, almost all authorities still refer to BMI as the standard. Do we need to change this? Obviously yes, and also no. I’ll explain why a bit later. Before that, let’s learn about the replacement for it.
Waist Size: A better indicator?
Researchers from Medical Research Council Epidemiology Unit, UK have recently found a connection between Type II diabetes and waist size of a person.
And there’s proof for this: Americans carry more fat around their middle sections than the British, and this perfectly accounted for the larger number of Type II Diabetes cases in the USA than in the UK.
The reason for this is the probability of a person dying earlier is based on fat distribution in the body. The most common disease that occurs due to excess fat is Type II Diabetes. At the end of the day, fitness is governed by the amount of extra fat that a person carries in his/her body.
Since we’ve found a direct relationship between diabetes and waist size, it would be safe to use waist size as a perfect indicator of one’s fitness. Fitness over here refers to the lesser probability of a person dying before his/her natural age of death due to cardiovascular diseases. If you define fitness like this, then height-to-waist ratio is the clear winner.
Abdominal Fat: The ‘red signal’
There is one single principle behind all this: abdominal fat affects vital body organs such as the liver, kidney and heart more severely than fat in any other part of the body. And measuring the size of your waist gives a relative estimate of your abdominal fat.
You are to measure the circumference of your waist, not your hips. That’s a very common mistake that is made.
Your waist is approximately an inch above your belly button, at the centre of a pair of muscles known as the external obliques.
Calculating WtHR is exceedingly simple. The tape should be positioned in a horizontal straight line, 1 inch above the belly button. This position is crucial for a proper measurement. You also need to know your height.
WtHR = Circumference of Waist (inches) / Height (inches)
A measurement taken in inches is preferable. This is because the circumference of your waist is preferably measured in inches.
You need to convert your height into inches too. Remember, 1 foot = 12 inches, and then do the conversion. I’m giving an example below.
Height = 6 ft. 8 in. = 80 in.,
Circumference of Waist = 28 in.,
WtHR = 28 in. / 80 in. = 0.35
There’s a convention here too. Your WtHR should be equal to or less than 0.5.Then you can be confident of being quite fit.
If you still want more precision, here’s another table from Wikipedia that illustrates how to decode your WtHR.
There is no such lower limit for WtHR. However, female and male should preferentially not go to a WtHR lower than 0.42.
Anything above 0.5 indicates a potential risk. If WtHR is more than 0.57, the person is considered to be obese; and a WtHR of 0.58 or above is imminent danger.
WtHR is good, but BMI is better
For those saying I’m making an ironical statement, I advise you to take this statement with a pinch of salt. We have brushed off BMI as not accurate, but it actually is more accurate than WtHR when it comes to determining overall body fitness.
There are other better ways of measuring BMI rather than that stupid equation of household measurement of BMI. For that, you need to go to a fitness clinic.
However, that is not always possible. Therefore, for quick and household use, WtHR is a better option.
Body Shape: A quick glance to test
Getting a good body shape is also important. Experts say that the hourglass body shape is the perfect choice, and is the one that is most healthy. The cone-shaped is also a healthy body shape.
Contrary to popular belief that body shapes are all about looks, looking sexy, and what to wear, they have a significant contribution to your health.
There are health implications of each type of body shape. An hourglass shaped body would give you the best WtHR. As an added benefit, those who have an hourglass-shaped body have a lesser chance of falling prey to more abdominal fat in future.
A cone-shaped body is more or less the same. A person with a cone-shaped body always has a low WtHR, he/she has to. Healthy male bodies are normally cone-shaped, and females can have both.
A pear-shaped body and a diamond-shaped body has clearly distinct abdominal fat. If you have this kind of body shape, don’t be worried. There are two interpretations: more abdominal fat, or less muscle mass. If you have a high WtHR, and this kind of body shape, you need a cause to care of.