BMI, or Body Mass Index, is an indicator that measures and categorizes people into different groups based on their ratio of height and weight. The formula of BMI is very simple: You just need to divide your weight by your height square to get the result. It is a popular index used worldwide to categorize people based on their height and weight ratio and determine whether they are at risk of chronic diseases.
Body Mass Index (BMI) = Weight/Height²
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The History of BMI
The index was not initially named BMI until 1972. It was created in 1830 by a Belgium mathematician, astronomer, statistician, and sociologist named Lambert Adolphe Jacques Quetelet. Back then, it was known as the Quetelet Index.
Later, In 1972, American Physiologist Ancel Keys named the index BMI or Body Mass Index. From that point on, we have known the measurement as BMI. The index was invented for having a rough guess over a population and was not meant for individual categorization. Back then, Ancel Keys mentioned that even measuring population has its limitations and does not bring the full picture.
Still, the index became popular due to its ease of calculation. Anyone can calculate it anywhere with ease, and thus, it has become a global health measuring benchmark for a very long time.
Criteria of BMI
Based on the formula result, BMI is mainly divided into 4 criteria. Those criteria are:
- <18.5 (Below 18.5) is considered as underweight
- 5 – 24.9 is considered as the normal range
- 0 – 29.9 is considered overweight
- 0 + is considered obese
Even among obese, some categories showcase what type of obese someone falls into. It has 3 types.
Why BMI Is Not a Good Measure?
There is a fundamental problem with BMI. It does not consider a person’s lean or fat body mass.
How can you measure whether a person is healthy or obese if you do not know the body fat percentage of a person?
My height is 5 Feet 10 Inches (177.8 CM), and I weigh 86 KG.
My BMI = 86/177.8² = 27.2 kg/m²
I fall into the overweight category. My body fat percentage is around 15% to 17%, which is considered the healthy range.
The result can be very misleading as BMI does not consider fat percentage. People of similar height and weight can score the same in BMI but can have very different body compositions. One person with a good amount of muscle may be shown as overweight or obese by Body Mass Index, but the reality can be far from the truth.
MY BMI
Still don’t believe me?
If you are somewhat familiar with bodybuilding, then you know Chris Bumstead (CBUM), who has been Mr. Olympia Champion five times in a row (as of now). When CBUM is in contest mode, he usually weighs around 104 KG. Chris Bumstead’s height is 6 feet 1 inch (185 CM).
CBUM’s BMI = 104/185² = 30.4
It shows CBUM as obese when, in contest time, CBUM remains in the 4% to 5% body fat range. This shows how inaccurate BMI can be.
What Research Has to Say About BMI?
There has been much research measuring the accuracy of BMI. Let’s see what some popular research concludes about BMI.
- In 2001, the Journal of Nutrition conducted research to determine the accuracy of BMI. For this experiment, they chose subjects with around 30 BMI. They found that people with less than 30 BMI were not fit. For clarification, they measured their body fat percentage and found that they actually should fall into the obese category. So, the accuracy of BMI is very suboptimal.
- Another study conducted on people of different ethnicities found that people of different ethnicities have different body compositions, and BMI is almost always inaccurate when trying to measure their health.
- The American Medical Association conducted a study in 2005 to find out which BMI range people are more likely to get sick. The study mainly involved Japanese and Mongolian people. Even though Mongolian people had higher BMIs than Japanese people, they were less sick than the Japanese.
- Also, to find out the death rate of different BMI categories, it was found that people who fall under the underweight category had a higher death rate than the obese category. So, if you are slim, it does not mean you are fine. You might be skinny and fat.
What Problem Inaccuracy of BMI is Causing?
As we explained throughout the article, BMI is not an accurate measurement of fitness. There are many indicators that are not accurate, but then why is BMI taking all the blame?
The reason behind this is the mass popularity of BMI. As the index is very easy to use, it became popularized, so people and even organizations started using it as a benchmark. Problems that BMI created:
- Many insurance companies deny claims and do not want to provide insurance if you do not meet certain BMI criteria.
- In jobs where fitness level is a crucial factor, like the military, your selection might be hampered because you do not meet certain BMI Criteria.
- It can be a reason for demotivation, especially for beginners, as it can give them false results that may hamper their motivation.
That is why the measurements that consider body fat percentage in their calculation are more reliable than BMI. We have a detailed article related to that “Fat loss Vs Weight Loss.”