Anna Evans

BMI – Pros and Cons, What It Shows, And How It Is Calculated

Let's break down the pros and cons of BMI and how it is calculated.


Throughout history, excessive weight has been a major concern, and different cultures have held varying degrees of value placed on it. Interestingly enough, it’s still a hot topic in today’s society, and the BMI method has been fueling this discussion for many years.

You have probably heard of BMI – maybe you’ve seen it on your doctor’s chart, or maybe you’ve been trying to calculate yours on your own. Body Mass Index (BMI) is a number that tells us how healthy a person is based on height and weight. This measurement is used globally to check if the person has excessive weight or obesity.

But what does that number really mean? Let’s break down the pros and cons of BMI and how it is calculated.

What does BMI mean?

BMI stands for body mass index, and it is a calculation based on your height and weight. It doesn’t actually measure the amount of fat in your body – instead, it just estimates how much of your body mass comes from fat.

BMI guidelines chart

If your BMI is below 18.5 then you are thought to be underweight; 18.5–24.9 is a normal indicator; 25–29.9 – overweight; 30–39.9 – obese; 40+ is considered morbidly obese/severely obese.

Knowing where you fall in this range can help doctors make decisions about treatments or medications that may be right for you.

How is your BMI calculated?

To calculate your own BMI all you need to know are your height in meters and weight in kilograms. The formula looks like this:

BMI = Weight / Height²

For example, if someone weighs 60 kg (132 lbs) and measures 1.65 m (5’5) tall then their calculation would look like this: 60 / 2.7225 = 22 which falls into the healthy category.

Find out your body mass index right now, by using Healthypedia’s BMI calculator:

BMI Calculator

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Body Mass Index – Its pros and what it shows

There are several reasons why BMI is such a popular tool among medical professionals.

1Shows the mortality risks

Knowing something as simple as BMI is one way you can help reduce your risk of all-cause premature death as studies have proven the connection between the measurement and mortality risks.

One of those is a large 2016 research that involved data from over 10 million people across 32 countries for an average of 14 years. After accounting for factors like smoking and preexisting conditions, the researchers selected 4 million adults to analyze by BMI.

The study revealed that people with a BMI in the range of 22.5 to 25 kg/m2 had a lower mortality risk compared to those who were overweight or underweight. Each 5-unit increase above 25 kg/m2 was associated with about 31% higher chance of premature death, whereas being significantly overweight (BMI between 35 and 60) increased the risk nearly threefold.

2Shows risks of cardiovascular diseases

BMI, or body mass index, has been used for some time to help assess one’s risk of developing cardiovascular disease. Many studies show that BMI results that fall into the ‘obese’ category are associated with shorter longevity and a significantly increased risk of cardiovascular mortality compared with normal BMI.

Despite similar longevity compared with normal BMI, being overweight was associated with a significantly increased risk of developing CVD at an earlier age.

One of the large studies that involved over 190 thousand people showed that a higher BMI increases the risks of all kinds of cardiovascular diseases.

BMI and Cardiovascular Disease Incidence, stats Source: JAMA Network

3Shows risks of cancer

Being overweight or having obesity is linked with a higher risk of getting 13 types of cancer. There is no surprise that a higher BMI, which is used to determine obesity, is associated with higher risks of developing cancer.

According to research from the American Cancer Society, excess body weight is thought to be responsible for about 11% of cancers in women and about 5% of cancers in men in the United States, as well as about 7% of all cancer deaths.

4Shows risks of type 2 diabetes

One of the largest studies of the UK population, which included data from more than 445 thousand people, showed that BMI is a better predictor of risk for diabetes than genetic predisposition.

People in the highest BMI group (average 34.5) had an 11-fold increased risk of diabetes compared to participants in the lowest BMI group (average 21.7).

The highest BMI group had a greater likelihood of developing diabetes than all other BMI groups, regardless of genetic risk.

5Shows risks of hypertension

Studies have found a strong correlation between an elevated body mass index (BMI) and hypertension. Those who have higher BMI measurements are more likely to suffer from high blood pressure, making this association a serious concern for health experts.

6It’s easy to calculate

BMI is relatively easy to calculate and does not require any special equipment or tests. You only need a weight scale and a way to measure your height. Not everyone has those, but it’s still pretty affordable for many.

7Shows the dynamic between regions and populations

Understanding the BMI of a population can be a valuable tool in monitoring the general health of a country. Generally, body mass index is studied over the long term and has been shown to demonstrate potential trends in nations throughout the world. Examining BMI gives us an indication of how countries are growing and developing, as well as provides insight into healthcare standards and opportunities available to citizens.

It also helps us compare similar nations to each other to better understand their respective health outcomes. This ability to track health status at a population level offers many potential insights and can potentially affect public policy decisions.

Body Mass Index – Cons and limitations

BMI can be an effective way to assess someone’s overall health, but it also has its limitations.

Doesn’t distinguish between fat and muscles

For example, people who are very muscular may have a high BMI but still, be healthy because they don’t have a lot of fat on their bodies. Similarly, people who appear to be thin may still have a high percentage of body fat and therefore be at risk for health issues related to obesity.

Doesn’t take into account lifestyle

Another limitation of BMI is that it doesn’t take into account other factors like diet and exercise habits that contribute to overall health and well-being. In other words, just because someone has a ‘normal’ BMI doesn’t necessarily mean that they are healthy – they could still have unhealthy eating habits or lack physical activity which could put them at risk for various illnesses and diseases.

Doesn’t show dynamic

This issue directly follows the previous two: body mass index can’t show you a proper dynamic of how your body changes. No matter if that’s a positive or negative change.

Imagine that your height is 180 cm and your weight is 105 kg. In this case, your BMI is 32.4 and you’re considered obese. After hearing this news, you’re improving your lifestyle, starting to run every day and feel healthier, but after a couple of months, your bathroom scale shows 104 and you’re still considered obese with a BMI of 32.1. You would probably feel a little bit discouraged! What this doesn’t show, is that you’ve probably lost a few pounds of fat, but gained some muscles, which is a big improvement!

Another example is the body mass index of elderly people, who are known to lose muscle mass and gain fat instead. If their BMI was healthy before, they would be still considered healthy, even if their body is undergoing unhealthy processes.

Doesn’t vary for different biological sexes

When relying solely on BMI to determine if a person is healthy or not, one of the most important factors that can be overlooked is biological sex difference. This happens because the BMI method was created during a time when the differences between male and female bodies weren’t as examined.


Let’s sum BMI up

Calculating your BMI can give you some insight into how healthy you are based on your height/weight ratio. If your result falls into categories besides normal, it can be a signal of different health issues, including high risks of cardiovascular disease, diabetes, hypertension, and other serious illnesses. It’s important to remember though that while numbers do tell part of the story – they don’t tell everything. Body mass index has some serious limitations, and it’s not supposed to be used as the only tool in determining the state of your body.

Hungry for knowledge? Here’s more

A professional nutritionist Richie Kirwan from the Myprotein YouTube channel explains how BMI works and what are the downsides of this method.

Healthypedia FAQ

BMI, or Body Mass Index, is a number to determine how healthy a person is based on height and weight. This measurement is used globally to check if the person has excessive weight or obesity.

To find our your body mass index you need to divide your weight in kilograms by height in meters squared.

The Healthy range for body mass index is anything between 18.5 and 24.9.

To find out your body mass index in pounds, you should use the following formula: weight (lb) / [height (in)]2 x 703.

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