BMI (Body Mass Index) Chart: How To Calculate

What is body mass index (BMI)?

A term you may have come across in health check-ups or gym brochures is body mass index (BMI). This is relatively simple measurement used by healthcare providers to check the proportionality between your height and weight. The formula involves dividing your weight (in kilograms) by the square of your height (in meters).

For instance, if a man weighs 70 kg and his height is 1.75 m, his BMI would be calculated as follows:

BMI = 70 / (1.75^2) = 22.9

The resulting number provides an estimation of one's total body fat; the higher the figure, generally the greater the amount of body fat.

What is BMI used for?

Healthcare providers use BMI as a preliminary diagnosis tool. It facilitates identification of weight types and serves as a screening tool for certain health conditions.

Diagnosing weight types with BMI

BMI or Body Mass Index, is a numerical measurement derived from a person's height and weight. It is often used to classify people into different weight categories based on their BMI value.

Typically, healthcare practitioners classify different weight types based on the following BMI chart ranges (in kg/m2):

• Underweight: Less than 18.5
• Optimum range: 18.5 to 24.9
• Overweight: 25 to 29.9
• Class I obesity: 30 to 34.9
• Class II obesity: 35 to 39.9
• Class III obesity: More than 40

BMI provides healthcare professionals with a simple way to assess whether a person is underweight, normal weight, overweight or obese. This classification helps diagnose weight-related problems and determine potential health risks associated with weight status.

However, BMI or Body Mass Index is not the only tool used to identify weight types. Other methods include using callipers to measure waist circumference or skin thickness in specific areas of the body, such as under the shoulder blades and the back of the upper arm.

Screening for health risks with BMI

Beyond diagnosing weight types, BMI also serves as a screening tool for assessing health risks associated with weight. Different BMI categories correlate with varying degrees of health risk:

• Underweight: Individuals with a BMI less than 18.5 may be at risk for infertility, malnutrition, weakened immune function and osteoporosis.
• Normal weight: Falling within the healthy BMI range of 18.5 to 24.9 indicates a lower risk of weight-related health problems as compared to other BMI categories.
• Overweight: A BMI of 25 to 29.9 increases the risk of developing conditions such as hypertension, type 2 diabetes, heart disease, and certain cancers.
• Obesity: BMI 30 or a higher range significantly increases the risk of serious health problems, including cardiovascular disease, stroke, sleep apnea and joint problems.

Healthcare providers use BMI as a starting point to discuss potential health risks related to weight status. It informs discussions about lifestyle modification, like dietary changes and exercise routines, aimed at improving overall health and reducing the risk of chronic diseases related to weight.

Although BMI is a valuable screening tool, it does have some limitations. It does not directly measure the percentage or distribution of body fat, which can vary significantly from person to person. Therefore, individuals with a muscular build or higher muscle mass may have a higher BMI without necessarily having an unhealthy level of body fat.

Also, remember that many factors like genetics or lifestyle habits can also contribute to these health conditions even if your BMI is not high.

How do I calculate my BMI?

Now that we have understood what BMI is used for, let's understand how to calculate BMI.

To calculate your BMI (Body Mass Index) in kilograms, divide your weight in kilograms by your height in meters squared.

The formula is BMI = weight (kg) / height^2 (m^2).

For example, if you weigh 70 kilograms and your height is 1.75 meters , the calculation is 70 / (1.75 x 1.75) = 22.86.

This result places you in the normal weight category (18.5 to 24.9 BMI) on the BMI chart, providing a general indication of your weight status relative to your height.

What is a healthy BMI?

According to the World Health Organization, a healthy BMI range lies between 18.5 and 24.9. But remember, it is not just about the number! Your overall health is determined by many factors like genetics, activity levels, lifestyle habits including smoking or drinking alcohol, and mental health conditions.

What are the limitations of BMI?

While BMI is an easily accessible tool for assessing an individual's body fat estimation it does have a certain limitations.

Limitations of using BMI to help diagnose weight types

The fundamental drawback in using BMI for diagnosing weight type is that it does not differentiate between lean body mass (the weight of everything in your body except fat) and fat mass, which means that a muscular person can have a high BMI despite having low body fat, and vice versa.

Additionally, the same BMI chart is used for both males and females, even though females generally have more body fat than males. The table also does not take into account average changes in adult height over time, or specific population groups such as athletes, the elderly, pregnant women, or people who suffer from muscle wasting due to medical conditions.

Limitations of using BMI as a screening tool for health conditions

Using BMI as a health risk assessment tool also has its limitations. It does not measure where or how body fat is distributed; having excess fat in your abdomen vs thighs impacts your health differently.

The link between BMI and mortality rate also often overlooks other factors such as family history of diseases, lifespan or history of cancer.

Conclusion

Understanding the body mass index (BMI) can be an essential step to understand your weight and wellness better. It is a useful tool for obtaining a general idea of ​​your body fat, but it is crucial to remember that it is only part of the puzzle. Your overall health is influenced by various factors, including genetics, lifestyle, mental well-being and much more.

If you are concerned about your BMI and what it means for your health, don't hesitate to reach out to healthcare professionals. At Metropolis Healthcare, we strive to assist you on your journey to wellness. With our advanced diagnostic labs and qualified technicians ready for at-home sample collection, we ensure that prioritising your health has never been easier!