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Everything You Need to Know About BMI

Body Mass Index (BMI) is defined as the measurement of a person’s weight to his or her height. It’s rather an indicator of weight than a direct measurement of a person’s healthy body composition.

BMI is used for the initial screening of people in high weight categories. It’s often used to prevent the risk of health complications. But, recent research has shown how BMI fails to provide actual information on body composition and health. In this article, we will cover the basics of BMI, how we can calculate it, and why BMI is an inadequate indicator of good health. 

History of BMI

To correctly understand the application of BMI, we should know about its roots. If we go into its history, it looks like it was first introduced around 200 years ago by a Belgian mathematician named Adolphe Quetelet. A point to note here is that he was a mathematician and not a physician. 

The reason behind the introduction of BMI is that the government needed statistics regarding the obesity of the general population. The process had to be simplified and cost-effective, and hence Quetelet came up with a simple formula.  

According to Quetelet, BMI was a way of measuring populations, and not individuals. This is one of the reasons why BMI tends to be an incorrect indicator of healthy weight. 

How Do You Calculate BMI?

Body Mass Index is calculated using a person’s height and weight. In the metric system, the formula is BMI = kg/m2 where kg is a person’s weight in kilograms and m2 is their height in square meters.

If you would like to have a more comprehensive BMI test, you can try such BMI calculators online that factor in gender and age. 

Interpreting BMI 

According to CDC, a normal BMI for an individual above 20 years of age ranges between 18.5 and 25. A BMI between 25 and 30 is categorized as overweight. In case the BMI is over 30, it indicates obesity. 

However, BMI is just one factor in the overall picture of your health. Even if your BMI falls into the normal weight category, you still have a higher risk of health problems if you:

  • Smoke regularly
  • Have high LDL cholesterol 
  • Pick low foods of low nutritional value 
  • Lack of regular physical activity

Doctors and researchers are diligently working towards novel advances to improve the measurement of the optimal weight for an individual. Besides, these methods would increasingly factor in sex, age, genetics, medical conditions, and metabolic parameters

Is it Crucial to Keep a Check on BMI for Weight Loss? 

As mentioned above, BMI is not a perfect method for measuring weight loss. For example, an increase in muscle mass might still push your BMI towards being overweight. In addition, it may not be a good health measure for teenagers or the elderly.

When you’re trying to lose weight, your focus should be on your fat loss and not on BMI. Oftentimes, there’s a chance that you will initially gain weight due to an increase in lean muscle. Therefore, if you measure your BMI, you’re most likely to see an increase. 

Instead of this, methods like the Weight-to-height ratio, Waist circumference, Waist-to-hip ratio, and Body fat percentage can be more reliable trackers of weight loss. 

Some Drawbacks of BMI You Should Know 

Ignores Fat Distribution 

When it comes to greater health risks, the location of fat on the body makes a significant difference. According to a Johns Hopkins study, individuals with fat stored around their lower waist area have a greater risk of chronic diseases than those with fat stored in their hips, buttocks, and thighs. 

BMI doesn’t consider fat distribution and oversimplifies the calculation by merely using weight and height, making it an unreliable predictor of health. 

Doesn’t Consider Biological Differences

Men and women have different fat percentages. Generally, females have a greater percentage of body fat than males. Other than this, BMI also doesn’t regard conditions like pregnancy, old-age, menopause, and other medical conditions. 

Based on Assumptions

BMI doesn’t distinguish between lean mass and fat. A person may be perfectly fit but have a high muscle mass, making them heavier on the scale. It simply assumes that those with high BMI are overweight without considering the origin of this weight.  

Contributes to Weight Bias

People often remain stuck on their BMIs because they don’t consider other factors associated with healthy living. This weight bias is also noticed when an overweight individual visits a doctor.

When there is excessive focus on weight and BMI, there can be a disregard of the patient’s concerns or underlying conditions that have contributed to the weight gain. 

Doesn’t Factor Bone Mass 

Many people have dense bone mass and that pushes them towards the heavier end of the weighing scale. BMI doesn’t factor in bone mass. A person with high bone mass measuring their BMI might find it as an incorrect method of measurement. 

These flaws make it imperative for people to not solely depend on BMI as an indicator of individual health. 


BMI is good for pinpointing important conditions that become more likely when a person is overweight or obese. However, BMI is best used for statistical purposes and it’s not an adequate indicator for predicting how healthy an individual is. 

All in all, it’s beneficial to know your BMI. However, you shouldn’t base your health-related decisions only on BMI. 


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