Body Mass Index (BMI) is a simple ratio of height and weight. It has become a measure of health, specially for doctors and insurance companies.
If you are above a certain level of BMI you are considered obese. You need to be within a certain level to be healthy. BMI does not consider muscle mass, bone density, overall body composition, and racial and sex differences and that is why it is an inaccurate measure of body fat content.
Obesity is a problem and BMI helps in deciding who is obese. Obesity increases the risk of developing type 2 diabetes, heart diseases, cancer, sleep apnoea and other diseases and conditions. However, it may protect against threats from all causes and that due to stroke, heart failure and diabetes.
However, a study published in 2016 in the International Journal of Obesity found that millions of people are termed as obese are actually healthy when the data for their blood pressure, blood sugar, cholesterol and similar test taking into consideration. Similarly, many people with normal BMIs were found to be unhealthy.
So, is your BMI a lie?
BMI is not everything
BMI is not everything because it is as good as your height and weight. It cannot be the only deciding factor of health. BMI is not curious when height and weight are self reported.
Even though it is not a great indicator for insurance companies to charge people more fees if they have a higher BMI, however the companies do that.
BMI alone should not be used for making medical decisions. And many doctors are not doing that. They also consider other factors to decide whether a person is fit and healthy.
Waist size and diabetes risk
Waist size is linked to diabetes risk, regardless of BMI. Scientific studies link waist circumference is with type 2 diabetes risk. According to a scientific study done on the subject in non-obese, overweight male with a waist circumference of at least 40.2 inches has the same or higher risk of type 2 diabetes as an obese male.
Many people believe body composition is a better measure of overall health. However, it can be better but it's very difficult to measure. Not all people have access to body composition measures and facility to measure. The percentage of body fat in combination with overall weight is the body composition measurement. It can be a better measure than wait for BMI alone while predicting morbidity and likelihood to develop diseases.
BMI is important
We cannot ignore BMI, but we should not overestimate its value. If you believe that anyone with BMI of 30 is ill at the moment, that can be a misconception because it is not true.
Weight has a cumulative effect on health. It will also depend a lot on the age of the person. For example, a person 20 years old with a BMI of 30 is less likely to be sick when compared to a 50-year-old person with a BMI of 30.
We also used BMI in weight loss surgery. It has been for a long time as one of the major indicators for surgery.