Although it has been considered for decades as a benchmark measure, it has also been widely criticized for its oversimplification.
Currently many scholars consider it obsolete, imprecise and not usable in medical and fitness contexts, while others claim its validity.
Let's try to clarify.
in square meters.- BMI = weight (kg) / height (m2)
Once the BMI is calculated, it is compared to the BMI scale to determine if the person is within the "normal" weight range.
Range of BMI Classification Health Hazard
Less than 18.5 High Underweight
18.5–24.9 Normal Weight Low
25.0–29.9 Overweight Low to moderate
30.0–34.9 Moderately obese High
35.0–39.9 Severely obese Very high
Over 40 Extremely obese Extremely high
While this rating can provide a snapshot of a person's health, it does not take into account other factors, such as age, gender, ethnicity, genetics, fat mass, muscle mass, and bone density.
A 2017 study of 103,218 deaths found that those who had a BMI of 30.0 or higher had a 1.5-2.7 times greater risk of death after a 30-year follow-up.
Another study showed that people in the "obese" BMI category had a 20% increased risk of death from heart disease, compared to those in the "normal" BMI category.
The researchers also found that the underweight or severely and extremely obese had died on average 6.7 years and 3.7 years earlier, respectively, compared to those who fell into the "normal" BMI category.
Having a BMI greater than 30.0 also appears to significantly increase the risk of chronic health problems, such as type 2 diabetes, heart disease, breathing difficulties, kidney disease, non-alcoholic fatty liver disease, and mobility problems.
In contrast, a 5-10% reduction in a person's BMI has been associated with reduced rates of metabolic syndrome, heart disease, and type 2 diabetes.
, blood sugar, heart rate values, blood pressure, inflammation levels and many more.Also, as a person ages, their body naturally increases fat mass and decreases muscle mass.
Numerous studies have shown that a higher BMI of 23.0-29.9 in the elderly is not only normal but may be protective against early death and various types of diseases.
Finally, simply using the BMI to determine a person's health ignores other non-medical but equally important aspects such as mental well-being, quality of social interactions, income, access to quality and affordable food, and living environment.
Assumes all weight is equal
Although one kilogram of muscle weighs as much as one kilogram of fat, muscle is denser and takes up less space.
As a result, a person can be very thin but have high muscle mass, which makes them heavier on the scale.
Two people of the same height and weight might therefore look completely different: one similar to a bodybuilder with "high muscle mass," while the other with greater fat mass.
Considering only the BMI, you run the risk of classifying both equally.
It does not consider the distribution of fat
Although a BMI that is too high is linked to worse health conditions, the position of fat on the body can make a difference.
The one located around the stomach area, in fact, carries a greater risk of chronic diseases than the one that accumulates on the hips, buttocks and thighs.
It may not be relevant to all populations
Despite the widespread use of BMI among all adults in the world, this tool may not accurately reflect the health of some ethnic groups.
For example, extensive research has shown that people of Asian descent have a higher risk of chronic disease at lower BMIs than Caucasians.
Additionally, darker-skinned populations can be misclassified as overweight despite having lower fat mass and higher muscle mass. This may suggest that the risk of chronic disease occurs at a higher BMI level, compared to other ethnicities, especially among women.
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