The complete guide to BMI

Overview
A common statistic used by healthcare facilities to evaluate their patients’ health is body mass index (BMI). It has been used as the benchmark for assessing health based on body size for decades, yet it has continually drawn criticism for its oversimplification of what being healthy actually entails. In fact, a lot of people claim that because BMI is outdated and imprecise, it shouldn’t be applied in medical or fitness contexts.

You can learn everything you need to know about BMI from its history to how well it can predict health on this blog.

Background Of BMI

Body mass index is referred to as “BMI.” It was invented in 1832 by Lambert Adolphe Jacques Quetelet, a Belgian mathematician.

He created the BMI scale to assist governments in quickly determining the prevalence of overweight and obesity in a society. They were able to devote resources for money and health thanks to this.

Curiously, Quetelet said that utilising BMI to evaluate the overall health of a community was superior to using it to research a single individual. However, it is frequently employed to assess people’s health.

Is BMI a Reliable Health Indicator?

Despite worries that BMI doesn’t accurately identify whether a person is healthy, the majority of research shows that a person’s risk of chronic illness and early death does increase with a BMI lower than 18.5 (“underweight”) or 30.0 or over (“obesity”).

For example, a 2017 retrospective study of 103,218 deaths revealed that those with a BMI of 30.0 or above (referred to as “obesity”) had a 1.5–2.7-fold increased risk of passing away after a 30-year follow-up.

Those with an “obese” BMI had a 20% greater risk of dying from any cause including heart disease than those with a “normal” BMI, according to a second study involving 16,868 people.

Furthermore, the researchers found that, compared to those with “normal” BMI, those with “underweight” and “severely obese” or “extremely obese” BMIs died, respectively, 6.7 and 3.7 years earlier. Other studies have shown that having a BMI above 30.0 significantly increased the risk of suffering from chronic illnesses such as type 2 diabetes, heart disease, breathing issues, renal sickness, non-alcoholic fatty liver diseases, and mobility issues.

Additionally, a 5–10% decrease in BMI has been associated with a decreased risk of type 2 diabetes, metabolic syndrome, and heart disease.

Since most studies show that people who are obese have a higher risk of acquiring chronic illnesses, many health practitioners can utilize BMI as a general indication of health.

How Is BMI Calculated?

The BMI scale is based on a mathematical formula that compares a person’s height in meters squared to their weight in kilograms to determine if they have a “healthy” weight

Height / Weight (kg) = BMI (m2)

Alternately, you may determine BMI by multiplying 703 by the product of your weight in pounds and your height in square inches:

Weight (lbs) x Height (in2) x 703 equals BMI.

A BMI calculator that is available online, such as the one from the National Institutes of Health, is another option. If you fall within the “normal” weight range, your BMI is computed and then compared to the BMI scale.

BMI-Related Issues

Despite evidence connecting low (below 18.5) and high (over 30) BMI with increased health risks, there are significant issues with BMI usage.

Assumes that all weights are equal.

Even though 1 pound or kilogram of muscle weighs the same as 1 pound or kilogram of fat, muscle is denser and takes up less space. Therefore, a person who is thin yet has a lot of muscle may weigh more than a normal person.

For instance, someone who weighs 200 pounds (97 kilograms) and is 5 feet 9 inches (175 cm) tall, and has a BMI of 29.5 is regarded as “overweight.”

If BMI is the only factor considered, it is quite easy to mistakenly label someone as “overweight” or “obese” despite their low-fat mass.

As a result, in addition to weight, it is crucial to take into account a person’s muscle, fat, and bone mass.

Possible weight bias

Medical professionals are expected to apply their best judgment, which means that they will take the BMI result and treat each patient as an individual.

However, some medical practitioners simply utilize BMI to assess a patient’s health before making recommendations, which can result in weight prejudice and subpar medical care.

Higher BMI patients more frequently claim that their doctors only address their BMI during appointments for unrelated issues.

Serious medical conditions frequently go undiagnosed or are misdiagnosed as weight-related disorders.

In reality, research has shown that those with higher BMIs are less likely to have frequent health checks because of anxiety about being assessed and mistrust of the medical system.

additional unaddressed health issues

BMI merely indicates whether or not a person is a “normal” weight without taking into account their age, sex, heredity, way of life, prior medical conditions, or any other factors.

By ignoring other crucial health indicators such as cholesterol, blood sugar, heart rate, blood pressure, and inflammatory levels, such as BMI, one may overestimate or underestimate their genuine health.

Additionally, the BMI employs the same formula for both sexes despite the fact that men and women have different body compositions (men having higher muscle mass and less fat mass than women)

A person’s muscle mass gradually decreases and their body fat naturally grows as they age. Numerous studies have demonstrated that older adults with a BMI between 23 and 29.9 can be protected against disease and early mortality.

Last but not least, evaluating a person’s BMI alone to assess their health ignores other factors including mental health and complex socioeconomic issues.

Conclusion

The hotly debated body mass index (BMI) approach is used to determine a person’s risk for poor health and excess body fat.

The majority of research shows that as BMI rises above the “normal” level, the chance of developing a chronic illness increases. Furthermore, negative health effects have been related to low BMIs (below 18.5).

BMI, however, ignores other factors including age, sex, fat mass, muscle mass, race, genetics, and medical history that may have an impact on health.

When employed as the sole indicator of health, BMI has also been found to aggravate weight bias and health disparities. BMI is a terrific place to start, but it shouldn’t be your primary measure of health.

Author: Prachya

References

• Klatsky, A. L., Zhang, J., Udaltsova, N., Li, Y., & Tran, H. N. (2017). Body Mass Index and Mortality in a Very Large Cohort: Is It Really Healthier to Be Overweight? The Permanente Journal, 21, 16–142.
• Aune, D., Sen, A., Prasad, M., Norat, T., Janszky, I., Tonstad, S., Romundstad, P., & Vatten, L. J. (2016). BMI and all cause mortality: systematic review and non-linear dose-response meta-analysis of 230 cohort studies with 3.74 million deaths among 30.3 million participants. The BMJ, 353.
• Borrell, L. N., & Samuel, L. (2014). Body Mass Index Categories and Mortality Risk in US Adults: The Effect of Overweight and Obesity on Advancing Death. American Journal of Public Health, 104(3), 512.
• Abdelaal, M., le Roux, C. W., & Docherty, N. G. (2017). Morbidity and mortality associated with obesity. Annals of Translational Medicine, 5(7).
• Han, T. S., & Lean, M. E. (2016). A clinical perspective of obesity, metabolic syndrome and cardiovascular disease. JRSM Cardiovascular Disease, 5, 204800401663337.
• Ye, M., Robson, P. J., Eurich, D. T., Vena, J. E., Xu, J. Y., & Johnson, J. A. (2018). Changes in body mass index and incidence of diabetes: A longitudinal study of Alberta’s Tomorrow Project Cohort. Preventive Medicine, 106, 157–163.
• Brown, J. D., Buscemi, J., Milsom, V., Malcolm, R., & O’Neil, P. M. (2016). Effects on cardiovascular risk factors of weight losses limited to 5–10 %. Translational Behavioral Medicine, 6(3), 339.
• Grier, T., Canham-Chervak, M., Sharp, M., & Jones, B. H. (2015). Does body mass index misclassify physically active young men. Preventive Medicine Reports, 2, 483.
• Jayedi, A., Soltani, S., Zargar, M. S., Khan, T. A., & Shab-Bidar, S. (2020). Central fatness and risk of all cause mortality: systematic review and dose-response meta-analysis of 72 prospective cohort studies. BMJ (Clinical Research Ed.), 370.