Body mass index Archives - Heartland Health Research Institute

This series on obesity continues with the discussion of body mass index (BMI), and whether BMI is over-valued when assessing the health of individuals.

BMI is a medical calculation that is almost 200 years old. Developed in 1832 by a Belgian mathematician, Lambert Adolphe Jacques Quetelet, the BMI was designed to quickly estimate the degree of overweight and obesity in a defined population that would help governments decide the allocation of health and financial resources. Quetelet believed the BMI was useful only in providing a snapshot of a population’s overall health – his intent was not to measure the health of single individuals.

BMI is derived from your height and weight, calculated by dividing weight (in pounds) by height (in inches squared) and multiplying by 703. If you’re curious, you can quickly learn your own BMI here. Once calculated, the BMI is compared to the BMI scale, which is broken down into five categories:

Underweight: BMI below 18.5
Normal: BMI ranging between 18.5 and 24.9
Overweight: BMI between 25 and 29.9
Obese: BMI of 30 or higher
Severe Obesity: BMI of 40 or higher

Is BMI Outdated?

Critics believe BMI is being overused and not very useful when analyzing the health of individuals. In fact, BMI is considered too simplistic, if not misleading. The critics make a number of points, including the following factors:

Fat versus Muscle – Some people have high BMIs, but not much body fat. One prime example is an athlete, such as a football player. This athlete can have high muscle tissue (and low body fat) which pushes up his weight – and his BMI number.
Activity Level – An individual who is very inactive, has lots of body fat and low levels of muscle and bone, may have a BMI in the normal range. But this individual is often elderly, in poor shape and sometimes sick. However, this individual with a ‘normal’ BMI has risks similar to people who carry a high amount of body fat and have a high BMI. These underlying risks are not reflected in the BMI score.
Body Type – The location of your fat can make a big difference to your health. The belly fat (apple shape) type is generally at higher health risk, and the chance of heart disease and type 2 diabetes increases. This fat settles around the waist instead of the hips. Likewise, fat that appears on the hips and thighs (pear shape) is not considered to be as harmful. BMI does not indicate the location of fat and, therefore, does not reflect those risks.
Age – As one ages, they may carry a little more weight, which may actually be beneficial. One possible reason is that as we age, a little extra weight can serve as reserves to draw on when fighting an illness. Because of this, an ideal BMI score may change as one ages.
Ethnicity – The BMI can be different based on ethnic groups. For example, people from India face higher health risks at relatively lower BMIs. As mentioned earlier, the standard definition of overweight is a BMI of 25 – 29.9. However, people of Indian descent may begin to develop a risk of diabetes when the BMI is 21 or 22. Asian-Americans tend to develop health risks, such as diabetes, at lower BMIs than whites. In other words, a healthy BMI for Asians ranges from 18.5 to 23.9, which is one point lower than the standard range. Asians are considered obese at 27 or higher. Compared to whites with the same weight and BMI, African-Americans may have less fat around their organs and more muscle mass. This means that African-Americans, despite having a high BMI, may have fewer health risks than whites.

These five factors give credence to the argument that BMI is both outdated and inaccurate when assessing the health of individuals.

So why continue to use BMI?

The counter-argument to continue using BMI can be equally persuasive.

Despite the concern of accurately identifying whether a person is healthy, most studies do link low and high BMI scores with a person’s risk of chronic disease and premature death. As an example, a 2017 study of 103,218 deaths found that people who had a BMI of 30 or greater (“obese”) had 1.5 to 2.7 times greater risk of death after a 30-year follow-up.

A 2014 study that included 16,868 people showed that “obese” BMI individuals had a 20 percent increased risk of death from all causes and heart disease when compared to those in the “normal” BMI range. From this same study, researchers found that people in the “underweight” category and the “severely obese” or “extremely obese” categories, died an average of 6.7 years and 3.7 years earlier, respectively, than those in the “normal” BMI category. Adults with a BMI greater than or equal to 40 are considered severely obese.

The data on BMI greater than 30 is quite substantial as it relates to the increased risk of chronic health issues such as heart disease, type 2 diabetes, breathing difficulties, kidney disease, non-alcoholic fatty liver disease, and mobility issues. (See references below)

In short, having a 5-10 percent reduction in an individual’s weight has been linked to decreased rates of metabolic syndrome, heart disease, and type 2 diabetes.

Summary

Despite the criticism of BMI, one can safely assume that BMI may be more useful at predicting future health – rather than diagnosing the current health.

Standard BMI definitions of overweight and obesity were based on white populations, which differs from other races and ethnic groups. Because of this, BMI should not be the only diagnostic tool when estimating a person’s risk of developing various chronic diseases. Many alternative measurement assessment tools exist to determine obesity and related health issues. The Harvard T.H. Chan School of Public Health has listed such measurements here.

Though BMI oversimplifies the health of individuals, research suggests it can serve as an important barometer to estimate a person’s risk of chronic disease, risk of early death and metabolic syndrome.

It’s important to know your BMI, but it is equally important to recognize its limitations.

This post is the second in a five-part series. You can read “Obesity Requires Employer Attention and Focus – (Part 1)” here.

To stay abreast of healthcare-related issues, we invite you to subscribe to this blog.

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References:

Employers have a great deal on their plates, and much of it relates to the ongoing COVID-19 pandemic. Attracting and retaining workers has always been a challenge, but the pandemic-ravaged economy has nudged this to a whole new level of urgency. The COVID virus dangerously challenges the workplace in another way, and it requires long-term thinking by employers.

This challenge relates to obesity.

Obesity

As we have learned during the past 20 months of the pandemic, obesity is a worrisome risk factor for hospitalization and death for those with COVID-19. A March 2021 Morbidity and Mortality Weekly Report, prepared by the Centers for Disease Control and Prevention (CDC), revealed evidence of a relationship found between body mass index (BMI) and COVID-19 severity. Obesity rates have nearly tripled in the U.S. over the last 50 years (Source: USA Facts).

The CDC uses the BMI scale that relates weight with height to determine obesity level. For adults, a BMI over 30 qualifies as obese. It should be noted that BMI is not a perfect measure of one’s current health. More about this in the next blog.

COVID-19 highlights the many risk factors for people who are both overweight and obese. For employers, these risk factors should be of great concern when promoting a healthy and productive workforce. In fact, employers must double-down on their efforts to confront this long-term threat to the wellbeing of employees. Pandemic or not, the associated risks with having high-BMI numbers will not go away any time soon.

Iowa Obesity Rates

Based on new CDC 2020 Adult Obesity Prevalence Maps of 50 states, Iowa adults are in the top 16 states having the highest rate of obesity (35 percent or more). A 2018 survey by The Behavioral Risk Factor Surveillance System (BRFSS), which is part of the CDC, found that almost 70 percent of adult Iowans are considered to be either overweight or obese. Put another way, 34.1 percent are overweight while another 35.3 percent are obese. However, 2020 data reveals that Iowa’s obesity rate has risen to 36.5 percent. This new map shows how Iowa compares to all other states, including the District of Columbia and two U.S. territories.

Data from the 2020 U.S. Census Bureau shows that Iowa’s population was 3,190,369, of which 77 percent are adults aged 18 and over (2,456,584 total). Using 2018 BRFSS data, this means approximately 867,174 Iowa adults live with obesity, while another 837,695 have BMI numbers between 25.0 to 29.9 – which is considered overweight.

According to ConsumerProtect, which used CDC-based data, adult Iowans tend to move a bit more than their counterparts from other states, with ‘only’ 25 percent of adults engaging in zero physical leisure activities – ranking Iowa as the 31st state having the highest percentage of adults engaging in no activity. Kentucky was the state with the highest percentage of adults reporting no activity (34.4 percent).

Impact on Individuals and Employers

The risk factors of having a higher-than-healthy BMI number comes at a substantial cost. The aforementioned risk factors for obesity and excess weight on the individual include, but are not limited to, the following:

All-causes of death (mortality)
High blood pressure (Hypertension)
High LDL, low HDL cholesterol, or high levels of triglycerides
Type 2 diabetes
Coronary heart disease
Stroke
Many types of cancer
Mental illness such as clinical depression, anxiety, and other mental disorders
Body pain and difficulty with physical functioning

According to a 2016 report by Wellmark, “The Health of Iowans,” obesity is a common factor that contributes to the most costly conditions among Wellmark’s members in Iowa. For employers, obesity is both a sensitive and challenging issue and varies by industry. The associated costs for obesity are primarily twofold: 1) treatment-related expenses, and 2) reduced worker productivity. Treatment expenses are typically covered by employer-sponsored health insurance and workers compensation while reduced worker productivity adversely impacts employers through absenteeism, presenteeism and wage replacement due to disability. Together, both represent a drag on productive output and profitability – which adversely impacts local and state economies.

A 2014 report in the American Journal of Health Promotion found that an obese employee with a BMI of 35 has nearly double the risk of filing a short-term disability claim or a workers’ compensation claim than an employee with a BMI of 25. This report also revealed that morbidly obese employees cost an average of $8,067 per year in covered medical claims, sick days, short-term disability and workers compensation, which is more than double the cost for normal-weight employees ($3,830).

According to a 2018 Milken Institute report, the chronic diseases that result from obesity and excess-weight were estimated to cost more than $480 billion in direct healthcare costs and $1.24 trillion in indirect work loss costs in the U.S. Together, both costs are equivalent to 9.3 percent of the U.S. gross domestic product (GDP).

Summary

The pervasive nature of an overweight and obese population is a profound challenge to all Americans and to employers. Changing behaviors on dietary and physical activity is the desired goal, but is often met with disappointing results.

Depending on how incentives and disincentives are aligned with desired outcomes, implementation of wellness programs have had limited success for employers. Organizations must develop new, targeted approaches that are sensitive to their employees, yet impactful enough to provide positive outcomes.

My next installment will focus on the criticisms of BMI and its use as a measure of health.

This post is the first in a five-part series.

To stay abreast of healthcare-related issues, we invite you to subscribe to this blog.