Body Mass Index: Is it the Right Tool for Health?
Body mass index (BMI has been used for decades to assess health and weight status. However, a closer examination reveals that BMI may not be as reliable as once believed. In this article, we delve into the historical context of BMI, uncover its limitations, examine the influence of pharmaceutical companies, explore research findings that challenge its validity, and shed light on the motivations behind its continued use. By doing so, we emphasize the importance of adopting a comprehensive, personalized approach to assessing health while combating weight stigma.
What Is Body Mass Index (BMI)?
Body mass index (BMI) is a simple calculation using height and weight to categorize individuals into ranges such as “underweight,” “normal weight,” “overweight,” and “obese.” While BMI is often treated as a proxy for health, it does not directly measure body fat, metabolic health, or overall well-being.
The Origins of Body Mass Index
From Quetlet’s Index to Modern BMI
BMI can be traced back to the early 19th century, when Belgian mathematician Lambert Adolphe Jacques Quetelet developed a formula to quickly and simply measure the weight of the general population and define the characteristics of a "normal man." His goal was to analyze population-level data, not to assess individual health.
How BMI Became a Medical Standard
Fast forward to the early 1900s in the United States, U.S. life insurance companies observed a higher rate of death for people (white, wealthy men) who were “overweight” using a ratio of weight and height that they developed into weight tables. However, subsequent research, encompassing larger and more diverse samples, revealed that individuals classified as "overweight" actually had lower mortality rates. Despite these new findings, insurance companies, driven by financial considerations, continued to emphasize weight as a determinant of premature death.
In 1972, researcher Ancel Keys, who disagreed with the insurance weight tables and aimed to find an alternative approach to evaluate body mass, suggested renaming the Quetelet Index as the Body Mass Index (BMI). Keys proposed using Body Mass Index scales to investigate and establish connections between health, disease, and "obesity."
In 1998, the National Institutes of Health (NIH) lowered the threshold for the "overweight" BMI category to 25 for both men and women, from 28 for men and 27 for women. As a result, millions of people were suddenly categorized as "overweight" overnight. This decision was based on a 1996 report by the International Obesity Task Force (IOTF), which recommended lowering the BMI category of "overweight." Interestingly, the primary funders of the IOTF report were Hoffmann-La Roche and Abbott Laboratories, two pharmaceutical companies that produce weight-loss drugs. Moreover, many of the researchers and scientists who served on the WHO and NIH committees were being paid by various weight-loss drug companies. These companies had a vested interest in classifying more Americans as "overweight," thereby creating a much larger market for their weight-loss drugs.
This brings us to the widely recognized and utilized measurement that persists today. Keeping this timeline of the BMI in mind, I want to take a deeper look at what this all means and all of the moving parts involved.
Why BMI is a Flawed Measure of Health
Outdated Data and Narrow Populations
To begin, one of the most significant flaws in BMI is its age. BMI is based on data from the 1830s, long before modern medicine, nutrition science, or an understanding of metabolic health existed. The original formula does not reflect today’s diverse population and excludes factors such as race, sex, age, and genetics. His data was derived solely from a specific European white male population, which represents only 30% of the current US population.
Next, let's delve into Quetelet's creation of the BMI formula. While Quetelet's intentions were well-meaning, his scientific methods had some questionable aspects. Quetelet had to alter the formula to fit his data, a practice that runs counter to proper statistical methodology and is considered a flawed approach.
BMI was Never Meant for Individual Health
The BMI formula fails to consider crucial factors such as age, sex, body frame, body composition, and the natural changes in body mass that occur with age. It also makes no distinction between the relative proportions of bone, muscle, fat, and fluid in the body, which vary naturally from person to person. Bodies are supposed to change in different stages of life. That is normal, natural, and a part of being human.
What is Body Mass Index Really Measuring?
What Research Tells Us About BMI and Mortality
A notable large-scale study conducted in 2013 involving 40,000 participants revealed fascinating findings. It showed that individuals falling within the "obese" BMI range had the same risk of death as those with "normal" BMIs, while those classified as "overweight" actually had a lower risk of death compared to all other BMI categories. Surprisingly, the highest risk of death was observed among individuals categorized as "underweight."
Findings also showed that individuals with "obese" BMIs living with type 2 diabetes, high blood pressure, cardiovascular disease, or chronic kidney disease had longer life expectancies than their thinner counterparts with the same conditions. Additionally, when examining individuals over the age of 55, those with BMIs in the "overweight" and "obese" categories exhibited a decreased risk of death compared to individuals with "normal" and "underweight" BMIs.
Metabolic Health vs. Weight Categories
Another compelling study discovered that nearly half of those classified as "overweight" and one-third classified as "obese" were metabolically healthy. This means that despite their higher BMI, these individuals had normal readings for key health indicators, including blood pressure, cholesterol, and blood sugar levels, indicating good overall health. Conversely, almost one-third of those in the “normal” weight BMI category were found to be metabolically unhealthy. These findings highlight that BMI does not reliably reflect metabolic health or disease risk.
Why Does the Medical Community Still Use Body Mass Index?
Despite BMI's limitations and flaws, the medical community continues to use it for several reasons. One primary factor is the simplicity and cost-effectiveness of calculating BMI. It involves a straightforward calculation based on height and weight, making it a tempting tool for “assessing health.”
Another significant influence is the lobbying efforts of the medical insurance industry. Insurance companies have a vested interest in maintaining the use of BMI, as it can be a factor in determining insurance premiums. AKA, insurance companies can penalize individuals with higher BMI regardless of actual health, prioritizing profit over individualized care.
Moving Beyond BMI: A Weight-Inclusive Approach to Health
The Body Mass Index (BMI) has proven to be a flawed and problematic measure for assessing an individual's health and weight status. It ignores body composition, metabolic markers, life stage, and social determinants of health, while reinforcing harmful weight-based assumptions. Moreover, the history and influences behind the development and perpetuation of BMI reveal the role of profit-driven interests and weight stigma in shaping its continued use. It is crucial to recognize BMI's limitations and advocate for a more comprehensive, personalized approach to assessing health that considers a range of factors beyond weight alone. By embracing a HAES approach and promoting equity for all bodies, we can foster a more inclusive perspective that prioritizes well-being for all.
Ready to explore a more personalized approach to your nutrition and health? Contact our expert dietitians at CV Wellbeing for a consultation tailored to your unique health needs, not a number.
Why do we use quotation marks around the words "obese" and "overweight"?
These terms have been coined by the medical community to pathologize and label individuals based on their body size. By using quotation marks around "overweight," we acknowledge that it implies an arbitrary notion of a "correct" weight that everyone should adhere to, as dictated by flawed and problematic BMI charts. Similarly, the term "obese" is enclosed in quotation marks because it assigns illness solely based on size, inaccurately assuming that weight is the sole determinant of one's health and wrongly placing blame on the individual. By using quotation marks, we bring attention to the underlying biases and harmful implications associated with these terms, fostering a critical examination of the way we perceive and discuss body weight and its impact on health.
