Body mass index (BMI) is a term that you will hear used by health professionals and trainers. This calculation charts obesity throughout a particular population. Many people worry about their BMI, and they want to stay in a healthy range. This index can determine whether a patient is underweight or overweight. But how did it originate? Here’s a look at the origins and uses of the body mass index.
Quetelet and BMI
In the 1830s, Lambert Adolphe Jacques Quetelet developed a simple math formula. Quetelet became fascinated with the measurements of the human body. During this time, he coined the concept of the “average man” and created a formula for body mass. A person’s healthy weight (kilograms) was divided by their height in meters squared. While Quetelet developed the method for body mass, it did not become popular until later centuries.
In his quest for the ideal body type, Quetelet gathered information on the height and weight of several populations. He was the first person to create an equation that relates height to weight. This standard is known for indicating obesity, and it is referred to as “Quetelet’s Index.” While Quetelet had no interest in determining obesity, his name is now closely tied to the obesity index with most medical professionals.
Determining Obesity in the 20th Century
During the mid-20th century, scales become more readily available for home use. With these products, insurance companies started to compile data on their customers. Many insurance companies associated excess weight with a decrease in life expectancy, so it was critical for insurance companies to gain this information. However, these tabulations were often flawed with no attempt to standardize the results. When these people reported their weight, they measured in shoes and clothing that often distorted the results.
By the early 1940s, Metropolitan Life Insurance Company created its tables for desirable weight. In these charts, the person’s age was not a factor, but the individual’s body frame played a significant role. Healthy weight was based on a small, medium, or large body frame. Metropolitan Life would revise these tables over the years. However, their tables would be the benchmark for weight and body mass for the next few decades. Some physicians even referred to these charts to determine if a patient was at a healthy weight. During this time, Quetelet’s Index was ignored by many professionals in the medical field.
“The Varieties of Human Physique” by William H. Sheldon was the first book to use the term “index of body mass.” This book also called BMI a “ponderal index.” Sheldon would classify body types into three different classes, including ectomorph, endomorph, and mesomorph. In his book, he used a separate calculation for body mass that included height in meters divided by weight in kilograms cubed.
The first use of the term “body mass index” appeared in the 1959 paper by Alberto DiMascio. While this study included “BMI,” it was a research paper on the somatotypes of dogs. DiMascio also used another ratio for weight to height, but he completely ignored any mention of Quetelet. Scientific literature throughout the 1960s would make brief references to the formula of Quetelet. However, no one would use his calculations to determine obesity.
Quetelet’s Measurements Gain Popularity
In 1972, Ancel Keys wrote a paper known as “Indices of Relative Weight and Obesity.” Keys believed that Quetelet’s index was superior to all other methods. His team concluded that the index was accurate after they compared measurements of fat with skin calipers and underwater weighing procedures. This study took body measurements from 7,400 men from five different countries. During this time, he analyzed their subcutaneous fat thickness and adiposity-body density. In this study, Keys used the formula created by Quetelet to measure body mass according to the person’s weight and height.
With obesity becoming a problem in the country, epidemiologists started to use the Keys’ version of body mass index to track health issues among the general population. For these reasons, BMI has become popular with researchers and the government to monitor health risks in the United States.
By 1985, obesity in the United States was measured with BMI by the National Institutes of Health (NIH). The NIH originally had broad categories for body mass index. By 1998, the NIH classified BMI into several categories, including all ages, cultures, and both sexes. That standard has been in use to the current day. Over the years, the cut-off values for obesity have become more stringent. In turn, many more people have been labeled as obese and overweight.
Some Flaws in This Method
However, BMI is only an estimate of adipose tissue in the body. These indexes cannot differentiate fat from muscle in the body. In some populations, the BMI can be inaccurate. However, BMI is simple to use and often the preferred method to measure obesity. You will often see a BMI chart in most physician’s offices as it only requires a tape measure and scale to measure height and weight.
In today’s modern world, we have updated technology to calculate body mass. People come in all different shapes and sizes. They grow at different rates. In 2013, an Oxford University mathematician called the current BMI as a “bizarre measure.” He argued that the index is “confusing” and “misinformed.” The calculations can divide too much weight for shorter people and too little for taller individuals. As a result, these individuals are receiving incorrect body indexes.
Despite all the new technology and calls for a new index, the BMI is still the standard to measure a body’s level of obesity. While many researchers are trying to design a new rule, the simple formula from Quetelet still reigns supreme. However, don’t let the BMI be your only source for measuring fat. You can use this index in conjunction with other measurements to determine if your body is in a healthy range.
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