By JOHN RICHARD SCHROCK
Our active duty U.S. Air Force needed 26,877 new airmen this last fiscal year. They only recruited 11,200. As a result, the Air Force Recruiting Service announced in early April that they have raised the maximum body fat for males from 20 to 26 percent, and for females from 28 to 36 percent. While the prior levels were within normal range, the new upper limits now allow in individuals who are obese as defined by the American Council on Exercise and graphed on a Body Mass Index.
Indeed, all branches of service face this problem. An earlier Johns Hopkins University study found over half of 18-to-25 year olds were overweight or obese. The percent in this age range who were of normal weight dropped from near 70 percent in 1976 to 34 percent in 2018. According to the CIA, only a handful of small Pacific island nations exceed the U.S. in rates of obesity.
But what exactly is a Body Mass Index and how are “overweight” and “obese” scientifically defined?
The concept was developed by Lambert Adolphe Jacques Quetelet (1796–1874), a Belgian mathematician who applied science to social conditions in a field he called “social physics.” It was obvious to him that a short person who was a certain weight could be fat while another much taller person with that same weight would be underweight. He therefore produced the Quetelet Index based on “'the weight increases as the square of the height.” It is calculated by dividing a person's weight in kilograms by the square of height in meters (or weight in pounds by height in feet, in backwards America). Therefore, a person who weighs 150 pounds is underweight if six-and-a-half feet tall, of normal weight if 5 feet, 11 inches tall, and overweight if 4 feet, 11 inches tall.
If this math formula calculates you as under 18.5, you are underweight. A figure from 18.5 to 25 is a normal range. Overweight scores are from 25-30. But over 30 is obese. Quetelet merely used this early calculation as a descriptor. He did not make any medical proclamations.
Modern use of the term BMI and its connections with health was addressed by Ancel Keys (1904-2004) and colleagues in a 1972 article in the “Journal of Chronic Diseases.” Keys was a pioneer researcher who discovered that different kinds of fats had different effects on human health.
Earlier in his life, Keys had been drawn into the development of military rations that could be stored and distributed during warfare. He secured the initial ingredients from a local Minneapolis grocery store and produced a preserved meal that weighed only 28 ounces but held 3200 calories. Ingredients included dried biscuits and sausage, hard candy and chocolate. It became known as “K-rations.” The Cracker Jack company provided the packaging. Similar to MREs (meals ready to eat) today, this became a mainstay of military life in the field. Keys would also promote what is today called the Mediterranean diet.
Keys found the Body Mass Index important in dietary medicine, and “...at least as good as any other relative weight index as an indicator of relative obesity.” He also was very concerned with the aftermath of warfare that left many civilians starving. The BMI was an important part of his research into how the body responds when daily food intake drops far below what is normal for maintaining normal weight. His work with colleagues produced a classical two-volume study on “The Biology of Human Starvation” in 1950 and contributed to refining the “set point” theory.
But starvation is not the problem that the U.S. is now facing. A growing number of our children lack regular exercise. This is made worse by their sedentary attention to smartphones, hand-held games and laptops. Overall reduced activity levels became worse during the pandemic although the majority of our next generation were already overweight or obese.
The U.S. is likewise the only developed country that has not turned around the recent temporary decline in life expectancy caused by the pandemic. For the United States, our life expectancy decline preceded the pandemic, mainly caused by record drug overdoses but also by increases in deaths due to diseases that accompany being overweight and obese.
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Sources: Keys, A; Karvonen, N; Kimura, N; Taylor, HL. 1972. “Indices of relative weight and obesity.”
Journal of Chronic Diseases, 25: 329–343. Reprinted in: International Journal of Epidemiology, 2014; doi:10.1093
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John Richard Schrock has trained biology teachers for more than 30 years in Kansas. He also has lectured at 27 universities during 20 trips to China. He holds the distinction of “Faculty Emeritus” at Emporia State University.