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The well-known BMI index was not used to measure people's health in the early days of its birth. It was not until insurance companies linked weight to longevity that the BMI index was promoted as an authoritative health indicator. Since then, the idea that obesity is harmful to health has been deeply rooted in the hearts of the people, and it has also created a new era of anxiety.

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There are thousands of professional terms in physiology and medicine, most of which are obscure, but none of them can be "out of the circle" like the body mass index BMI (Body Mass Index). According to the definition of the World Health Organization, BMI is the basic index to measure the relationship between height and weight, which is usually used to determine whether adults are overweight or obese [1]. In daily life, BMI is especially regarded as the "gold standard" in the field of weight loss, while in academic circles, BMI is also widely used in obesity-related epidemiological studies.

However, in recent years, there have been a lot of doubts about BMI, mainly focusing on the question of "whether BMI continues to be applicable to all kinds of research". In January, six obesity care organizations in the United States issued a joint statement saying that "BMI, which is used to screen obesity, is no substitute for clinical diagnosis. BMI is not a measure of body fat. Even if we can determine the BMI value of an individual, race, age and other social factors may change the risk of disease." [2]

Figure 1. Six American obesity care organizations in the joint statement, source: American Obesity Association [2] in fact, BMI has a long history. From the beginning of creation to being introduced into the field of modern medicine, and finally linked to obesity research, the purpose and significance of BMI has experienced two hundred years of tortuous development. To understand the past of this index and understand its connotation, advantages and limitations, it is helpful for the academic circles to judge whether it can continue to serve scientific research, and for us in our daily life, it is helpful to treat the index rationally.

Quetelet's "perfect index" BMI was born in Europe in the 19th century, when it was not called the "body mass index", but the Quetelet index (Quetelet index), named after its creator Adolphe Quetelet.

Figure 2. The statue of Adolphe Quetelet is located at the Academy of Sciences Palace in Brussels, Belgium. Source: brusselsremembers.comAdolphe Quetelet was born in what is now the historic Belgian town of Gent in 1796, the fifth of nine children. In his childhood, he has shown great talent, especially in mathematics, and is also obsessed with the humanities. In 1815, Quetelet entered the then newly established University of Ghent, where he studied under the French mathematician Jean Guillaume Garnier and received his doctorate in science in four years.

At the beginning of the 19th century, Europe's most outstanding scientists set their sights on the sky, and whether a country could build telescopes and observatories became an important measure of its scientific status. In 1823, Quetelet successfully persuaded the Dutch government (then Belgium was not yet independent from the Netherlands) to provide financial funding to build an observatory in Brussels and was appointed director of the observatory. While the observatory was being built, he went to Paris, France, to carry out astronomical research. In Paris, he met the famous Joseph Fourier, Poisson é on Poisson and Pierre Laplace, followed them and devoted himself to theory of probability.

However, the plan could not keep up with the change. Quetelet, who was abroad, learned that a revolution had broken out in his country and that the observatory under construction was occupied by the revolutionary army. Prior to this, Quetelet did not care about the complexity of political science or the dynamics of human behavior. However, social unrest obviously affected the development of his personal scientific research career and became a turning point in his career. Quetelet originally planned to study the hidden patterns of celestial bodies in space, but social upheaval led him to set a new goal: to use the mean analysis method (method of averages) used in astronomy to analyze humans and their behavior.

In astronomical research, to measure the speed of a celestial body, ten scientists may get ten different measurements. Which one is the true value is a big problem. But soon scientists found a simple and effective solution: to aggregate all the individual measurements from individual observations and get an average. Compared with the single observation results, this method can improve the accuracy of the observation results. Quetelent, who believes in this method, applies the same idea to human research, trying to find the average of human attributes, thus creating the concept of "average person" (Average Man). He believes that there is some kind of human prototype with average perfect attributes, and in reality each individual is a defective copy of this perfect prototype. In his view, the individual is equated with "mistake", and the "average person" represents the real perfect person [3].

The trend of the times also contributed to the flames, helping him to establish his own theory. Quetelet coincides with the first wave of "big data" era in human history, when countries begin to build huge bureaucratic management systems, count and publish a large number of data about their citizens, such as the number of births, the number of deaths per month, the number of crimes per year and so on. After returning to the Netherlands, Quetelet participated in a national census conducted by the Dutch government. During the survey, he obtained a large number of population-related data to unravel the mystery of "average human type": he calculated the average height, average weight, average skin color, average age of marriage, average age of human death, average birth rate, average education, and even average annual suicide rate. It's all about getting the average of human attributes.

Since 1831, Quetelet has carried out a series of cross-sectional study studies related to human growth. In 1832, he published an article entitled "Research on Human weight in different Age groups" (Research on the weight of man at different ages) in the Journal of the Academy of Sciences (Proceedings of the Academy of Sciences). In 1835, he compiled all his related research into a book and published three volumes of his masterpiece on the Development of Man and his abilities (A Treatise on Man and the development of his aptitudes). In Volume 2, Chapter 2, "Human weight Development and its relationship with height Development," he compared the height and weight of hundreds of men, women, children and babies in Europe, and obtained various records from hospitals, orphanages and even factories. Even 9-year-old child labor, the results show that, on average, the weight of people (people here are not specific individuals) should be proportional to the square of their height. This ratio is the Quetelet index (Quetelet's Index) that has affected the afterlife for more than a hundred years.

Figure 3. Quetelet is used to collect data on children's height and weight. Source: STAT is worth mentioning that the Quetelet index reflects the average human attribute pursued by Quetelet, that is, the "perfect state" of weight relative to height, and this index is only for statistical purposes. The calculation results obtained from large-scale measurement of population level data have nothing to do with individual body fat, body shape or health. Quetelet himself is even less interested in issues such as obesity. In addition, Quetelet's data sources are mainly French and Scottish, so the Quetelet index is designed for white Europeans, which is also an important limitation of the index.

Quetelet also wrote this paragraph in "on the Development of people and their abilities": "anything that is different from the proportion and conditions of the average person can be regarded as a deformity or a disease." if an individual in any social background has all the average attributes of the average person, then he is the representative of greatness, goodness and beauty. " [5] in the second half of the 19th century, Francis Galton, the famous father of eugenics, borrowed from Quetelet's concept of average person, but made an important change, which cast a shadow of racism on the Quetelet index (Adolphe Quetelet himself is not a racist scientist). Galton equates the average attribute proposed by Quetelet with a "mediocre attribute" rather than an ideal state, so it needs to be transcended, improved and overcome [6]. By the end of the 19th century and the beginning of the 20th century, eugenics in its heyday regarded the average person as a measure of parents' health, and the scientific basis for systematic sterilization of people with physical disabilities, mental disorders such as autism and schizophrenia, LGBTQ+ people, immigrants, poor whites, aborigines, people of color and ethnic minorities around the world. [7-9]

The "ideal index" weight of the insurance industry is one of the important health indicators, in fact, it has only become popular in the past century. The insurance industry, especially in the field of life insurance, has made a great contribution to the promotion of this concept. At the end of the 19th century and the beginning of the 20th century, life insurance companies in the United States began to pay attention to and investigate the risk of death related to weight measurements. They drew a comparison table of weight and height, imitating the research method of Quetelet index, in an attempt to associate weight with health and longevity, so as to evaluate policyholders and provide relevant guidance for insurance purchase and medical selection process [10].

At first, the comparison tables used by insurance companies were very problematic and could be said to be extremely unreliable. First of all, the weight and height data obtained by insurance companies come entirely from the self-measurement reports of life insurance customers in a specific period of time, and they are not random samples; secondly, there is no unified measurement standard for the data. some users wear shoes and thick clothes to measure height and weight, resulting in numerical deviation. Finally, the medical examination physicians of each insurance company have their own set of selection criteria, and the final evaluation forms vary widely from one company to another. However, in 1895, George Shepher, the medical director of the Connecticut Wantong Life Insurance Company, was commissioned by the American Association of Life Insurance Medical executives (ALIMDA) to analyze the data of more than 70, 000 policyholders from the United States and Canada for two years, and finally established a standardized height-weight control table, which was widely adopted in the industry.

One may ask: why should insurance companies make weight-height comparisons, rather than medical institutions?

Interest is a big driver. As a profit-making organization, insurance companies can obtain the highest profit by improving the medical choice process of future policyholders, so their enthusiasm is very high. In addition, at that time, the institutionalization of the American health care system was difficult, many aspects of the medical community could not reach a consensus, and the outside was faced with the problem of legality. As a result, the discourse power of standard-setting was ceded to the more mature insurance industry [8].

By the early 1940s, Metropolitan Life Insurance Company, the largest life insurer in the United States, combined medical experience with more accurate survey data to improve the weight-height comparison table, resulting in an "ideal weight" table that did not include age, and introduced a set of random and subjective body size categories: small, medium and large [11].

In this way, the ideal weight form used to be the selection criteria for the medical process, but now it has turned into an "ideal height-weight recommendation Guide" for the public, greatly deepening public awareness of the risk of obesity. Insurance companies set up welfare departments, carry out marketing, print brochures, strengthen people's desire for health and longevity, and mobilize public support for disease prevention and treatment. In addition, the insurance company's "ideal weight control table" has also appeared on the doctor's desk to quickly assess the relationship between a patient's weight and health, and set the tone of "what is a healthy weight." The whole trend peaked in the 1950s and 1960s.

Figure 4. Metropolitan Life Insurance developed the ideal height-weight comparison table from 1960s to 1980s. Source: obesitycare.com even today, the BMI index, which measures the degree of obesity, is still one of the reference standards for insurance companies when underwriting. People who are overweight tend to be in sub-health, and their health risks are higher than those of normal weight, which means they have a higher chance of getting insurance compensation. People who are overweight, such as severely obese, may have to pay a premium of 20% to 25% more to be insured. In addition, people with severe obesity such as heart disease, high blood pressure and diabetes may even be denied insurance [12].

"BMI Index" in the scientific research circle in the 1940s, the term "body mass index (index of bodily mass)" was first put forward in William Sheldon's book "Human physical Diversity" [10] (The Varieties of Human Physique). However, the calculation formula used by Sheldon is different from that of Quetelet. The ratio given by the former is the cubic power of height (meter) / weight (kg), namely h / w3.

However, the term "body mass index" (body mass index, abbreviated as BMI) first appeared in the scientific literature until 1959. A paper published in the journal Psychological report (Psychological Reports) [13] applied BMI to the somatotype of dogs, and the ratio formula was not related to the Quetelet index. The formula given by the authors is the cubic power of weight (kg) / height (m), namely w / h3.

Until 1972, Ancel Keys, an American doctor, picked up the legacy of Quetelet again, promoted the Quetelet index in the medical community, renamed it to BMI, and linked it with research related to body fat and obesity, creating the well-known "BMI index".

Figure 5. The cover of the January 1961 issue of time magazine, Ancel Keys, source: content.time.comAncel Keys was born in Colorado Springs, Colorado, USA in 1904, and his family moved to Berkeley, California, California as a teenager. His family is not rich. Besides going to school, Keys, a teenager, works everywhere to earn money: he has worked as a handyman in a lumbering yard, worked in a gold mine to transport dangerous gunpowder, and has been to a bat cave in Arizona to dig bat shit. In 1922, Keys was admitted to the University of California, Berkeley (UC Berkeley). During his first summer vacation, he went out to sea as a ship oiler and returned to school after three months at sea, but it took him only two years to complete his undergraduate studies. After graduation, Keys, who had continued to work, soon got tired of the boring and repetitive work every day, so he returned to his alma mater to study the biology subject he was interested in, and received his first doctorate in biology in 1930. [14]

Keys then flew to Copenhagen on a two-year scholarship to study with August Krogh, the Nobel laureate in physiology or medicine, and then to Cambridge to follow physiologist Joseph Barcroft, where he became interested in and studied how the human body adapts to extreme conditions. In 1936, Keys received his second doctorate in physiology.

Keys's early work and study experience has made him very clear about his future scientific research direction, and his scientific research career has also changed academic views on many aspects of human physiology and health, such as the effects of hunger on people's physiology and psychology, the influencing factors of coronary heart disease and so on. During World War II, his most famous scientific achievement was the invention of K-rations (K-ration), which solved the problem of food and clothing for front-line soldiers. [15]

After World War II, the American people no longer worry about not having enough to eat, but may eat a little too much, so heart disease has become the leading cause of death in the United States. To solve this problem, the government has poured a lot of money into scientific research, and people are beginning to realize that overweight and obesity, coupled with high blood pressure and high cholesterol, increase the risk of cardiovascular disease. Insurance companies, the American Public Health Service (Public Health) and the American Medical Association (American Medical Association) have teamed up to call on citizens across the country to take action to prevent overweight and obesity (figure 4).

By the 1950s, the famous "Seven Kingdoms study" (Seven Countries Study) conducted by the Keys team found two major healthy diets for later generations: the Mediterranean diet and the Japanese diet [16]. On the one hand, Keys acknowledges that obesity is a serious health hazard, but on the other hand, he disagrees with the insurance company's claim that obesity is the standard weight that exceeds height.

Figure 6. Cartoons that warned people to be overweight in the 1950s. Source: Youtube.com in the 1970s, the medical community worked hard for an effective and easy-to-use method of weight measurement, and Keys was also involved. In 1971, he and his team published a paper on "relative weight and obesity indicators" in the Journal of chronic Diseases (Journal of Chronic Diseases), which analyzed the height, weight and other related data of 7424 healthy men from five countries, and discussed the popular methods of measuring individual fat at that time.

There are a variety of methods, some using subcutaneous fat calipers to measure subcutaneous fat-body density, as well as the thickness of subcutaneous fat, and some weighing underwater to measure body density. In addition to these two popular measurements in the United States, there are the height / weight ratio used by insurance companies and the Quetelet index dug up by Keys from the old paper pile. In the end, Keys chose the Quetelet index as its first choice. "although the Quetelet index is not perfect, it does not underperform other relative body mass indexes and can be used as an indicator of relative obesity," he said, and the BMI calculation method is simple and fast and can be applied to all populations of all ages.

Quetelet was the first to calculate the w / H2 ratio, but he has never promoted it to the outside world. It is Keys's research that really promotes "BMI= w / H2" to the public as a general method for measuring body size or subcutaneous fat. In 1985, the National Institutes of Health (NIH) revised the definition of obesity [18] to associate it with BMI values of individual patients. Thirteen years later, NIH redefined "overweight" and "obesity" and lowered the medically recognized fat threshold, a move ridiculed by the US media as "making all Americans fat overnight without gaining weight".

One of the biggest advantages of BMI popularity is that it is easy to calculate: as long as any doctor has a BMI form in the office, no other tools are needed. The World Health Organization also recommends that the public can judge their weight according to BMI in order to maintain a good and healthy lifestyle [19]. Naturally, BMI has set off a new public health panic: the "obesity epidemic". At the turn of the millennium, the simple calculation of BMI index has become a necessary link when seeking medical advice, and it is also an important reference index for life insurance. Today, people with a BMI of more than 30 kg / m ²are considered obese, while those with a BMI of between 25 and 29.9 are considered overweight.

Figure 5. World Health Organization's BMI nutritional status classification table, source: World Health Organization (WHO) in addition to the physiological research field of overweight and obesity, in the medical field, BMI is also one of the most commonly used tools, especially in the study of the risk of various diseases, such as modern civilized disease prevention (disease prophylaxis) research, mainly related to cardiovascular disease, obesity and so on. Some studies use BMI values to determine obesity levels in developed countries in Europe and the United States, helping people realize that obesity trends are increasing and preventive measures are needed. Other studies have described the association between BMI values during adolescent development and stroke risk in adulthood, concluding that if young people's BMI increases every year, they will face a high risk of stroke in the future [20].

Another area where BMI is heavily used is diabetes. Studies have shown that high levels of BMI significantly affect the incidence of diabetes, and maintaining appropriate BMI can prevent the disease and curb the deterioration of the disease. Nutritional genomics (nutrigenomics) specializes in the effects of nutrients on gene expression and metabolic changes, and BMI is often used, mainly focusing on the relationship between gene polymorphism (gene polymorphism) and BMI, which are closely related to "rich diseases" such as Ⅱ diabetes and obesity [20].

Limitations, questions and Countermeasures

With the development of science, we gradually realize the complexity of the human body. In recent years, researchers have begun to question whether the calculation of BMI is so simple that it can really be used in increasingly complex research.

One of the limitations most criticized by experts is that BMI cannot clearly tell whether the overweight comes from muscle, fat, or bone. It is well known that muscle density is higher than fat, and people with the same height but high muscle tissue density are heavier. According to the BMI calculation, it is easy to classify this person as obese. As early as 2004, a paper published in the Journal of Contemporary Sports Medicine (Current Sports Medicine Reports) focused on athletes and pointed out the tendency of BMI to misclassify athletes [21]. An athlete's weight is often affected by his sports, degree of exercise, and eating habits. Take basketball players as an example. Their BMI is between 21.4 and 26.7. Only looking at BMI, some people may be overweight, but their average body fat rate is only 10.7%. The overweight is muscle mass, not fat mass, which means that BMI cannot measure body fat rate.

Francisco Lopez-Jimenez, director of Miaoyou Medical International Preventive Cardiology (Division of Preventive Cardiology Mayo Clinic), whose research focuses on obesity and cardiovascular disease, has a clear opposition to BMI: "We are too dependent on BMI in most cases. In terms of population, BMI seems to perform well, but at the individual level, the effect is not good. For example, someone with a BMI of 28 may be healthier in many ways than a person with a BMI of 25, because the former may exercise every day and have a lot of muscle mass. " [22]

Second, fat stored in different parts of the body has different effects on disease risk assessment, while BMI cannot indicate the distribution of body fat. In 2015, the Lopez-Jimene team published an article in the Annals of Internal Medicine (Annals of Internal Medicines) [23], suggesting that both men and women with normal BMI (22 kg / m ²) but concentric obesity (central obesity, meaning fat is mainly stored around the waist) face a higher risk of death than the control group with the same BMI but non-concentric obesity.

In addition, BMI does not reflect the disease risk of different populations. As mentioned earlier, the data source of Quetelet is limited to white Europeans, and the subsequent analysis of Keys is mainly based on Europeans and Americans, and other groups only consider Japanese, so the object of BMI is more biased towards Europeans and Americans. A paper published in 2009 in the Yearbook of Singapore Medical College (Annals Academy of Medicine Singapore) pointed out that the BMI cut-point value (cut-off points, that is, the threshold between normal, overweight and obesity) for Asians is lower than the international BMI cut-off value recommended by the World Health Organization [24]. A 2018 study by the Harvard Medical School team also revealed that men and women of different ethnic groups have different BMI tangent points [25], for example, healthy black women have higher BMI values than the international uniform BMI standard; when measuring diabetes risk, black women's BMI is closer to 33, while white women's average BMI is 29. Therefore, the article opposes the one-size-fits-all evaluation model of BMI and calls for the calibration of BMI based on biological methods to evaluate the degree of obesity more flexibly and humanized. [26]

To sum up, the simple and easy calculation of BMI value not only gives it 200 years of vitality, across different industries, but also becomes its deficiency, which makes it difficult to adapt to the increasingly sophisticated scientific research and health management. Today, in addition to the BMI value, we can choose more accurate ways to measure body fat according to different needs, using other "health indicators" [27].

The simplest and most economical detection method is skinfold fat test (skin fold test). Professional doctors use non-invasive sebaceous calipers (body fat caliper) to measure the sebum thickness of the back, arms and other parts of the body, and compare body fat assessment criteria (mainly for young to middle-aged people), the results are accurate and help to judge the level of health. In the healthiest state, the body fat mass should be 20% to 30% of the body weight for women and 12% to 20% for men.

Bioelectrical impedance analysis (Bioelectric Impedance Analysis) is also a commonly used method of measurement, the principle is to let a small amount of current through the human body, measure the current speed to determine the composition of the body. At present, there are already household intelligent electronic scales (body composition scales) on the market, which can be connected to mobile devices such as mobile phones and tablets to monitor and record your body data at any time.

Another measurement with higher professional and technical requirements and higher accuracy is the dual-energy X-ray absorptiometry (Dual-energy X-ray absorptiometry,DEXA), which can not only monitor the body fat content, but also check the "hidden" visceral adipose tissue volume, which is an important reference index for disease prevention and treatment. This equipment is usually available in hospitals.

In addition to directly measuring fat content, we can also evaluate our own situation from the distribution of fat. Fat accumulates in different parts of the body and has different effects. Measuring waist circumference (waist circumference) measures abdominal fat content, which is hidden deep in the body and stored around vital organs, increasing the risk of obesity-related diseases such as Ⅱ diabetes, high blood pressure and coronary artery disease, which is much more harmful than subcutaneous fat [28].

Besides waist circumference, waist-to-hip ratio (WHR, waist / hip circumference) is also of great reference value. According to World Health Organization (WHO) 's standard, the best healthy waist-to-hip ratio is ≤ 0.85 for women and 0.90 for men. In addition, a 2005 study published in the Lancet analyzed data from 27000 subjects from 52 countries and found that waist-to-hip ratio was closely related to heart attack and was better than BMI in predicting the incidence of the disease. [30]

Finally, if you want to check your physical condition from the perspective of disease surveillance or prevention, indicators such as waist-to-hip ratio, blood sugar, triglycerides, blood pressure, cholesterol and heart rate are the "windows" that can better reflect your health. Because these indicators are more closely related to heart disease, diabetes, stroke and other diseases [31].

Although there are many criticisms of BMI in academic circles, BMI is still widely used and will not disappear overnight. Understanding the complex history of BMI, we may instead regard it as the "starting point" for us to attach importance to our own health, rather than the only "gold standard", broaden the more dimensions of health management and benefit from different health indicators.

reference

[1] https://www.who.int/news-room/fact-sheets/detail/obesity-and-overweight

[2] https://www.prnewswire.com/news-releases/countrys-leading-obesity-care-organizations-develop-consensus-statement-on-obesity-301734250.html

[3] https://www.theatlantic.com/business/archive/2016/02/the-invention-of-the-normal-person/463365/

[4] Quetelet, Ad.. "Recherches sur le poids de l'homme aux diffé rens â ges.." Nouveaux m é moires de l'Acad é mie Royale des Sciences et Belles-Lettres de Bruxelles 7 (1832)

[5] Quetelet A., A Treatise on Man and the Development of his Faculties. Originally published in 1842. Reprinted in 1968 by. Burt Franklin, New York

[6] http://eugenicsarchive.ca/discover/connections/5233cb0f5c2ec5000000009c

[7] https://elemental.medium.com/the-bizarre-and-racist-history-of-the-bmi-7d8dc2aa33bb

[8] https://www.genome.gov/about-genomics/fact-sheets/Eugenics-and-Scientific-Racism

[9] https://ihpi.umich.edu/news/forced-sterilization-policies-us-targeted-minorities-and-those-disabilities-and-lasted-21st

[10] https://journals.sagepub.com/doi/pdf/10.1177/1536504217732057

[11] https://www.psychologytoday.com/us/blog/the-gravity-weight/201603/adolphe-quetelet-and-the-evolution-body-mass-index-bmi

[12] http://www.cntaiping.com/service/78277.html

[13] https://journals.sagepub.com/doi/abs/10.2466/pr0.1959.5.h.495

[14] https://www.mayoclinicproceedings.org/article/S0025-6196(19)31088-2/fulltext

[15] https://www.nytimes.com/2004/11/23/obituaries/dr-ancel-keys-100-promoter-of-mediterranean-diet-dies.html

[16] https://www.sevencountriesstudy.com/about-the-study/

[17] https://academic.oup.com/ije/article/43/3/655/2949547?login=false

[18] https://academic.oup.com/ije/article/43/3/655/2949547?login=false

[19] https://www.who.int/europe/news-room/fact-sheets/item/a-healthy-lifestyle---who-recommendations

[20] https://biomedgrid.com/fulltext/volume4/influence-significance-and-importance-of-body-mass-index-in-scientific-research-and-various-fields-of-science.000816.php

[21] https://journals.lww.com/acsm-csmr/Abstract/2004/08000/Overweight_Athlete__Fact_or_Fiction_.5.aspx

[22] https://www.statnews.com/2023/03/09/bmi-body-mass-index-troubled-history/

[23] https://www.acpjournals.org/doi/10.7326/M14-2525?articleid=2468805

[24] https://annals.edu.sg/pdf/38VolNo1Jan2009/V38N1p66.pdf

[25] https://www.mayoclinicproceedings.org/article/S0025-6196(18)30807-3/fulltext#%20

[26] https://www.insider.com/guides/health/is-bmi-accurate

[27] https://pressbooks-dev.oer.hawaii.edu/humannutrition/chapter/indicators-of-health-body-mass-index-body-fat-content-and-fat-distribution/

[28] https://www.nytimes.com/2021/05/18/style/is-bmi-a-scam.html

[29] https://www.who.int/publications/i/item/9789241501491

[30] https://www.sciencedirect.com/science/article/abs/pii/S0140673605676635

[31] https://health.clevelandclinic.org/is-bmi-accurate/

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