August Newsletter

If you’ve had a medical visit within the last 50 years or like to read health related topics, my guess is you are somewhat familiar with body mass index (BMI). It’s the weight-to-height ratio used by healthcare providers, insurance companies and the scientific community that places you into a weight category.  What you may not be familiar with however is the growing amount of criticism around this number. Intended to be used as a measurement among large populations, it has become a standard of health. 


A Little History Lesson

The BMI, originally named the “Quetelet Index,” was devised in the 1830s by Lambert Adolphe Jacques Quetelet, a Belgian astronomer, mathematician, statistician and sociologist. Remembering that the calculator was not yet developed, he used a simple system based on two factors, height and weight. His selected sample size consisted of an exclusively white, European population thought to be primarily Scottish and English males in their 20’s. Women of childbearing age or menopause were not represented. Neither were adolescents going through growth spurts.

Variables and allowances for body shape and size, waist circumference, bone density, muscle and fat mass, race, and ethnicity were not taken into consideration. For reference, bone is more dense than muscle and twice as dense as fat, so a person with strong bones, good muscle tone and low fat will have a high BMI. 

The purpose of the formula was to observe “norms” in the general population as determined by a bell curve for research purposes in order to assist the government in allocating resources. It was never intended to be used as a measure of health or body composition for individual evaluation. 

Once physicians began to weigh people as standard practice, in the 1940-1950’s, the Metropolitan Life Insurance Company started compiling data to determine charges for their customers. Eventually weight ranges, that hinge on the placement of a decimal point, were defined. Distinct categories of “underweight,” “ideal,” “overweight” and “obese” were created only to be changed literally overnight in 1998 when a panel of specialists were brought together and altered the categories. 

I remember waking up to this morning news then discussing the ramifications at work amongst fellow healthcare practioners as the decision by the NIH lowered cut-offs for the “overweight” and “obese” categories. This decision made millions of people “overweight” instead of “ideal” and “obese” instead of “overweight” without gaining an ounce. (Blackburn H, Jacobs D, Jr. 2014). 

Researchers now know that these changes were based on a report from the World Health Organization (WHO), written by the International Obesity Task Force (IOTF) and funded by a couple pharmaceutical companies that make weight loss drugs… an example of how the $72B diet industry infiltrates our health care organization.

How Is It Viewed Now

According to the Centers for Disease Control and Prevention (CDC), “BMI is not a diagnostic tool;” and using BMI as a predictor of health is limiting, as “weight is only one factor related to risk for disease.” In fact the probability of an “obese” person of either sex attaining “normal” body weight is less than 1%. (Fildes et al 2015). 

Weight is not a behavior; nor is it a reliable proxy for health or fitness. It is a data point. Research shows that focusing on modifying behaviors that promote a healthy lifestyle in a weight-neutral way is more effective then attempting to modify weight. In fact diets are the biggest indicator of weight gain. We know that now. Interventions should focus on providing opportunities for appropriate levels of physical activity and healthful eating, while also promoting self-esteem, body satisfaction, and respect for body size and shape diversity.

The bottom line is BMI should never have been used as a proxy for health. Interestingly, modern data with more diverse samples show that people who fall in the “overweight” category have the lowest mortality risk of any group in the BMI chart, misclassifying people as metabolically unhealthy.


In fact, for shock value, >50% of people who are >25 BMI are metabolically healthy (that’s 1 in 2 people!); 30% of people >30 BMI are metabolically healthy; 16% of people who are >35 BMI are metabolically healthy and 25-30% of those with a “normal” BMI of 18.5-24.9 are metabolically challenged/unwell/diseased. (Tartakovsky M 2010).

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Blackburn H, Jacobs D, Jr. Origin and evolution of body mass index (BMI): continuing saga. Int J of Epidemiol. 2014;43(3):665-669. Commentary: Origins and evolution of body mass index (BMI): continuing saga

Fildes et al. Probability of an Obese Person Attaining Normal Body Weight: Cohort Study Using Electronic Health Records. AM J Pub Health. 2015.Sep;105(9):e54-9. 
https://pubmed.ncbi.nlm.nih.gov/26180980/

Tartakovsky, M. More on Health At Every Size, Diabetes & BMI: Q&A with Jon Robison, Part Two.Psych Central. (2010). Retrieved from http://blogs.psychcentral.com/weightless/2010/03/more-on-health-at-every-size-diabetes-bmi-qa-with-jon-robison-part-two/

https://blogs.psychcentral.com/weightless/2010/03/more-on-health-at-every-size-diabetes-bmi-qa-with-jon-robison-part-two/