19: BMI History, Flaws, and Better Measures of Overall Health with Dr. Kara Pepper

Jun 26, 2023

Thinness equals health. There are generations of doctors that have been trained to believe this, and we have been indoctrinated by this concept for so long that it’s hard to believe anything else. One of the biggest contributing factors to this is the widespread adoption of the Body Mass Index (BMI) as a measure of health by the medical system.

So where exactly does the BMI originate from and should we still be using it as a tool to assess someone’s health? Today I want to explore why the BMI is fraught with misinterpretation, and what we should be looking at instead. We also look into how patients who struggle with eating disorders can be better supported in a clinical setting.

The origin of BMI

When you look back at Renaissance paintings, you see a lot of full figured people. Fatness was used as a neutral term, not a derogatory term, and was synonymous with health and wealth. Having a larger body was considered ideal at that time. 

As Colonization started to take over the world, we began to see the othering of people of color who had more curvaceous or larger bodies than the malnourished working class white folks of Europe. It became a way to say that thin white is the ideal moral standard, and blackness and fuller figures is not.

In the 1800s, there was an astronomer by the name of Adophe Quetelet, who was not in healthcare, but wanted to find a way to measure what the “normal body” would look like. And so he came up with what we now know as the BMI, which is essentially a height and weight comparison. However, it’s important to note that he was using only French and Scottish men at the time. These were people with poor food supply who were white males, laboring in the 1830s. His work then became the basis for how to measure the size of someone's body and use that against them and to say they are not worthy. 

It wasn't until about a hundred years later in the insurance industry in America, when people started to say, ‘how can we make money from life expectancy?’. So they started looking at small, medium, and large size frames and the idea that people of different sized bodies might live different life expectancies got into our culture.

In 1972, Ancel Keys was the one who solidified the BMI in medicine. They began looking at the ways to measure fatness or adiposity, such as body density (submerging someone in water and measuring their fat by that capacity), BMI, and fat calipers (pinching fat and measuring it manually). Of those three metrics, the BMI was the best of the worst, meaning only about 60% of the time did it accurately measure adiposity. 

The cohort that he used was again only male, and they were from Italy, the United States, Finland, Japan, and South Africa. The Black men from South Africa skewed the data, so he took them out and just continued to use white and Asian men. The NIH started using the BMI as a measurement of obesity in the 1980s, and said the cutoff for overweight was 27.5 - 30, and obesity was measured with a BMI greater than 30. In 1995, the WHO Expert Committee started adopting that, and so it infiltrated our medical system and our research trials.

In the late 1990s, The International Obesity Task Force, whose two principal funders were companies making weight loss drugs at the time (Fen-Phen and Redux), changed the BMI cutoff from overweight at 27.5 to 25. Therefore, overnight, millions of Americans suddenly qualified for these drugs. It was absolutely clear that these guidelines were set in place to make more money. 

When we've looked at the BMI specifically in marginalized populations, it overestimates in people of color and underestimates it in Asian populations. It does not correlate for women and across age spectrum. It is fraught with misinterpretation, but at this point it is baked into everything that we do and there are two generations of doctors now who are trained that thinness equals health. 

“The take home is that the BMI is not a great metric for what we're looking at.”

Better measures of overall health

So often as physicians we hear “I want to be thinner so I can be healthy”. But what do we really mean by “healthy”?

When you dig in deeper, you get to the real desires like being able to play on the floor with grandkids without pain, or being able to sleep through the night, or to feel connected with people you care about. All of those have absolutely nothing to do with the size of one's body.

Prioritizing the patient and their unique values is the primary goal of care. Then you can start figuring out all the ways to go about doing that. 

Physicians, clinicians, and patients need to all start asking: If you could not change the size of my body, what would you recommend if we’re not looking at thinness as a metric? 

We will quite happily say, “oh, you’re allergic to this medicine, let me figure out another option for you”, and so weight is no different. You can achieve those goals without inducing restrictive eating behavior.

Screening for eating disorders

The use of BMI can also exacerbate mental health concerns such as eating disorders. It’s therefore important for clinicians and patients to be conscious of appropriate screening taking place.

For clinicians, it’s vital to assume that every patient has an eating disorder. They thrive in shame and secrecy, so patients are unlikely to show up and say, “Hey, I have an eating disorder”.

We're all indoctrinated with diet culture and the behaviors are very subtle, so we may think they're normal. For example, not eating for 16 hours of the day because you’re doing intermittent fasting is actually a restrictive eating disorder behavior. Being so rigid with the gym and a keto diet that you can't go out to eat with your friends and family, would also fall on the spectrum of eating disorder behavior. 

Asking about specific behaviors is therefore crucial to effectively screen patients. For example, you could ask:

  • Tell me how you ate yesterday. How did you fuel your body? 
  • What is your relationship with food, diet, exercise, and your body?
  • Do you have a persistent desire to be thin? 
  • Does it make you nervous to think about gaining weight? 
  • Do you ever purge to get rid of food that you've already eaten? 
  • Do you ever over-exercise in anticipation of, or a result of what you've eaten? 
  • Do you have trouble with certain sensory textures of foods?
  • Do you ever avoid foods because you don't like the way that they feel? 

For patients, there are a number of resources out there to help you find an eating disorder professional, with lists of dieticians, therapists and clinicians who are Health at Every Size certified or who are engaging with that. Finding someone in your community will make a huge difference and telemedicine has really opened the doors by not having to live in the same city as that provider anymore.  

And if you are someone that is struggling with an eating disorder, please reach out to your medical team for help, or contact the National Eating Disorder Help Line for further advice.

More about Dr. Kara Pepper:

Dr. Kara Pepper is a practicing primary care Internist and Certified Life Coach in Atlanta, GA. After 14 years in private practice, Dr. Pepper built her own solo telemedicine practice for adults across the southeast, especially those with eating disorders.  She is also a coach for exhausted perfectionists through career change, burnout, and impostorism. She provides one on one and group coaching, leads retreats, and speaks on topics surrounding clinical wellness.  

Connect with Dr. Pepper:

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