Why Do We Use the BMI? History of the Body Mass Index

The history of the BMI is… troubled, to say the least. As a health metric, it doesn’t really tell your doctor much information that they couldn’t get in other ways. So why is it still so popular?

☠️NONE OF THE INFORMATION IN THIS VIDEO SHOULD BE USED AS MEDICAL ADVICE OR OPINION. IT IS FOR GENERAL EDUCATION AND ENTERTAINMENT☠️

🔗 L I N K S 🔗

📜 S O U R C E S 📜
A line-by-line, fact checked version of the script can be found here. You do not have to be a Patron to view:

💻 C O N T A C T 💻
If you’d like to sponsor a video or have other business inquiries:

#historyofmedicine #medicalhistory

[beatrice.pineapple]

As a nursing student, they made us calculate our own BMI and a few people in my class - including myself - fell in the overweight or even obese categories depsite being perfectly healthy, some from bodybuilding and muscle mass, others pretty much just for being black. When we asked our teacher why we still had to learn such an innacurate mesure of health her answer was "because doctors will'... Hopefully doctors can figure out a better way to mesure health on an individual level sooner than later. Thanks for this great video, super informative!!

[johnmichaelrichards]

The other issue with BMIs is that they were more geared to male rather than female physiology from the outset onwards and so are not as good a health predictor for females.

[mariekatherine]

The one time my BMI was in the “correct” range, I’d gone on a crash diet to fit into a dress for my friend’s wedding. I was underweight, had low BP, crashed potassium and iron levels, heartburn, and didn’t get my menstrual period for six months. The doctor put me on a gradual weight gain diet and I opted to let my cycle return naturally rather than take hormones. I gained thirty pounds and everything returned to normal including my nearly “obese” BMI.

[natalie]

Is anyone else concerned that they didn't even include women in any of these measurements??? Like I'm supposed to weight the same as an average white man in the 19th century?? That doesn't make any sense

[hamzaasif]

As a physician I can tell you that we know BMI by itself is not a good indicator for health. Like anything (including lab results etc) by itself it doesn't mean anything. If someone comes with a low/high BMI the only thing is to figure out if there's anything else wrong and rule those things out. The biggest advantage to it and why we still use it today is because it's free, fast, and easy to calculate. It gives you a snapshot of a person's weight related to their height. Manage of a 30 BMI bodybuilder isn't the same as a 30 BMI pt w/ DM or a 30 BMI pt w/o any comorbids. Think of it as something with high sensitivity but low specificity. Sorry for rambling but I hope you understand what I'm trying to say. Stumbled onto you from Knowing Better. If you don't listen to it already I highly suggest the Bedside Rounds podcast!

[SIC]

Many surgeons/hospitals require a very specific BMI for treatments. *Not* a good way of using BMI.
A friend of mine needed breast reduction surgery, and was forced to get a BMI below 25.
She was an average size M, but she lifted weights and her BMI was 27.
She had to stop lifting(!) and also go on a strict diet, to be able to get to 24, 9 and have the surgery.
She was furious, but had no other option than to play along, in order to get the surgery paid for.

Afterwards she had her body composition checked at her gym, and her muscle mass has decreased, while her fat mass was higher than it was before she lost the weight. 😑😖

* If people are very obese, surgery can have added risks.
But here we are talking about using BMI
1. As the only metric, not looking at anything else she l about people's bodies and health
2. with a sharp cutoff at the arbitrary 25.

[Rosie-ytnd]

BMI is still used in pharmacology today. As medications are often calculated by weight, in people with high body fat this can lead to toxicity. As these people are underrepresented in clinical studies and there is a lack of study of how to best accurately dose such individuals, the BMI (or only slightly modified version) is often used to make those adjustments, which is inadequate. We owe it to people to do better. To question all our accumulated data for bias and do research into people that have been historically excluded and overlooked

[mg]

One other problem of using BMI at an individual level - it assumes everyone's extra weight comes from fat. A bodybuilder could be classified as obese according to BMI. I have seen people lose weight while getting a belly - they were losing muscle and putting on fat. According to their BMI their health was improving.

[FakeSchrodingersCat]

The other problem is that the calculations for BMI quickly breaks down for taller people. It was created using a limited sample size both in terms of race but also in terms of height variation and it did not properly take that into account either. You will be hard pressed to find a person over around 6' that is not at least overweight according to BMI, even if physiologically they are underweight. And since the average height of people has increased so much over the past hundred years that has only made the statistical situation worse.

Back in high school I was just under the obese range of BMI but you could see my ribs. When I moved to college and changed doctors, before the first appointment based on the forms I had to fill out, he emailed me and recommended I get more exercise and loose weight, after meeting me he recommended I eat more. He still recommended more exercise.

[hedgehog]

Kinda reminds me of how IQ isn't really so much meant to be a way to determine whether individuals are smart but is more so meant to find outliers among a population to better shape education for their needs. IQ is specifically designed so that 100 will be the average with the original idea being that anyone who scores significantly above or below will have different educational needs, someone who scores below might need more help to catch up but someone who scores above probably also needs more attention in the form of more challenges. But then people started interpreting on an individual level and a ton of moralistic and racist ideas about intelligence got mixed up with it.

[정승기-hd]

I've got the opposite problem. I'm a white guy living in South Korea. My BMI is about 22. I've got 10% body fat. Every year when I get my health check, I'm listed as Obese because of my BMI. It's insane.

[viabell]

I went to a new doctor, who told me I was morbidly obese. I wear a size 10 (women's) and swim competitively. Definitely not obese.

[skeptiwolf]

There is also body shape for women. Thick thighs save lives. If you carry your weight on the lover part of your body it reduces the risk relative to other body shapes.

[highstepnightowl]

I was gifted a large frame (elbow&wrist ratios, jewelry shopping is a nightmare) and non-dystrophic myotonia. BMI is just cruel for the women in my family. I've only graced the high end of the normal range once, for about 3 months. My ribs were showing through the front of my sports bra and I got bruises on my arms from hitting my own hip bones.
My main concern is proper dosage of medication and anesthetics. Dentists usually have to stop partway through fillings to do a second round of injections for me. I try to hold out through the pain but they usually notice me crying or digging my nails into the chair.

[AwakeAtTheWheel]

BMI as a measure of body fat screwed my chances of promotion in the Army, even though I maintained my post basic training weight. Small neck. 🙄

[erinmckibbin]

If doctors know bmi is inaccurate, why do they deny me testi g, diagnosis, and treatment of unrelated conditions because of my bmi?

[goosie]

One of the first things we learned about BMI doing post grad sports science is that it’s not a good health indicator but it can be used for performance comparisons like with oxygen usage maximum. Also I was classified as underweight for a long time, the whole of my time playing high level sports, I’m now a “healthy weight” and am 5kg over what I played at an am significantly less fit and strong than I was then.

[stephanieparker]

My doctor doesn’t even discuss or reference the BMI index. She collects information from me specifically and makes recommendations based on that data.

[jamesoliver]

BMI is still used because it's baked into the "best standard practice" of the medical industry and individual doctors will be crucified by stepping out of those bounds. My physician was essentially threatened by our state licensing board. We have learned to speak in a sort of code, a mash of what he can, and cannot, , actually say, and me explaining to him what I know of the chemistry involved and what I plan on doing, and him either openly agreeing or standing mute.

[lourias]

I know that I am "big-boned" because:
1. At 5 '6", and 141#, I look horribly underweight, every bone in my body sticks out as though I am starving.
2. My wrists are larger than the average man's wrist. My 6'3" husband's wrists are much smaller than mine.
3. I have feet which are best measured in Men's sized, and still have larger than a 6E width.
4. My mother was the shortest of all her siblings, standing at 6'0". My wrist was larger than hers.

According to those charts, I should be 137#. Nope, I tell you, I look deathly immatiated at 141#.