I hate that we still use BMI. I was maybe 10 years old when I learned that BMI as a reliable indicator of health was a total myth. My siblings and I would often play Wii Fit, where there was a weight measurement feature. We’d put in our height, age, sex and then they’d determine our health. Mine would always say “At risk of overweight”. I was 5 feet tall (I still am) and around 127 pounds. My mom would reassure me that it was mostly muscle and that I was perfectly healthy. But when I’d go to the doctor, they’d print my BMI on the reports and my status as “almost overweight”.
So eventually I researched the origins of the Body Mass Index and learned that the data actually came from average weights in 17th century Europe from a mathematician, not a doctor. I thought, “Okay, this makes sense since this scale doesn’t seem to take into account my body type as a Hispanic woman”. Now there is a general consensus that BMI is outdated but people still use it, and it’s harmful. If I didn’t have the reassurance of my mom, I’d be convinced I was overweight. That, in combination with the unhealthy influences that tumblr imposed on me as a pre-teen, I would have engaged in even worse behavior towards my body.
While I love statistics as a math major, I started to feel gross that these numbers would weigh over people’s heads the way it weighed over mine. There’s an assumption that numbers can’t lie or that they’re unbiased, but there’s a plethora of ways numbers can be misused. From the origins of modern statistics ー whose progenitors were eugenicists in the 1910s-1930s ー to today’s incels who use “statistics” to justify their hatred toward women. The way data is collected, measured, and interpreted can all be extremely biased. Not everyone takes courses in statistics that demonstrate just how much data can be manipulated to achieve an agenda. No amount of measurements of skull shape, muscle mass, penis size, weight, and height can justify recommending/enforcing entire groups of people do not reproduce.
I feel like many STEM and even some social science majors can relate to the concept of their field of study being used to justify discriminatory policy through medicalization. It’s something I knew I’d have to consider and navigate once I entered the workforce. My older sister is in medical school and thankfully their curriculum attempts to dispel myths on certain statistics about women and people of color. But there is still a lot of medical professionals who believe in these numbers as inarguable fact, and they have quite a bit of influence.
I’m not saying statistics is obsolete or unimportant. I still love numbers and I think collecting data is useful, but I think there should be a more holistic approach in analyzing our own bodies.
Unruly Bodies 
I can really relate to your experience. I remember in middle school I’d obsess over my weight just because my doctor would tell me that my BMI was nearing overweight and then avidly being a tumblr user where skinny girls and thigh gaps were glorified. Plus being a Korean girl growing up where comments about your weight are constant and normalized, it definitely had me dysmorphic and unsure of what I really looked like. Looking back I was on the thin side too but my experiences and memories tell me a completely different story. I also definitely agree that the U.S./the West has a tendency to just casually justify eugenics. Even me being a Psychology major, I see how people will create studies basing eating/weight/genetics based on race and not even realizing how it’s veering into justifying eugenics. I think you bring up an important point that no matter what field you go into, you have to be knowledgeable and aware of things like this.
I remember when I read the article for class that mentioned eugenics and it was all new information to me! I have taken statistics courses but I never really heard about the history of stats. As an engineering major, I would have assumed that with so much talk around ethics, I would have learned more about eugenics. I knew the BMI was harmful, but I never saw it as untrustworthy. Growing up, I never thought much about it and never knew about it’s creation until I started college. I was always labeled as “obese” but never felt like that represented how I felt I looked in my body. I wonder how the system would be different if a doctor created the BMI. I bet it would only be slightly different depending on when it was created. Even know there are many discriminatory practices in medicine, so having a well rounded sample size would probably not have been a priority to even a doctor making the BMI. This goes into your argument of how numbers are easily biased. That should be explained more so that way people can try to have more autonomy over their body in a society that wants to label it for us.