>>106551885People still use BMI to estimate body fat content because the alternatives suck ass. The most accurate methods include: a pod that measures air displacement, radiology scanning (DEXA), and putting current through you to measure the impedance--all of these require equipment, are relatively expensive, and are inconvenient to measure. BMI is good enough for ordinary clinical use because when you walk through the front door, the nurse/doctor can sure as hell recognize the difference between 30 BMI of fat vs 30 BMI of muscle, and if that person is the former, it sets a quantifiable threshold to start considering a conversation about weight loss. So it's dumb as hell to say BMI is a perfect tool for health, but it's equally dumb to say BMI is completely useless.
Iirc, in the 1900s, the US military used a set of 7-ish circumference measurements to determine body fat/health. The modernized version has cut out some of the less useful measurements, and I found the idea pretty neat.
I've also read there's a push in medicine to use define obesity using abdominal circumference instead of height & weight, although I'm not sure how true it is irl. Iirc, for men, abdominal obesity is defined as >40in (>35 if asian male). For women, it's >35in (>32 if asian female)