A number of years ago, I realized my sons were taller than I was. I asked if they'd been growing (in their 30s!), but it turned out I had begun shrinking. And so, as a lark, I started a "Shrink Chart" on a door jamb to measure how much I shrink. The top line in the photo was my height about 7-8 years ago, the bottom line was today. The difference between the top line and the bottom line is about two inches, and that's after I had already begun shrinking.
Even though I've lost some weight, my BMI went up!
[note: yes, I take meds and supplements to strengthen my bones, and yes I do back exercises too (probably not enough).]