BMI. I don't get it.

[AudaCityLimits]

OK so I've not been well since lockdown. Got an appt with the doctor today, several tests etc. She weighed me and I was 55kg. I'm 5"11. Which makes me underweight according to BMI- it works out 16.9.
I'm a size 12/14.
I am in shock. I have an ED but am well at the moment, eating meals and not obsessing about food. But I thought that I'd be clued up on weight/height/bmi because I have obsessed about it before. I don't have scales in my home because of the aforementioned ED, but afaik I have never been so light before. And yet, my clothes aren't hanging off me...
Size 14 and underweight? Anyone had this before?

I cannot comment on your eating disorder because that is something I simply have no knowledge of. However...

I am 5'10" and around 77kg, with a frame on the border of medium/large. I currently wear size 12/14 clothing. There is no way that 55kg is correct if you wear the same size as me (see pic).

Just be mindful that you don't become fixated on your weight if you buy scales. Weight is just a number and is affected by many things: alcohol intake, sodium, etc can make it jump up overnight. And your muscle mass/body fat balance will also affect the number on your scales. Muscular people with little body fat tend to look slimmer, but the muscle density makes them the same weight as their skinny fat former selves.

So many things to consider.

for you.

I’m 5’11 and weigh 10stone 8lb. I’m a size 10.

I was a 12-14 when I weighed 12 stone 8 last year.

A person with a slender frame well coated in muscle will need the same size clothes as a person with a wider frame but very low muscle. So you may wear a bigger size because of your frame, but still not have enough muscle where you need it.

If you have a wide frame, big hands and feet, then you need to weigh much more than a person with a more slender build.

I'm built wide, like you, though not as tall. I can fluctuate hugely in weight but still say the same dress size. I lost 2 and a half stone, and didn't get to buy any new clothes! The places my weight sits are not the places clothes fit me.