I had this once. I've never forgotten it. I have PCOS, and in my teens, suddenly ballooned with a combination of the onset of the condition, and side effects of the contraceptive implant (which I never wanted but was heavily pressured into by a parent). I had tried to explain to the nurse I had gained a lot of weight quickly, after having the implant fitted, and had no lifestyle or eating habits change. At all.
The nurse refused to believe it (funnily enough, when the implant ran its course, I dropped 5 stone very quickly, again without any change of eating habits or lifestyle changes).
When she told me she was going to weigh me, I told her I was ok with her recording it, but I did NOT want to be told what it was, as it would effect my mental health as I was feeling terrible about all of this, and explained to her I was well aware of my size and that I was an unhealthy weight.
She took my weight. Out loud. Just spoke it out whilst reading my weight. I was at this point, already struggling with having gained such a large amount of weight so quickly, and having intrusive thoughts about 'dieting' (and visiting pro-ana websites obsessively). I stopped eating completely for weeks after this, and my only income of calories was from some fizzy drinks (I had done a couple of much shorter stints prior to this). I obviously dropped a good amount of weight, but I ended up very unwell. Not as unwell as someone who wasn't obese when they started would be, thankfully.
Unfortunately, obviously, as soon as I started eating again, I gained it all back plus more. And my body was fucked from it. It took a good couple of years to get the binge eating and starving cycles under control, along with my mental health. Mind back then, help for people who had starve/binge cycles but were obese was not a common thing, my family tried.
The nurse didn't cause my ED, but she certainly did not fucking help, and triggered a massive downhill spiral. As I say, after getting things under control over the next couple of years, and returning to my usual diet, when the implant ran its course, I dropped the weight with no effort (or even attempt) at all.
The nurse took advantage of a young girl/teenager, and abused her position in my case and yours OP. Contrary to what many people believe, fat people are well aware they're fat and not in denial. They see themselves in the mirror every day. A nurse doesn't need to confirm it for them by reading a weight out. They can confirm it in other ways, in a supportive and helpful manner, offering solutions and listening to the patient.
Please complain, if you feel able, OP. The next time it might be another vulnerable young girl who doesn't realise they can complain about this or doesn't feel like she has a say. It's bad enough it happened to you. And I hope the nurse who saw me about 15 years ago ish is reading this. You're a horrible cunt.