I was 'underweight' according to guidelines. I didn't have physical or mental health problems, I just had a very physical job at the time.
I'm not pretending that being underweight is the same as being thin, I'm saying that you simply can't tell from looking at the number on the scales that someone is starving their body/deficient in nutrients, etc. All we have to go on from the OP is a number on the scales. Nothing about lifestyle, eating habits, fitness routine.
I wouldn't assume from a post simply stating someone's weight and height that they had an eating disorder, or lacked nutrients, or were going to be diabetic, etc, because I know nothing about them. I was responding to a post which stated that people were falling over themselves to justify low weight, yet I see the equivalent all the time with people of a weight outside the official guidelines in the other direction.
For me, as the poster I was replying to said, it does indeed go both ways, and I'm sorry but most (and rightly so) would find an equivalent post about someone's weight in the other direction would find it rather abhorrent. As the other post I referenced (which is presumably why mine got deleted) referring to 'teeny-tinies'.
Can you imagine if I responded to a post asking about 'concern' for someone outside the NHS guidelines in the other direction as 'fatty-watty who claims to eat less than they do?'
I'd never do that. Yet my post has been deleted whilst 'teeny-tinies' remains. A nasty little post about how we're all lying about what we eat. Nice, but apparently acceptable.