Okay to use the words "thin" and "skinny", but not "fat"

It's because most people in our culture are too fat and want to be thinner/lighter, so always see weight loss as a good thing and weight gain as a bad thing. (how much extra fat someone has may vary, but even people who don't look that fat or who aren't fat according to BMI or body fat percentage often want to lose a bit more fat to reach their ideal) ......Common courtesy tells most people that it's not polite to comment on bad things in other people, but it's nice to compliment them on good things. So they compliment people on losing weight and never mention it if someone's gained weight. I think most people don't think about this issue all that much, so only view it on this very superficial level, and don't question giving compliments to people on losing weight, or realise that some people might be underweight and trying to gain weight.

Yep people probably should be a bit more aware, but do bear in mind that most people don't give weight loss/gain more than a second's thought, so it's not like they're deliberately trying to annoy or upset you... mostly they have no idea at all. Probably the best thing for people you know reasonably well is to rehearse a very simple response, e.g. if they say "that's great you've lost weight" say something simple like "well it's not great, because I'm underweight and trying to gain weight" and leave it at that... it's enough to let them know what's going on and will probably stop them making the same comment again in the future.... for people you don't know, then just ignore them, or smile and say thank you (it was intended as a compliment) and don't feel obliged to explain anything to them

I think the real issue is disconnecting from what anyone says about your weight and body. It's just not worth the stress to get riled up, to think of a comeback, to feel indignant that someone doesn't realize "skinny" isn't a compliment. This is just my opinion, of course, but so many people on here (understandably) get upset about people's comments, but people will say what they will say. Maybe a rare person would change if you say something, but I find that if I work on not caring what people say, I feel more at peace.

My advice - when someone compliments you, even in a clumsy, awkward, or politically incorrect manner, accept it graciously and allow yourself a moment to feel good about yourself. Too many interactions in life involve indifference, callousness or rudeness, so appreciate the good intentions without over-thinking it...

This didn't fit the post as much as I'd meant it to. Deleting.

From losing the weight I've lost, I feel like people have told me I look amazing. They haven't necessarily used thin because well, let's face it, I have a long way to go still to be considered "thin". BUT what I'm getting at is that when I lost weight I started to look better because I dressed better, felt more confident and that projects almost like radiance about yourself: you just feel amazing (or at least I did) and that's that what people noticed.

When you're in a period of gaining, which I've gone through too to get to where I am, you aren't as confident, you might be stressed or upset or tired because you have so many things going on. All of these things gets rid of that confidence you project when you feel good.

I know "fat" is considered taboo and you're not supposed to mention when people are gaining weight because it's offensive, however I try not to say people look thin or skinny because in reality, I notice their whole attitude has changed because they feel good about themselves and I think that's probably why people notice you've lost weight. Maybe you don't feel so great right now because you're struggling with a balance but I try to think they have the best intentions

To call someone fat is seen as rude but to call someone skinny is somehow a compliment. As a person who has been both fat and skinny i sometimes wish that those close to me could be a bit more honest and tell me when I'm starting to slip. It's not healthy to be fat and you'd have to go a long way to convince me that fat people really are as happy as they claim they are - I for one was never happy when I was fat. I'm all for honesty but in a nice way - there's no need for nastiness or causing unnecessary hurt.

I tend not to comment on people's weight either. It's not my business, and I don't want to contribute to "fat talk." But the truth is that our society values thinness and people think they are paying you a compliment. It's hard because body issues are so wrapped up in what others think and what we think that they think. I think you are on the right track in acknowledging very clearly to yourself that your current weight is too low and noticing the effect others' words have on you. The more you are aware the better able you will be to let go of their words and stick to your truth. Best of luck in getting back to your healthy and happy weight range

Sorry, but "skinny" and "thin" do not have the negative connotation in our society that "fat" does.

Body shaming sucks no matter who it is happening to and nobody should be comfortable with it -- but our society, as a whole, sets thinness up as a goal women in particular should strive for. "Oh you look so thin!" can legitimately seen as a compliment - it can also be seen as an expression of concern - but that might phrased "You are looking too thin". "Oh you look so fat" will never be anything other than an insult.

In general, I don't think it's ever appropriate to comment on another's weight/fatness or thinness unless you are very close to a person and very careful about what you are saying and have nothing but the most genuine of concern tempered with a good measure of knowing another person's body isn't actually your business. But setting it up like thin/skinny have just as negative as a connotation as fat is well... in my opinion misguided. You can not like to be called skinny or thin -- that's totally understandable. But it has nothing to do with "fat" not being seen as appropriate to call another person.