This discussion is a good reminder that, despite what we think, most people don't notice us as much as we think they do. Which can be a relief in some instances, I'm thinking.

While I've appreciated when someone notices my weight loss, I'm hesitant to say anything to anyone else, mostly because I feel like it DOES imply that they did not "look great" previously. For the same reason, I don't compliment anyone when they are looking particularly nice.

I usually do say something if I know the person has been dieting or working out, but that's the only time.

I received a lot of comments during my weight loss journey. People (not related to me) just would not stop commenting. It became the daily running commentary and at one point it became too much. Although they mostly meant well, I realized that my weight loss seemed to affect everyone around me. I suppose I was in a certain box in some people's minds and they had a hard time accepting that I was changing. I had a hard time, too, but I was the one losing the weight and it was my own private personal matter.
I agree with Mo in what she said and actually it did happen to me that someone started complimenting me on my weight loss only to go on to say that before I was this big, while extending his arms horizontally, to which I gave him the most rotten look that I have ever given anyone and the comments stopped for a while. Then they resumed with people telling me that I was "disappearing" which I was not. I could go on and on with this, but my main message to you is, be proud of yourself, be healthy and enjoy. Too many comments can be a bad thing, too. I also agree with MaryK in what she says about how people treat her now vs how they treated her before.
As far as telling people when I see that they lost weight, most of the time I only compliment them in general. It is a difficult journey and each person has to figure out how much of it they want to do or are able to do. Losing weight is a very sensitive issue. For me, the comments have stopped for a while and I am more than relieved about that. Sometimes silence is golden.

I would want people to notice but it's such a loaded issue! For example, I had noticed from a picture you posted that you had lost weight, but was hesitant to comment. I might have said, you look great, but we say that to each other all the time here on YLF so it doesn't have as much impact. Maybe if someone says "you look great" you can help by saying "thanks, I've been on a weight loss program and I've already lost x pounds."

I'm very hesitant to comment on people's weight, because like Mo said, I'm worried they will think they didn't look good before. Even on this forum, I don't usually comment that an outfit makes them look thinner because I worry that they'll get offended. It's such a touchy subject.