Does anyone ever SAY anything?

It might also be that people are reluctant to feed into the "fat is ugly, thin is beautiful" stereotype. I know that if I see someone and I notice that they've lost weight, if I comment at all I'm always very careful with my phrasing to make sure that I don't imply that the only reason they look good now is because they are thinner. I don't like to say anything that might make someone more likely to equate their self-worth or attractiveness with the shape of their body. Having struggled with an eating disorder, this is a big thing for me :-)

So, there might be people who do notice, and do think you look good, but don't want to say "Oh, you've lost weight, you look great!" because they don't want to suggest that if you happened to gain the weight back you'd no longer be as good or attractive or whatever.