I've had experiences similar to DebSP's. People seem to think it's quite ok to comment when I choose not to eat cake or candy at work or when I eat a food that might be considered "different." It doesn't happen where I work now, and they don't make comments either, when I walk in wearing my bike clothes. Only praise.
I guess what I don't get, is how people think it's ok to *say* something in these situations. I always told my kids, "You can think it, don't say it."