My WW leader last week was talking about something that I do all of the time and now I see how wrong it is both to myself and to others. Specially, this is when someone makes a compliment on weight loss and you say "Thanks, but I still have XX pounds to lose" or "Thanks, but I am still really fat..".
Not only does it hurt the person who is trying to say something nice, but you aren't allowing yourself to be happy with what you have been doing and the choices that you've made.
So, if someone says something nice to you, say "Thanks". (with no buts!).