you're looking good??

i've heard a lot of back and forth about whether it's polite to tell someone they look good when they've obviously been losing weight, but never really got a straight answer about it. i want to tell them so they know it's working and be encouraged, but are they gonna be offended because it insinuates that they didn't look good before? i guess it really depends on the person you're talking to but if someone tells me i'm looking good or thinner, i'll totally take it...unfortunately, there's no chance of that for now.