I have decided that the words “Have you lost weight?” are one of the most important diet aids. If you can just hang on that long, until people start noticing, the question — and the implied compliment — is a great reinforcement.
To this end, I think we should all go around asking people if they’ve lost weight. Some of those people may have just started diet and exercise programs and (even though you haven’t actually noticed any change) the fact that you seem to notice may be just the encouragement they need.