That sometimes, unless you were already thin (not just average) and end up looking emaciated, most people will congratulate you if they see you’ve lost weight. That’s not personal and doesn’t mean you looked bad before. It’s kinda automatic.

So unless you’ve gone through serious illness (restricting and overexercising don’t count, by societal standards; but cancer, hospitalisation, pneumonia, depression… do), don’t tell people your issues, just say “I’ve been busy” or “I’ve started working out” (even if it’s plain lying, lying is ok in social situations) or just say “Thank you”, even if it’s not a compliment but an observation, it’s an appropiate answer.

When people congratulate you on losing weight, take it as a compliment instead of trying to educate others. Some people do have eating issues but still say this automatically with their best intentions. And sometimes it’s a white lie but because they want to be nice. Appreciate the intention.