I thought so too. But with the amount of people arguing that they, or certain others, aren't fat I realised that fat didn't simply mean a bit overweight for some.
To me, fat is someone who is quite obese. Someone who is a bit overweight doesn't look fat to me, I mean if you dress flatteringly you won't have stuff sticking out and you can still look hot
I would take this matter as personal as possible, because I'm right now in the exact situation. I feel that I look overweight and look a bit chubbier also finding difficult to make quick moves. So this is what I got to say about adjective fat.....