It's only shameful if its something you know you should be ashamed of. I've always played ice hockey on and off. Last season there's this kid on my team, skinny prick, 6ft tall and maybe 65kg soaking wet. I'm standing there after a game one day with my shirt off, all 6'2" and roughly 93kg of me and he starts talking about how fat I look. I was, maybe 15% bodyfat at the time and its the middle of fucking winter. I still had visible abs. Did I give a shit? No. Because I knew it was this kid being insecure about being so skinny and trying to build himself up by tearing me down.  If someone calls you fat and you aren't actually fat or don't actually care then it shouldn't fucking bother you. The only way anyone would ever be upset by it is if they knew, or suspected, that everyone thought they looked fat and are upset about being reminded of that or having it confirmed to them.