I'm fat. Scratch that. I used to be fat. I still consider myself fat, though. Once you're fat, you never ever think of yourself as anything other than that at most times. I'm flabby; I have a gut that droops over my belt. It's not pretty. Depending upon how straight I'm standing, you can hardly tell that that's the case. This is probably why people tell me that I'm thin. "Let me take my shirt off for you and then you can tell me that again."
So, let's just be honest, guys. When you say that you're looking for "fit" guys, what you really mean is that you're looking for skinny/slender/slim guys. The flabby need not apply. And I don't. It doesn't matter than I can get up right now and go for a ten mile run without much, if any, difficulty. Oh, I'm fit, but I'm not the fit that you want. I can think of one person that I know that can't walk more than two blocks without considering hailing a taxi; you would consider him "fit" because he's very skinny. All other qualities aside, if you were to put us next to each other and select the "fit" person, you would (probably) pick him.
Speak the truth: you want someone skinny. And I'm done.