It's kind of odd that there seems to be a kind of impasse in many girls minds, usually overweight girls that being overweight doesn't somehow matter. There is from research I've done roughly 20-15 percent of the male population either into overweight women or accepting of them. I'm pretty certain they are like that genetically. I don't think you can convince a guy who is not into overweight women to accept them. So for these guys, roughly 85 percent of the male species including me overweight women are viewed with revulsion in terms of any thought as to getting with them, again a genetic response. That's not to say we wouldn't see them as ok to interact with but as far as dating or any thought of intimacy is concerned it's a no go.
Add to on top off that most of us guys that are not into overweight women including myself wouldn't even be able to get hard it is such a turn off, so dating one would be pretty pointless anyway. Many guys can stomach say thighs that are a bit flabby but too much flab there or elsewhere and it's a big, big turnoff. I would say if it bulges out off clothes that are normal size for your age/height then it is too much. Basically any sort of bulge like a tire is too much. So a little bit over as in say a few pounds but that can quickly turn to too much. A picture would be easier to show I guess.
Off course the opposite to that is a well toned girl (not muscley) but one without much fat apart from the boobs of course. That kind of girl is often scoring big points particularly if she shows off her figure with crop tops and the like. The face also plays a part but again for most overweight girls fat on the face tends to be a negative that will make a guy quickly want to move on.