My guess is, that you keep talking to the wrong women or you try to advance into a relationship too fast

In my experience, both women and men can and often do see past the physical outer and see the personality behind. The appearance is, as you say, the catalyst for initial attraction but if you keep at it, and maybe continue talking with people they should be able to see past their requirement of you not being skinny. If not, they may be using it as an excuse for not really feeling the convection. If they indeed like you as a person but not your body, then you are probably better off without them.

Also remember. No rellationship, is better than being in a bad rellationship. We all need to go through relationship’s to get better at being in one but there is no reason to look for one just to have one. It needs to be with the right person and looks play a pretty small part in this, in the long run