It depends on the girl, and the guy. Im totally in love with my bf and love everything about him, including his physical looks, and he's not buff and only slightly toned.
So even though in general i prefer relativaly musclet guys, I love my bf just the way he is.
I say if you want a girl that will love you then don't change anything for her. If you just be you then you will find someone who loves you for you. And if she really loves you then she won't care bout ur physical looks.