Even though, he brings up the issue of your weight/shameful to be with you, etc - this is not the core issue. In fact, it is likely that he is the one who might have doubts about his self-esteem/lack of security-identity. In most of such cases I doubt if he will change over the long run, unless you feel that he is able to recognize the real deficits in himself and will make a strong effort to correct these.