Responses
Pochamani
http://www.mangago.me/read-manga/let_s_go_to_work_tomorrow/ (not really overweight, just thicker than characters in shojo mangas usually are)
http://www.mangago.me/read-manga/cousin/
http://www.mangago.me/read-manga/pochamani/
Thats all i could find for now, hope this helps (=・ω・=)
Are there any good shoujo mangas with an overweight MC? I just need to feel good about myself for a moment ┗( T﹏T )┛