In Vol. 07 of Maria+Holic, Kanako Miyamae sucking or eating a tube that made her fatter and someone is force her to lose weight. In vol.08 of Maria+Holic, She still fatter and she getting thiner and thiner until she became too thiner and the girl feed her lot a food and became fatter again, anf she have to start all over again.
Here a link to Maria+Holic Raw Manga.
http://the-raws.blogspot.com/2010/06/mariaholic.html