Of all Expansions...

There often are times when people eat. For most a few times a day.

There are other times when people absolutely stuff themselves. This hopefully doesn't happen as often. But when animated characters do it, it goes right to their tummy and increases their size and figure in a similar manner to filling a balloon. This new-found girth usually goes away pretty easily, but can stay around for a while. A usually-minor form of this is Truth In Television.

Also, there are times when people don't have anything to eat for a long time, and then they play the trope exceptionally straight. They get kwashiorkor.

The girth can also come from water, or even air or helium. In the case of the latter, one also receives other qualities of a balloon.

There is a fetish for this out there. Or So I Heard.

Examples:

1. In Gintama, Kagura stuffs herself until she gets a full, big stomach in episode 74, episode 153 and ending 14.
2. In Kyouran Kazoku Nikki, Kyouka eats too much cake and gains a full, huge belly in episode 2.
3. In Kiddy Girl-and, Rubis eats a whole banquet and gets a huge belly in episode 11.
4. In Demashita Powerpuff Girls Z, the girls eat too much ramen and gain big bellies in episode 15.
5. In The Third The Girl Withthe Blue Eye, Millie gets a full, slightly bigger belly after eating in episode 7.
6. In Air Master, Renge eats until she gets a balloon belly in episodes 3, 24 and 26.
7. In Bamboo Blade, Satori stuffs herself at lunch and gets a balloon belly in episode 17.
8. In Cosplay Complex, Delmo stuffes herself and gets a big belly in the opening.
9. In Divergence Eve, Misaki eats a lot and gets a full, big belly in the ending.
10. In Galaxy Angel, Milfeulle makes a C-faced girl eat too much cakes and gets a full, round belly in episode 47.
11. In Galaxy Angel Rune, Lili and Anise get balloon bellies in an eating contest in episode 12.
12. In High School Girls, Yuma compites with Eriko in a ramen eating contest and Yuma gets a balloon belly in episode 8.
13. In Happy Lesson, Satsuki loses to Hazuki in an eating contest and gets a full, big belly in episode 4.
14. In Jungle Wa Itsumo Hale Nochi Guu, Guu gets a big belly after eating people in episode 14 and Ova Haré+Guu FINAL 2.
15. In Princess Be Careful, Mari Kode eats too many apples and gets a full, big belly in episode 2.
16. In Koihime Musou, Chouhi gets a big belly after entering an eating contest in episode 7.
17. In Macademi Wasshoi, Falce drinks a whole drink in her mini-form and gets a full, big belly in episode 4.
18. In Ojamajo Doremi, Lala is seen with a full belly in Ojamajo Doremi Sharp episode 16.