In Little Miss Sunshine (2006), the scene where 10-year-old Abigail Breslin pulls in her stomach was carefully staged using a custom-made suit.
Except for Abigail, all the girls were actual regional beauty pageant veterans wearing their own real-life costumes, heavy hair and makeup, and performed their authentic, highly polished talent routines.
This heightened Olive's realization that she didn't look like the "traditional" competitors.