There are a couple of scenes where the kids are panting heavily, but it's nothing super graphic. There's also a scene where Nana attempts to suffocate herself, but that's about it.
While a head is not shown being squashed on screen it is implied that a head is crushed in a refrigerator door during the climax of the film. The head is off screen but you can see the person slamming the door and the body moving on the floor.
At about 1/3 of the way in, a boy mentions the father buying a 'funny card for a fat lady.' And a few minutes later, we find out the card is of the daughter, who is seriously struggling with being the victim of body-shaming.