What have the littluns grown used to because of their eating habits?
In Chapter 4, the narrator of The Lord of the Flies explains that the littleuns have learned to adapt to their new situation: "They ate most of the day, picking fruit where they could reach it and not particular about ripeness and quality. They were used now to stomach-aches and a sort of chronic diarrhoea."
The fact that the youngest boys have grown accustomed to a constant discomfort as a result of their eating habits represents their general ability to adapt to life without grownups. They now can choose what they eat, rather than have meals prepared for them, and they live with the consequences of both good and bad food choices. This resilience is both a positive sign and a troubling one: many of the youngsters are indeed very resilient, as they cry less for their mothers than the narrator expects and they live as a group without bothering the older boys much, but the difficulty lies in their inability to take good enough care of themselves, which leads to illness and pain, and an appalling absence of good hygiene that endangers them and others.
In chapter 4, Golding writes that the littluns live relatively simple lives on the island, as they go around eating random edible fruit from trees and bushes. The littluns are not particular about what kind of fruit they eat, or its ripeness. As a result of their eating habits, the littluns begin to suffer from stomachaches and chronic diarrhea. The littluns begin relieving themselves at random locations near the platform, huts, and pool, which upsets Ralph. In chapter 5, Ralph holds an assembly to address numerous issues regarding following through with agreed-upon tasks. One of the topics Ralph mentions is where the littluns are relieving themselves. Ralph chastises the littluns for relieving themselves near the shelters, platforms, and areas with fruit. However, the littluns find it hard to control their bowel movements because they suffer from diarrhea and often cannot make it to the rocks by the beach to relieve themselves.
The "littluns" are suffering diarrhea and stomach ailments because of the amount of fruit they are eating on the island, because it is a daily occurrence they have become accustomed to it.