How do Muslims fast for a whole month without getting gallstones?

Is there some trick to it? Like eating a lot during the night or simply a habit? Or do they get sick often? 🤔

Edit: since it appears I wasn't clear enough, yes, I know that they don't eat anything while the Sun is up and that they have meals before sunrise and after sunset, I meant is that enough for their body or do they get sick more often than people that don't fast in that way or don't starve themselves for any other reason.