Until I feel like eating again. Listen to your body.
If you have had vomiting or diarrhoea then you ave had a "good clean out" !
With children after gastro I believe it is important to keep water intake up and also dry food like crackers or whatever they will accept. They soon let you know. However, after say, tonsillitis in children, I think it is vital that you get them eating as much as possible. If they end up needing tonsillectomy and they are underweight or suffering from poor nutrition, it seems to take them forever to start eating well and looking the part. I know we are always being told that there are too many overweight children in society, but I seem to miss them and see only the underweight, runny nosed, coughing ones.
I was always told you should wait at least 24 hours before eating after being sick and then only have something very plain and easy to digest, like jelly or a boiled egg.
My son however, cannot wait this long and always demands something horribly greasy like bacon for his recovery food! So I'm torn.... and wondering if there is any basis in what I've always thought or if it's ok to go with my son's instincts.
That's interesting as my brother and I have always maintained that we feel much better with a feed of greasy chips after being sick. . . . and we have not lived in the same house or even the same town for nearly 50 years and yet we have both come to this conclusion.
If you mean "ill in bed" sick (virus etc.) . . I wouldn't feel like eating for at least a day and maybe two. If you mean "vomit" sick . . . maybe I would last until my empty tummy started grumbling. I would then eat whatever took my fancy.