What Are You Suppose To Feed A 4 Week Old Kitten?

We have a litter of kittens, and they are 5 weeks old. I would assume that the kitten food is for them being so young. BUT, if your cat can’t eat it, why do you want to give it to her?

I guess my question is this: If she doesn’t like it (or even worse, has diarrhea from eating too much of the stuff) what kind of vet will say “oh well lets just leave her hungry”? Or “she’ll get over any problems by tomorrow” – yes feeding an underweight cat with no access to water or food isn’t good.. but there’s nothing wrong with that!