While I don't think IF hurts children, and I think children naturally IF (my two year old will often refuse to eat much, and then eat tons later on etc.) I don't think it's ethical to force ANYONE to IF.
I think kids need the ability to eat when they are hungry and stop when they are full. They don't need specific foods to do this though, and will adjust. We don't have bread, and my toddler doesn't miss it. He did for about 3 days, but I always had alternatives. Sometimes he refused them and was "ravenous" later, but then ate something else.
The more I see the less I know for sure.