I don't think you can shame anyone into eating better by giving them a 'tongue lashing'. And it might even backfire.
They know that they ate things that they shouldn't have.
I think most of us know 'how' we should eat, it's the doing it that's hard.
Cut them some slack and move on. Continue to help them or not.
I know for myself, if someone tells me that I can't or shouldn't do something, it makes me want to do it even more.