He’s not human, he’s a Time Lord. Just because he looks sort of humanlike from the outside doesn’t mean he’s like a human on the inside. He has things humans don’t, like two hearts, and his senses are only superficially similar. Eyesight, hearing, smell, touch, taste, all so much more sensitive than a human’s, and regeneration just exacerbates everything.
It’s not his fault everything he asks for tastes so… bleurgh! He’s trying to work out what his new body needs, he just keeps getting it wrong.
Fish fingers and custard though… A little of what you fancy does you good.