Yet despite her poor diet, Leah Frost, 17, is a svelte size eight.
Student Leah, from Leeds, said: "If someone puts something down in front of me and I know it isn't right it makes me feel anxious and scared to eat it."
She said she does supplement her spaghetti diet with other foods – but none of them are remotely green or healthy!
Sometimes she'll have chips, another time cheese, and when she's feeling especially adventurous, she'll risk a slice of sponge cake!
But according to a nutritionist, she is storing up health problems.
Sarah Hanratty, an expert nutritionist, said: "This diet is lacking in key micronutrients and is high in refined carbohydrate. Over the longer-term a diet like this can lead to insulin resistance possibly resulting in diabetes and obesity."
Despite being slim, Leah's bad diet does have an impact on her health. She feels tired all the time and her iron count is low.
Her mum Yvonne, 45, said: "Both Leah and I do worry about what she's putting her body through.
"She complains of feeling tired all the time and she has regular blood tests that always come back with some sort of deficiency.
"We got through phases where we will try really hard to get her to eat more normal food, and then we go back to square one when we realise that she's never going to change."