She had to pay for a personal trainer and a dietician out of her own pocket, she says.
They had a dietician and I said I didn't need to eat anything.
1845, from diet (n.1) on model of physician. Earlier was dietist (c.1600).
dietitian di·e·ti·tian or di·e·ti·cian (dī'ĭ-tĭsh'ən)n. A person specializing in dietetics.