IPA: //njuˈtrɪʃənɪst//
KK: /nʊˈtrɪʃənɪst/
A person who is trained and knowledgeable about food and nutrition, helping others to make healthy eating choices.
She consulted a nutritionist to improve her diet and overall health.
Nutritionist → It is formed from "nutrire" (meaning to nourish) and the suffix "-ist" (meaning one who practices or specializes in). A nutritionist is someone who specializes in nourishing the body through food and diet.
Think of someone who 'nourishes' ('nutrire') the body and is a specialist ('-ist') in food and diet.