How many letters does the top answer for “a specialist in the study of diet and nutrition” have?

The most common answer is dietician (9 letters).

Crossword clue: a specialist in the study of diet and nutrition

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

dietician 9 letters wn-def

a specialist in the study of diet and nutrition

dietitian 9 letters wn-def

a specialist in the study of diet and nutrition

a specialist in the study of nutrition 75% similar → nutritionist