A nutritionist is a professional who specialises in the science of nutrition and advises on diet for health, performance, or disease management. The title’s meaning varies by country: in the UK, “Registered Nutritionist” is a protected designation awarded by the UK Voluntary Register of Nutritionists to graduates of accredited degree programmes, while plain “nutritionist” is not legally protected and can be used by anyone. This contrasts with “dietitian,” a statutorily regulated title across much of Europe and North America. Qualified nutritionists work in public health, sports nutrition, food industry, research, and private practice, translating evidence into practical eating advice. Consumers seeking advice should check credentials: accredited degrees, professional registration, and membership of bodies like the Nutrition Society signal genuine expertise in a crowded marketplace.