Most generally, a nutritionist is somebody who provides expert advise on the health benefits or consequences of eating various foods, looking at the total diet of particular people and the overall nutritional value of it in relation to the clients needs.
Most nutritionists work in institutions such as hospitals, nursing homes, or the offices of various healthcare practitioners. In these cases, a nutritionist will typically prescribe a particular diet intended to promote the health of a patient with particular dietary needs. This could range from teaching someone with high blood pressure due to sodium sensitivity to cook using less salt, or providing an overall diet plan for someone suffering from obesity. Nutritionists might work with individuals who might be athletes doing high intensity training.
Additionally, some nutritionists manage large scale food preparation or catering services, which provide meals to institutions such as hospitals, schools, or prisons, insuring that clients are receiving properly nutritional meals. A smaller number of nutritionists do general research on the health benefits of different kinds of foods, and some do consulting work for companies who produce food products for the mass market (such as fast food chains and microwave dinners).
While the terms "nutritionist" and "dietitian" are often used interchangeably, in most states in the US only the title of "dietitian" is regulated, requiring a certain level of education or training, and a certification (the requirements vary by state to state).
The best resource to find a registered nutritionist need you is http://www.eatright.org which is the website for the American Dietetic Association ("ADA"). Simply click on the "Find A Registered Dietitian" button on the top right and you can find all registered nutritionists by simply locating your area on the map.





