dietetist

from The Century Dictionary.

• noun One who lays great stress upon diet; a physician who gives the first place to dietetics in the treatment of disease.

from the GNU version of the Collaborative International Dictionary of English.

• noun A physician who applies the rules of dietetics to the cure of diseases.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A physician who applies the rules of dietetics to the cure of diseases.