Only a person licensed or otherwise authorized to practice under this chapter shall practice dietetics/nutrition or provide nutrition care services or use the title “dietitian/nutritionist” or the words “dietitian” or “nutritionist” alone or in combination, or use the letters L.D., L.N., or any facsimile thereof, except as allowed by Chapter 34, Title 34. Nothing in this chapter shall apply to a physician licensed to practice medicine. Dietitians/nutritionists may offer advice and counsel on dietetics and nutrition as adjunct medical therapy when advice and counsel is given upon referral or directive of a licensed physician. Notwithstanding any other provision of this chapter to the contrary a person licensed to practice dietetics/nutrition or to provide nutritional care services shall not diagnose, treat, or prescribe for any human illness, injury, disease, impairment, or infirmity, or otherwise engage in the practice of medicine as that term is defined in Section 34-24-50.