Final answer:
A nutrition researcher investigates the alteration of food through cooking and storage, reactions to nutrients, and changing nutritional needs in different contexts.
Step-by-step explanation:
The type of dietitian who investigates how food is altered through cooking or various storage methods, how people react to different nutrients, and how people's nutritional requirements change in different situations is a nutrition researcher.
Registered dietitians, who aim to plan nutrition programs and often work in health care settings, require at least a bachelor's degree in dietetics, nutrition, food technology, or a related field, along with completion of a supervised internship program and passing a national exam. These professionals become experts in the chemistry and physiology of food, involving the biological functions of proteins, carbohydrates, and fats.