Dietetics

[Sarah]

That part of the medical or hygienic art which relates to dietor food; rules for diet.To suppose that the whole of dietetics lies in determining whether ornot bread is more nutritive than potatoes. H. Spencer.

[Kai]

the scientific study of the food that people eat and its effects on health

[Jessica]

The branch of knowledge concerned with the diet and its effects on health, especially with the practical application of a scientific understanding of nutrition.