Nutritionist

[Becky]

usage (noun)
A title claimed by many have-been hollywood types, wannabe doctors, and your regular [garden variety] hollywood fitness guru. There is no legal definition therefore allowing any [charlatan] to use it. Normally used to imply that the person has some knowledge on the science of biochemical reactions which occur in energy expenditure and metabolism as an organism converts food into usable energy-but notice they never use R.D. after their name, as they would be [prosecuted] for impersonating real scientists.

[Hina Muqadas]

A person who studies or is an expert in nutrition.

[Jason Yan]

an expert on the subject of nutrition: