Orthorexia.
According to the National Eating Disorders Association {all emphasis mine}
Those who have an “unhealthy obsession” with otherwise healthy eating may be suffering from “orthorexia nervosa,” a term which literally means “fixation on righteous eating.” Orthorexia starts out as an innocent attempt to eat more healthfully, but orthorexics become fixated on food quality and purity. They become consumed with what and how much to eat, and how to deal with “slip-ups.” An iron-clad will is needed to maintain this rigid eating style. Every day is a chance to eat right, be “good,” rise above others in dietary prowess, and self-punish if temptation wins (usually through stricter eating, fasts and exercise). Self-esteem becomes wrapped up in the purity of orthorexics’ diet and they sometimes feel superior to others, especially in regard to food intake.
