Orthorexia nervosa

An obsession with eating healthy foods:

The condition was named by a Californian doctor, Steven Bratman, in 1997, and is described as a "fixation on righteous eating". Until a few years ago, there were so few sufferers that doctors usually included them under the catch-all label of "Ednos" – eating disorders not otherwise recognised...

"Other eating disorders focus on quantity of food but orthorexics can be overweight or look normal. They are solely concerned with the quality of the food they put in their bodies, refining and restricting their diets according to their personal understanding of which foods are truly 'pure'."

The obsession about which foods are "good" and which are "bad" means orthorexics can end up malnourished. Their dietary restrictions commonly cause sufferers to feel proud of their "virtuous" behaviour even if it means that eating becomes so stressful their personal relationships can come under pressure and they become socially isolated...

"Those most susceptible are middle-class, well-educated people who read about food scares in the papers, research them on the internet, and have the time and money to source what they believe to be purer alternatives."

More at the Guardian link.