Healthy eating fanatics who swear by ‘clean’ foods and quaff smoothies by the gallon could be the victims of a dangerous eating disorder which can lead to malnutrition and even death.

Individuals fixated with ‘naked’ or ‘raw’ ingredients and diets which ban processed or refined foodstuffs may be displaying symptoms of a purported condition called ‘orthorexia nervosa’.

Unlike anorexia, where sufferers restrict the quantity of the food they eat, sufferers of orthorexia, derived from the Greek word for ‘correct’, fixate on quality and strict internal rules.

But the rigid internal guidelines – which can even exclude entire food groups – can easily result in lethargy, weight loss and dangerous levels of malnutrition while sufferers labour under the misguided belief they are leading healthier lifestyles.

Food blogs promoting the latest fad diets and photo-sharing sites like Instagram – which has nearly 27,000,000 pictures labelled #eatclean, most of which depict supposedly healthy dishes or men and women showing off their sculpted physiques – are being blamed for condition’s rise.

The disorder was coined by Dr Steven Bratman in a 1997 paper, in which he said sufferers could be driven to despair by inadvertently ‘devouring a single raisin’ in violation of internal guidelines.