All too often women with eating disorders cannot recognise they have a problem, or go to great lengths to disguise the problem from others.
This makes the disorder difficult to diagnose and even more difficult to treat.
But now researchers have developed a test which shows by analysing the carbon and nitrogen bound into hair fibres, it can be discovered whether a person has an eating disorder.
A multidisciplinary team of researchers from Brigham Young University (BYU) in Utah, say the test will show whether someone is battling with conditions such as anorexia nervosa and bulimia.
Hair it seems grows by adding new proteins to the base of the strand, and pushes the strand up out of the hair follicle and these proteins are affected by a person's nutrition.
A person's nutritional state is affected by eating patterns associated with eating disorders and because hair grows continuously, each strand consequently becomes a chemical diary of an individual's day-by-day nutrition.
The researchers set out to examine if protein patterns differed between people with eating disorders and others with normal eating behaviours.
They found that by careful statistical analysis of the data, they were able to give an 80% accurate prediction about whether a person had anorexia or bulimia, the two most common eating disorders.
The test was so powerful that it required only five stands of hair.