A study released on Monday by researchers from Utah's Brigham Young University found that examining carbon and nitrogen in the proteins of hair could reveal information about a person's day-to-day nutrition.

Lead author Kent Hatch from the university's department of integrative biology said clinicians could use this as a tool to help diagnose such disorders as anorexia or bulimia because many sufferers lied or did not recognize their problems.

Hatch said current methods used to diagnose and monitor patients suffering from eating disorders relied heavily on questionnaires and interviews.

"Rather than waiting until it's extremely obvious that they've fallen off the wagon if you will, they might be able to take some hair and see whether they've been sticking to the treatment regime that has been prescribed for them, rather than relying on the honesty of the person," Hatch told Reuters.

Dietary changes can be measured in head hair after a month of growth and the team is now looking at leg hair and beard growth as well, which could show signs of changes in diet after only six days.

Hair grows by adding new proteins to the base of the strand and pushing the strand up out of the hair follicle. The make-up of the proteins is influenced by a person's nutrition at that moment, researchers said.

The study, published in the journal Rapid Communications in Mass Spectrometry, compared the chemical pattern in strands of hair between 20 young women seeking treatment for eating disorders and 22 others with normal eating behaviors.

Statistical analysis of the data enabled researchers to give an 80 percent accurate prediction about whether a person had anorexia or bulimia - the two most common eating disorders. The test required only five stands of hair.

Doug Bunnell, a clinical director of the Renfrew Center of Connecticut that specializes in eating disorders and a board member of National Eating Disorders Association, said extra evidence could help patients in the process of coming to terms with their condition because motivation for treatment was key.

"What this might be useful for is helping present a case to the patient that she really has a disorder that is affecting her physiological health, because one of the hallmarks of these illnesses is denial," Bunnell told Reuters.