People trying to hide an eating disorder will often split hairs when asked questions about their eating habits.

Brigham Young University researchers have developed a method for testing hairs to determine whether someone has an eating problem. Such a test could help doctors better diagnose patients who are reluctant to admit they have problems such as anorexia or bulimia.

Kent Hatch, a BYU biologist, helped create the test that examines a human hair for subtle differences in carbon and nitrogen amounts, which can be used to measure dietary patterns.

"People with eating disorders are often in denial, or they try to hide it," said Hatch, who was an author on a paper appearing in the journal Rapid Communications in Mass Spectrometry.

For example, Hatch said, a man was suspicious that his wife was not eating enough. The wife ate two Cheerios each morning, so that when her husband asked if she had eaten breakfast, she could truthfully say she had some cereal.

People taking diagnostic surveys also tend to bend the truth when asked questions about whether they purge or skip meals, said Steve Thomsen, a BYU communications researcher who was a study author.

The idea for a test came about because of Thomsen's research into how women's magazines influence ideas about body image. The communication researcher wanted a more objective way - beyond questions on a survey - of determining who had an eating disorder.

"We decided to see if we can develop a physiological or biological measure that would help us produce more accurate data," he said.

Thomsen happened to mention his problem to another BYU colleague who put him in touch with Hatch.

Upon hearing of the dilemma, Hatch was already devising a similar hair test intended to determine how much meat black bears were eating in various areas. The leap from fur to hair was not as large as one might think, Hatch explained.

The eating disorder test would serve a similar function as drug tests that analyze hair. The main difference is that testers would not be looking for foreign substances that appear in hair.

Instead, the test examines hair to look at differences in ratios of carbon 12 and 13 as well as nitrogen 14 and 15, elements that are always in hair. The ratios can change from one end of a hair to the other. A computer analysis looks at variation in ratio changes that may signal signs of an eating disorder.

Researchers collected hair samples from Orem's Center for Change, a clinic that specializes in treating eating disorders. Students in Thomsen's classes provided hair samples to serve as a control group against those from the clinic.

Hatch said the test produced positive results in 80 percent of the people known to have eating disorders. In the student group, researchers recorded false positives for about 20 percent of the tests. It is possible that some of the students had an eating disorder, but researchers also want to examine how vegetarian and vegan diets show up on the hair test, he said.

Researchers said more study is needed before a test could be developed for health professionals.

glavine@sltrib.com