An ongoing, six-year study of 538 sets of twins in Michigan indicates that females who were in the womb with male twins have lower risk for eating disorder symptoms than females who were in the womb with female twins. Previous animal research has shown that females in the womb with males are exposed to higher levels of testosterone.

The new findings – from a team of MSU psychology researchers – are published in the March issue of the Archives of General Psychiatry, out today.

“From these findings, it appears that testosterone exposure could have a protective effect against the development of disordered eating,” said project researcher Kelly Klump, MSU associate professor of psychology and president of the Academy for Eating Disorders.

According to the academy, 10 percent or more of late adolescent and adult women report symptoms of eating disorders at any given time.

Klump said researchers have known for years that women are more affected by eating disorders than men and that “some of that is due to social influences such as beauty ideals around thinness for women that we don’t have for men.”

But the question of whether biological influences also play a role has been an understudied area, she said. The fast-growing MSU Twin Registry, which includes more than 1,200 sets of twins ages 6 to 30, provided a substantial research population, said Klump, who runs the registry with Alexandra Burt, assistant professor of psychology.

Kristen Culbert, lead researcher on the project and a doctoral student in clinical psychology, said while societal differences have typically been used to explain why women are more affected by eating disorders, the new research is “significant in suggesting a biological explanation.”

Being raised with a brother did not account for the effects, Culbert added. That’s because researchers also looked at females who were not twins but grew up with a brother and found that those females were at higher risk for eating disorder symptoms than females who shared a womb with and were raised with a male.

Klump said the findings could ultimately help improve the treatment of eating disorders.

“More and more animal researchers are discovering how testosterone affects brain development,” she said. “So if we know there are protective factors against eating disorders, we can potentially determine which areas of the brain might be particularly sensitive to prenatal testosterone exposure and use that information to identify new biological treatments.”

Also on the research team were Burt and Marc Breedlove, Barnett Rosenberg professor of neuroscience.

Note: If no author is given, the source is cited instead.

• Eating Disorder Research
• Men's Health
• Children's Health

• Eating Disorders
• Gender Difference
• Sleep Disorders

• Bulimia nervosa
• Eating disorder
• Twin
• Menopause
• Psychopathology
• Sexual dysfunction