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Stanford researchers expand comparison of males and females with anorexia

anorexia-apple2Research on anorexia nervosa often excludes boys and men, who make up about 10 percent of those affected by the serious eating disorder.

This omission has made it hard for doctors to know if the disease has different consequences in boys and girls, which is a problem because the proportion of male patients diagnosed is rising. Since anorexia radically alters body composition, and the sex hormones estrogen and testosterone also influence bone density, fat mass and muscle mass, it makes sense to question whether the disease changes males' and females' bodies differently. Scientists also want to know how having an eating disorder may affect men throughout life -- more on that below.

Recently, a team of researchers from Stanford and other universities, led by Jason Nagata, MD, a former pediatrics resident at Stanford who is now at the University of California-San Francisco, have published a series of papers to help fill this knowledge gap. In September, the team published findings that among teens who had had anorexia for a short time, bone density didn't differ between male and female patients. Instead, the strongest determinant of low bone density -- a marker for fracture risk -- was how malnourished patients were.

Today, a paper in the Journal of Adolescent Health compares overall body composition in male and female anorexia patients. In healthy teens, girls typically have more fat mass; boys, more lean mass. The new study of 16 boys and 119 girls who were patients in the Comprehensive Eating Disorders Program at Lucile Packard Children's Hospital Stanford found that both fat mass and lean mass (which is muscle and other tissues that aren't fat or bone) were significantly lower than normal in boys and girls with anorexia. Patients' degree of malnourishment, not their gender, was the main determinant of their body composition.

The team is also publishing a paper in the Journal of Bone and Mineral Research that looked at bone fracture rates in boys, girls, men and women with and without anorexia. The study, which drew upon a large data set from the United Kingdom, included 9,239 females and 556 males with anorexia, as well as almost 98,000 control participants without eating disorders. The researchers found that girls and women with anorexia had increased fracture risk, particularly at the hip/femur and the pelvis. For boys and men younger than 40, anorexia was not linked to increased fracture risk, but in men who were 40 or older, anorexia did raise fracture risk, especially in the vertebrae.

Overall, the data imply that malnutrition plays a bigger role than gender, and that disease severity should guide whether doctors decide to order tests such as bone scans for their anorexic patients.

On another front, a separate team at Stanford, led by Shiri Sharvit, PhD, and James Lock, MD, PhD, is working to help parents who have eating disorders learn how to establish healthy eating behaviors in their young children. Their project started with mothers only, but they plan to begin enrolling dads in March. "There is almost no information on men who are fathers and have eating disorders, partly because there is a lot of stigma," Sharvit said. Her research team has established a 12-session program to help parents with eating disorders avoid problems in how they communicate with their kids about food. Information for prospective participants is available online, and mothers and fathers with any past or current eating disorder diagnosis (not just anorexia) are invited to join.

Previously: Does anorexia affect boys' and girls' bones differently? Probably not, Families can help their teens recover from anorexia, new study shows and A growing consensus for revamping anorexia nervosa treatment
Photo by Benjamin Watson

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