Young girls with eating disorders whose growth is stunted by undernutrition may achieve catch-up growth in height if they regain weight soon enough - but it takes several years, a new study shows.

The findings come from a Swedish study of girls who began losing weight before they started their menstrual periods.

“The current investigation shows that catch-up growth is achieved in underweight and growth-retarded girls with eating disorders once nutritional intake is sufficient to produce weight gain,” writes study author Dr. Ingemar Swenne of Uppsala University Children’s Hospital, in the International Journal of Eating Disorders

For most people with an eating disorder, weight loss begins at an age when little further growth is expected. Younger patients who have not yet completed puberty, however, may experience insufficient weight gain and stunted growth at an age when further increases in stature would normally be expected.

To investigate whether such patients are at risk of permanent short stature, Swenne measured catch-up growth in a study of 46 girls with eating disorders, such as anorexia nervosa.

At the start of the study the girls, who were 13 years old on average and weighed about 77 pounds, had heights that were below what was expected, based on their prepubertal measurements.

The girls quickly gained weight during their first year of treatment for the eating disorder, and continued to gain weight at a slower rate during the following years, Swenne reports.

However, the girls continued to lag even further behind in height during the first year, and it was only during their second to fourth years of treatment that they achieved catch-up growth, the study findings indicate.

“It is notable that the longstanding effect of undernutrition on growth does not reverse easily,” Swenne writes.

“The data therefore suggest that temporary weight loss or even temporary stagnation of weight gain during treatment may influence growth in stature for longer periods than hitherto recognized,” the researcher adds.

Three out of four girls began their periods during follow-up. By the last check-up, these girls achieved weights and heights similar to that of their peers in the general population and had resumed their pre-pubertal growth track. Those that had not begun menstruation experienced smaller increases in height and weight.

SOURCE: International Journal of Eating Disorders, December 2005.