The findings, published in the January issue of the Journal of Adolescent Health with an accompanying editorial, challenge the current conservative approach to feeding adolescents with anorexia nervosa during hospitalization for malnutrition.

The American Psychiatric Association, American Dietetic Association and others recommend starting with about 1,200 calories per day and advancing slowly by 200 calories every other day. This "start low and go slow" approach is intended to avoid refeeding syndrome -- a potentially fatal condition resulting from rapid electrolyte shifts, a well-known risk when starting nutrition therapy in a starving patient.

The UCSF study is the first to test these recommendations, which have been in place since 2000. "Our findings show that the current recommendations are just not effective," said Andrea Garber, PhD, RD, associate professor of pediatrics in the Division of Adolescent Medicine at UCSF, who led the research with colleagues in the UCSF Adolescent Eating Disorders Program.

Study participants were hospitalized due to signs of malnutrition, including low body temperature, blood pressure, heart rate and body mass index. The vast majority of the 35 primarily white, female adolescent patients received low calorie diets based on the current recommendations. Patients were fed six small meals per day, and when they refused food, they were given high calorie liquid supplements as a replacement. The patients' vital signs were monitored closely, with their heart rates measured continuously and electrolytes checked twice a day.

While the low calorie diets did prevent refeeding syndrome for those patients, about 83 percent of them also experienced significant initial weight loss and no overall weight gain until their eighth day in the hospital. This finding represents "a missed opportunity," according to Garber.

"Studies show that weight gain during hospitalization is crucial for patients' long-term recovery," she said, "we have to make the most out of their short time in the hospital."

Although 94 percent of patients in the study started on fewer than 1,400 calories a day, it included a range of diets from 800 to 2,200 calories. This range allowed the researchers to examine the effect of increasing calories. According to Garber, two important findings emerged:

• The calorie level of the starting diet predicted the amount of weight that would be lost in the hospital. In other words, those on lower calorie diets lost significantly more weight.
• Higher calorie diets led to less time in the hospital. In fact, Garber said, "we showed that for every 100 calories higher, the hospital stay was almost one day shorter."

While the study finds that current recommendations are too cautious, it raises other questions, according to the research team. For example, while a shorter hospital stay may reduce insurance costs, patients may not be ready to go home yet.

"Shorter is not necessarily better" said Garber. "We have to consider the potential implications down the line, both psychological and emotional."

Another unanswered question relates to refeeding syndrome, which remains "a very real fear," according to Barbara Moscicki, MD, a professor of pediatrics in the Division of Adolescent Medicine at UCSF and senior author on the paper. Moscicki says that the team is proceeding cautiously since more aggressive approaches to feeding and supplementation have not yet been well studied.

Nevertheless, the researchers say that the study results are a promising start because no adverse events were seen in the study subjects on the higher calorie diets. "If we can improve weight gain with higher calories," Garber said, "then we're on the right path."

Other co-authors are Nobuaki Michihata, MD, Katherine Hetnal, and Mary-Ann Shafer, MD, all of UCSF. The study was conducted in the Pediatric Clinical Research Center through UCSF's NIH-funded Clinical and Translational Science Institute (CTSI).

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

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