A few steps closer to answering the unanswered questions about higher calorie refeeding

Refeeding is the first step in long-term nutritional rehabilitation of patients with anorexia nervosa (AN). It may begin in the outpatient setting or in the hospital, if close medical and/or psychiatric monitoring is needed. In either case, early weight gain appears to be crucial for recovery. In hospital, faster weight gain [1] and higher weight upon discharge [2, 3] predict weight recovery at 1 year. In outpatient psychotherapy, substantial early gain (at least 0.43–0.86 kg/week during the first 4 weeks) predicts both weight and cognitive recovery at 12 months [4]. The importance of weight gain, however, must be balanced with the need for safety. Around the time of World War II, deaths were documented during refeeding in prisoners of war and the refeeding syndrome was first described [5, 6]. These sobering reports launched a 60-year period of extremely conservative approaches, with consensus-based recommendations for AN beginning around 1200 cal per day (kcal/d) and advancing slowly by 200 kcal every other day [7–9]. During the decades that this “start low and go slow” approach has been the standard of care in AN, only a handful of cases of the refeeding syndrome have been reported and this has been lauded as an indication of the safety. However, recent studies linking LCR to poor weight gain [10–12] and prolonged hospital stays [11, 12] have contributed to recognition of the “underfeeding syndrome” [13] and spurred interest in Higher Calorie Refeeding (HCR). There is no consensus as of yet on the definition of HCR, and clinical approaches vary widely. Nevertheless, it is clearly a “hot topic”: 85% of the refeeding studies published from 2010 to 2015 started with higher calories than recommended (≥1400 kcal/d) [14]. This issue of the Journal of Eating Disorders is on the frontline of this movement. The studies published in this issue share core attributes: all three are retrospective chart reviews examining short-term, meal-based refeeding in moderately malnourished [75–85% of median Body Mass Index (mBMI)] adolescents (ages 14–16 on average), who were diagnosed with eating disorders and hospitalized for medical stabilization. However, several unique features further our understanding by addressing important unanswered questions. Is HCR safe? No study to date has established the safety of a refeeding approach, and perhaps no study could ever truly do so, since a massive study population would be required to examine the full spectrum of features of the rarely occurring refeeding syndrome. Thus, we must continue to use very careful language around safety, acknowledging that electrolyte shifts are at best only early indicators of the risk for development of the refeeding syndrome. This was the focus of Maginot et al., who compared serum phosphorus, potassium and magnesium during refeeding on LCR (starting around 1185 kcal/d and advancing by about 90 kcal/d) versus HCR (starting at 1781 kcal/d on average and advancing by about 100 kcal/d). Among 89 participants, the authors found no association between starting kcal prescription and hypophosphatemia, hypokalemia or hypomagnesaemia in the first 72 h. Another unique aspect of this study was its subanalysis of severely malnourished patients: almost 30% of the study population was admitted with mBMI < 75%. Only two prior studies of HCR have had sufficient sample sizes to do this (as reviewed in ref 14), both reporting higher rates of refeeding hypophosphatemia Correspondence: [email protected] Department of Pediatrics, Division of Adolescent and Young Adult Medicine, University of California, San Francisco, Benioff Children’s Hospital, 3333 California St., Suite 245, Box 0503, San Francisco, CA 94118, USA