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Changes in resting energy expenditure and body composition in anorexia nervosa patients during refeeding

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Abstract

Accurate prediction of the energy level necessary to promote weight restoration in patients with anorexia nervosa would be clinically useful. Resting energy expenditure (REE), respiratory quotient, and body composition were measured in 10 nonmedicated women with anorexia nervosa during a vigorous refeeding protocol. REE was measured three times per week by open-circuit indirect calorimetry after an overnight fast. Subjects ranged in age from 19 to 38 years and weighed 39.9 ± 4.3 kg (mean ± standard deviation) at admission. The refeeding protocol was as follows: phase 1, 1,200 kcal/day for 1 week (baseline); phase 2, an increase of 300 kcal/day for 1 week; phase 3, 3,600 kcal/day until target weight was reached; phase 4, 1,800 to 2,800 kcal/day (stabilization). REE was 30.0 ± 6.4, 33.5 ± 6.7, 37.3 ± 6.6 and 34.5 ± 4.4 kcal/kg body weight during phases 1, 2, 3, and 4, respectively. The Harris-Benedict equation overestimated phase 1 24-hour REE by a mean of 14% and underestimated REE in phases 2, 3, and 4 by a mean of 8%, 24%, and 23%, respectively. Skinfold measurements revealed percent body fat to be 12 ± 4% at admission and 19 ± 5% at discharge, with a mean of 48% of the weight gained during refeeding attributable to increased body fat. These findings indicate that refeeding in anorexia nervosa is associated with increased REE, which cannot be explained by increased body mass, and that caloric requirements for weight restoration in patients with anorexia nervosa are best determined by monitoring individual response.

Section snippets

Subjects

Ten consecutively admitted women, aged 19 to 38 years, were recruited for this study. The patients had been admitted voluntarily and consented to the overall treatment regimen. Subjects were nonmedicated, had no endocrinopathic diseases, and met established criteria for anorexia nervosa (1). All were at least 15% below expected weight for height upon admission. Seven reported some bulimic behavior before hospitalization, and three appeared to have controlled their weight primarily through

RESULTS

The refeeding protocol promoted weight gain in all subjects, as predicted. Ten patients completed phases 1, 2, and 3, and six patients remained hospitalized long enough to complete phase 4. The refeeding regimen lasted a mean of 6.3 weeks. None of the patients experienced adverse metabolic or physiologic side effects in response to the regimen.

The Table lists descriptive characteristics of the total group during phases 1, 2, and 3 of the refeeding protocol as well as characteristics of the six

DISCUSSION

Results from our study demonstrate that refeeding to restore weight in anorexia nervosa patients is associated with an increase in REE, even when corrected for increased body mass. At baseline, estimates of REE derived from predictive calculations were found to overestimate basal energy expenditure, but during weight restoration these figures underestimated expenditure substantially.

In a study of 29 patients with anorexia nervosa, Walker et al (18) observed that a mean excess of 5,026 kcal was

APPLICATIONS

Adult patients with anorexia nervosa are a heterogeneous group, although low initial REE has been consistently reported, most likely in response to semistarvation. However, results from this study confirm that REE is likely to be higher than predicted during refeeding, presumably mediated by altered hormonal or metabolic status. High-energy diets may be clinically necessary to promote continued weight gain in these patients.

More importantly, monitoring REE levels and response to refeeding

Acknowledgements

The authors thank the staff of the Clinical Research Center, especially Constance Adair, MS, RD, for support and for obtaining the body composition measures. The authors also thank Robert Bartlett, MD, of the Department of Surgery and Adam Drewnowski, PhD, of the Program in Human Nutrition, University of Michigan, Ann Arbor, for their guidance and support.

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    This study was supported by CRC grant 5M01RR00042.

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    D. D. Krahn is currently an associate professor in the Department of Psychiatry, University of Wisconsin, Madison, WI 53705.

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