The Effect of Preadmission Energy Balance on Short-Term Medical Outcomes: Findings From the Study of Refeeding to Optimize Inpatient Gains

Purpose

Caloric restriction and excessive exercise create an energy imbalance with medical sequelae in restrictive eating disorders. We examined the effect of acute and chronic energy imbalance on admission illness severity and refeeding outcomes in adolescents and young adults with anorexia nervosa (AN) and atypical AN.

Methods

Secondary data analysis from the Study of Refeeding to Optimize Inpatient Gains, a multicenter randomized trial comparing higher- versus lower-calorie refeeding in 120 youth with AN or atypical AN hospitalized with medical instability. Vital signs were measured daily. Acute energy balance was calculated as caloric output (exercise recall plus estimated resting energy expenditure) subtracted from caloric input (dietary recall) before admission. Chronic energy imbalance variables included magnitude, rate, and duration of weight loss before admission. Regression analyses examined associations among energy balance, illness severity, and refeeding outcomes; dominance analyses examined the relative importance of energy balance.

Results

Among 82 participants (91% female), admission mean (SD) age was 16.5 (2.5) years, %median body mass index was 85 (10) and acute energy balance was −898 (678) kilocalories. Those with more negative acute energy balance before admission required more days (−0.18, [95% CI, −0.35, −0.02] p = .03) and kilocalories to restore medical stability (−431.10, [95% CI, −857.06, −5.13] p = .047). Acute energy balance was a more important predictor than weight suppression in determining these outcomes.

Discussion

More acute negative energy balance was associated with a need for more intensive refeeding, which supports the inclusion of preadmission dietary recall and exercise assessments, alongside weight history, to inform individualized refeeding protocols.