Abstract
BackgroundThere is currently no standard clinical refeeding diet for the treatment of anorexia nervosa (AN). To provide the most efficacious AN clinical care, it is necessary to define the metabolic effects of current refeeding diets.MethodsAn activity-based model of anorexia nervosa (AN) was used in female rats. AN was induced over 7d by timed access to low fat (LF) diet with free access to a running wheel. Plasma hormones/metabolites and body composition were assessed at baseline, AN diagnosis (day 0), and following 28d of refeeding on LF diet. Energy balance and expenditure were measured via continuous indirect calorimetry on days −3 to +3.ResultsAN induction caused stress as indicated by higher levels of corticosterone versus controls (p < 0.0001). The rate of weight gain during refeeding was higher in AN rats than controls (p = 0.0188), despite lower overall energy intake (p < 0.0001). This was possible due to lower total energy expenditure (TEE) at the time of AN diagnosis which remained significantly lower during the entire refeeding period, driven by markedly lower resting energy expenditure (REE). AN rats exhibited lower lipid accumulation in visceral adipose tissues (VAT) but much higher liver accumulation (62 % higher in AN than control; p < 0.05) while maintaining the same total body weight as controls. It is possible that liver lipid accumulation was caused by overfeeding of carbohydrate suggesting that a lower carbohydrate, higher fat diet may be beneficial during AN treatment. To test whether such a diet would be accepted clinically, we conducted a study in adolescent female AN patients which showed equivalent palatability and acceptability for LF and moderate fat diets. In addition, this diet was feasible to provide clinically during inpatient treatment in this population.ConclusionRefeeding a LF diet to restore body weight in female AN rats caused depressed TEE and REE which facilitated rapid regain. However, this weight gain was metabolically unhealthy as it resulted in elevated lipid accumulation in the liver. It is necessary to investigate the use of other diets, such as lower carbohydrate, moderate fat diets, in pre-clinical models to develop the optimal clinical refeeding diets for AN.
Highlights
There is currently no standard clinical refeeding diet for the treatment of anorexia nervosa (AN)
Anorexia Rats were identified as anorexic when their body weight decreased to ≤75 % of initial weight. 75 % of initial body weight was chosen as the threshold for AN as we previously found that this was the mean percent ideal body weight of female adolescent AN patients who presented for inpatient medical care at Children’s Hospital Colorado [16]
Wheel running increased significantly in the 4 days leading up to AN diagnosis (Fig. 1b). This combination of increased physical activity and decreased energy intake precipitated the decline to an anorexic body weight, defined as 75 % of initial weight (90.1 ± 2.8 g), in 4 to 7 days (Fig. 1c). 75 % of initial body weight was chosen as the threshold for AN because we previously found that this was the mean percent ideal body weight of female adolescent AN patients who presented for inpatient medical care [16]
Summary
There is currently no standard clinical refeeding diet for the treatment of anorexia nervosa (AN). There is currently no standard, evidence-based clinical refeeding diet for the treatment of anorexia nervosa (AN) and nutritional treatment is focused primarily on calories and less on diet composition [4]. Studies in both rats and humans show that diet composition can affect the rate of weight regain following weight loss, impact the ability to maintain at a target weight, and dramatically alter metabolic health [5,6,7]. In order to provide the most efficacious clinical care for AN patients, it is necessary to define the effect of current refeeding diets on markers of metabolic health and use this information to develop optimal AN refeeding diets. Our ultimate goal is to achieve metabolically healthy weight gain in this population
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