Resting energy expenditure and plasma leptin levels in anorexia nervosa during acute refeeding

Energy expenditure during nutritional rehabilitation: a scoping review to investigate hypermetabolism in individuals with anorexia nervosa

BACKGROUND

Weight gain and nutritional rehabilitation are essential first steps to achieve medical stabilization in anorexia nervosa, and frequent resistance to weight gain requires patients to consume high kilocalorie loads. Adaptive hypometabolism is common when patients begin treatment, and rebound hypermetabolism is suspected to be a significant barrier to weight gain. The aim of this review was to summarize existing data describing metabolic changes in anorexia nervosa during weight restoration. The reported findings challenge current hypotheses of weight gain resistance and highlight key areas for future research.

METHODS

Using scoping review guidelines, three databases were searched for studies investigating metabolic changes in anorexia nervosa before and after renourishment. Two reviewers systematically screened the titles and abstracts of 447 articles, and full-text versions of 106 studies were assessed for eligibility. A total of 36 studies were included for review. Data regarding the study description, sample population (including age, weight, BMI, duration of treatment, and caloric intake), and metabolic variable descriptions were extracted.

RESULTS

Female patients with anorexia nervosa from studies across 13 countries were included. Across the studies, average BMI increased from 13.7 kg/m2 at admission to 17.57 kg/m2. Patients presented to treatment with clinically reduced energy expenditure levels. After varying levels of nutritional rehabilitation and weight restoration, measured energy expenditure increased significantly in 76% of the studies. Energy expenditure values at the second timepoint increased to the standard range for normal weight female teenagers and adults. Despite these increases, the studies do not indicate the presence of a hypermetabolic state during renourishment. Additionally, all studies including both measured and predicted energy expenditure reported that predicted energy expenditure overestimated measured values.

CONCLUSION

This study provides a detailed evaluation of the literature investigating energy expenditure and metabolic rate in patients with anorexia nervosa before and following a period of renourishment. The findings from this review identify important gaps in the current beliefs of energy expenditure in anorexia nervosa and highlight a need for further exploration of metabolic alterations during weight restoration.

Energy metabolism and body composition in long-term recovery from anorexia nervosa

OBJECTIVE

The aim of this study was to determine if energy metabolism and body composition differ between women recovered from anorexia nervosa for 2 or more years (RAN) and control (C) women.

METHOD

Using a cross-sectional design, 16 RAN and 18 C women were studied. Respiratory quotient (RQ) and resting energy expenditure (REE) were measured using indirect calorimetry and body composition using dual energy X-ray absorptiometry.

RESULTS

The REE between RAN and C women was not significantly different, even when adjusted for body composition. However, RAN women had a higher rate of fat oxidation (p = .015), controlling for diet and body composition. There were no significant differences between the groups for body composition, percent body fat, or percent truncal fat mass.

DISCUSSION

Although RAN women have a higher rate of fat oxidation, there were no significant differences in REE or body composition when compared with C women.

Leptin and body weight regulation in patients with anorexia nervosa before and during weight recovery

BACKGROUND

Leptin has been considered a starvation hormone, but its role in malnourished patients is unknown.

OBJECTIVE

We aimed to characterize the role of leptin in metabolic adaptation in women with anorexia nervosa (AN).

DESIGN

In a cross-sectional study, 57 women with AN [mean (+/-SD) body mass index (kg/m(2)) on admission: 15.2 +/- 1.5] were compared with 49 healthy, normal-weight women (mean body mass index: 22.3 +/- 2.3). Nineteen patients were reinvestigated during weight gain 43 and 84 d after baseline. We measured serum concentrations of leptin, soluble leptin receptor, insulin, ghrelin, and thyroid hormones [thyrotropin, triiodothyronine (T(3)), and thyroxine]; fat mass (FM) and fat-free mass (FFM); resting energy expenditure (REE); energy intake; and eating behavior.

RESULTS

Compared with values in the control women, leptin, T(3), REE, FM, and FFM were lower in the women with AN, but the leptin secretion rate was not significantly different. Leptin correlated with FM (r = 0.83, P < 0.001), T(3) (r = 0.68, P < 0.001), respiratory quotient (r = -0.47, P < 0.001), and REE (r = 0.58, P < 0.001). The association with REE weakened after adjustment for FFM and disappeared after further adjustment for T(3). Hunger and appetite had positive, whereas satiety and restraint had negative, associations with leptin. During weight gain (9.0 +/- 3.3 kg in 84 d), serum leptin and the leptin secretion rate increased. Changes in leptin secretion were associated with energy intake and REE. The initial changes in the leptin secretion rate (ie, the difference between baseline and 43 d) were negatively associated with changes in body weight from 43 to 84 d.

CONCLUSIONS

Leptin contributes to metabolic adaptation in women with AN. The leptin response is associated with weight gain.

Caloric requirement for refeeding inpatients with anorexia nervosa: the contribution of anxiety exercise, and cigarette smoking

BACKGROUND

Refeeding inpatients with anorexia nervosa (AN) is costly, stressful, and can precipitate the refeeding syndrome. Caloric intake is usually increased gradually from a low starting point until a steady weight gain is achieved. There is no reliable equation that predicts the number of calories required for a weight gain. It was our clinical suspicion that anxiety, exercise, and cigarette smoking might increase the caloric need for refeeding.

METHOD

We conducted an observational cohort study of 17 females with AN admitted to an inpatient eating disorder unit for refeeding. We estimated the energy intake by observation, the caloric expenditure due to exercise with a triaxial accelerometer, the number of cigarettes smoked by history, and the anxiety by the Beck Anxiety Inventory (BAI).

RESULTS

Neither anxiety, exercise, or cigarette smoking predicted the caloric requirement for refeeding, individually or in combination.

DISCUSSION

Our data suggest that the caloric requirement for weight gain during refeeding is not predicted by the patient's anxiety, exercise or smoking habits. The standard methods of estimating caloric requirements for refeeding remain indirect calorimetry and previous history.

Factors associated with the increase in resting energy expenditure during refeeding in malnourished anorexia nervosa patients

BACKGROUND

In malnourished anorexia nervosa (AN) patients, body-weight gain during refeeding is slowed by an increase in resting energy expenditure (REE).

OBJECTIVE

The objective of the study was to identify factors associated with the increase in REE during refeeding.

DESIGN

Before and 8, 30, and 45 d after the beginning of refeeding, REE was studied by indirect calorimetry in 87 female AN patients [x +/- SD age: 23.4 +/- 7.9 y; body mass index (in kg/m2) 13.2 +/- 1.3]. Energy intake, body composition (by bioelectrical impedance analysis), physical activity, smoking behavior, abdominal pain, anxiety, depressive mood, serum thyrotropin and thyroid hormone, and urinary catecholamines were measured. REE was also evaluated in 18 patients after 1 y of recovery.

RESULTS

By day 8, REE increased from 3.84 +/- 0.6 to 4.36 +/- 0.59 MJ/d (P < 0.01). This increase (13.4%) was significantly (P <0.01) greater than that expected on the basis of the increase in fat-free mass (FFM; 1.6%). Thereafter, the ratio of REE to FFM remained high and, in multivariate analysis, was significantly related to 4 factors: energy intake (P <0.01), anxiety (P <0.01), abdominal pain (P <0.05), and depressive mood (P <0.05). The ratio also increased significantly with physical activity (P <0.01) and cigarette smoking (P <0.02). This rise in REE leveled off after recovery from AN.

CONCLUSION

In AN patients, the rise in REE observed during refeeding was independently linked to anxiety level, abdominal pain, physical activity, and cigarette smoking, and it contributed to resistance to weight gain.

Resting energy expenditure and plasma leptin levels in adolescent girls with anorexia nervosa

OBJECTIVE

Our aim was to examine the relationship between resting energy expenditure (REE) and circulating leptin levels during long-term refeeding in adolescent girls with anorexia nervosa (AN).

METHOD

We measured REE, the plasma leptin level, the free T(3) level, body surface area (BSA), and dietary energy intake in AN adolescents before and 8 weeks after refeeding therapy.

RESULTS

All parameters in AN subjects before the refeeding therapy were significantly lower than those in AN subjects after the therapy and in the controls. There were no significant differences in REE and BSA between posttherapy AN subjects and controls, but plasma leptin levels in the posttherapy AN subjects were still significantly lower than those in the controls. Significant correlations between REE and BSA were detected in the AN subjects both before and after the refeeding therapy, but REE did not correlate significantly with plasma leptin level in either of the AN groups.

DISCUSSION

Our results suggest that the REE in AN subjects after long-term refeeding therapy is not associated with the changes in plasma leptin levels but with BSA.

Anorexia nervosa medical issues

Anorexia nervosa is an increasingly common chronic psychiatric disorder with a multitude of medical complications. Most of these complications are reversible if there is timely restoration of body weight. A few of them, particularly osteoporosis, refeeding complications, and cardiac arrhythmia, are potentially much more serious. In the end, a multidisciplinary team approach with input from a primary care provider who is familiar with these medical sequelae, together with psychiatric and dietary expertise, can effectuate a successful outcome.

Research on energy expenditure in individuals with eating disorders: a review

OBJECTIVE

This study reviews the published research on energy expenditure in individuals with anorexia nervosa (AN), bulimia nervosa (BN), and binge eating disorder (BED).

METHOD

Individual studies are reviewed and their results summarized.

RESULTS

The most consistent finding is a reduction in resting energy expenditure (REE) in patients with AN, which increases with increased energy intake and body weight. Data regarding BN are inconsistent. Three available studies in subjects with BED have not found evidence of changes in energy expenditure corrected for lean body mass compared with obese non-binge eaters.

DISCUSSION

The ability to measure REE reliably and cost-effectively may aid in the refeeding of patients with AN in whom REE is reduced. Changes in individuals with BN and BED have yet to be consistently identified.

Research on energy expenditure in individuals with eating disorders: a review

OBJECTIVE

This study reviews the published research on energy expenditure in individuals with anorexia nervosa (AN), bulimia nervosa (BN), and binge eating disorder (BED).

METHOD

Individual studies are reviewed and their results summarized.

RESULTS

The most consistent finding is evidence of reduction in resting energy expenditure (REE) in patients with AN, which increases with increased energy intake and body weight. Data regarding BN are inconsistent. Three available studies in subjects with BED have not found evidence of changes in energy expenditure corrected for lean body mass compared with obese non-binge eaters.

DISCUSSION

The ability to reliably and cost-effectively measure REE may aid in the refeeding of patients with AN where REE is reduced. Changes in BN and BED subjects have yet to be identified consistently.