Metabolic dysfunction in anorexia nervosa

Context: Anorexia nervosa (AN) is an eating disorder characterized by self-induced energy deficit and low body weight with major consequences for most organ systems and a tendency towards self-perpetuation. Objectives: To compare metabolic responses to glucose and exercise in women hospitalized with AN (n = 10) before and after 6-weeks weight gain program and in lean healthy weight women (BMI < 22 kg/m²) (n = 7). Main outcomes: Weight, body composition, indirect calorimetry, and response of serum insulin, glucose, adiponectin and leptin to oral glucose (75 g) and to 30-min of cycling at 50 rpm. Results: Patients with AN had similar lean mass to controls, but had significantly less body fat. Adiponectin was 43% higher (p < 0.01) and leptin 47% lower in AN subjects versus controls (p = 0.04). In response to moderate exercise, fasting glucose increased in AN (p < 0.05), but was unchanged in controls. After glucose ingestion, a trend towards a greater increase in diet-induced thermogenesis was also observed in patients with AN (p = 0.07). Despite a further 6 weeks as in patients, weight was not significantly changed in AN. Similarly, glucose, insulin, leptin or adiponectin were not altered. Conclusions: AN patients appear metabolically healthy under resting conditions, but their responses to physiological stressors differed from those of controls. Potential impediments to weight gain should be further investigated to define mechanisms with a view to improving the effectiveness of nutritional management.