Effects of binge eating behavior on fuel oxidation and body composition

OBJECTIVE: To investigate energy expenditure and glucose metabolism after a standard oral glucose load (75 g) in 8 normal weight bulimic women and 8 normal weight control women and to evaluate the relative endocrine implication. DESIGN: Serum glucose and insulin were measured both in basal conditions and after the glucose load; a basal endocrine assessment and body composition was evaluated and glucose induced thermogenesis (GIT) was calculated during 300 min following the glucose load. RESULTS: Serum glucose levels were significantly lower in bulimics both in fasting and in post-prandial state. Insulin levels were similar in bulimic and control women before and after the glucose load. FSH, leptin and free urinary cortisol (FUC) were all within the normal ranges, but significantly lower in bulimic patients compared with controls (p < 0.001). Fat mass (FM) and Fat-free mass (FFM) were reduced in bulimic patients, even if they normalized after correction per body weight. Resting energy expenditure (REE) was similar in the two groups even after FFM normalization, while GIT was lower in bulimic patients and it was strongly related to free urinary chortisol. Glucose oxidation was higher in fasting state and post glucose load, while lipid oxidation was strongly reduced. CONCLUSION: An energy preservation mechanism seems to be the key element for normal-weight bulimic patients' metabolism, consisting in leptin levels and GIT reduction, and lipid oxidation inhibition