Binge eating behaviour, appetite related hormones and the effect of short term glp-1 analogue therapy In obese subjects

Abstract

Obesity is a significant health problem, the incidence of which is rising at an alarming rate. A subset of obese individuals has been shown to have binge eating behavior (BEB), and they often do less well in weight loss therapy and have higher relapse rates. A salient feature of binge eating is the loss of control during an eating session, both in amount and duration. In this respect, numerous appetite hormones have been discovered and studied, among others include ghrelin (orexigenic-appetite stimulating), leptin (anorexic-appetite inhibiting), neuropeptide Y (orexigenic), glucagon-like peptide- 1(satiety signal), and insulin (anorexic). These hormones are involved in a complex signalling pathway in the brain which affects satiety and eating patterns. Determining the specific influence of these hormones on BEB among obese subjects is therefore vital. However, data on these are scarce.The objectives of this research are to investigate whether obese binge eaters have abnormalities in appetite hormones, binge eating is linked to stress and whether a novel treatment can reduce binge eating. The first part of this research is the validation of the binge eating questionnaire in the national language as a screening tool to diagnose BEB. It compared the Malay version of Binge Eating Scale (BES) questionnaire to the Structured Clinical Interview for the DSM-IV patient version (SCID-I/P), the gold standard for the diagnosis of binge eating. Based on BES scores, the eating behaviour is graded into three categories: scores ≤ 17 as absent, 18- 26 as moderate and ≥27 as severe. The Malay BES was found to have a sensitivity of 84.6%, specificity of 94%, positive predictive value of 81.8%, negative predictive value of 95.7% and Cronbach alpha=0.89. The validated BES was used subsequently in this study to differentiate those with BEB from those without. This research then studied the appetite hormones, ghrelin, leptin, NPY, GLP-1 and insulin and stress hormone, cortisol to detect any significant abnormalities in those with BEB in comparison to controls. A standardised test meal was conducted among 65 obese adults, with and without BEB. Hormones were measured at fasting and at multiple time points postprandially. There was a significant lower hormones ghrelin (p=0.023), GLP-1 (p=0.047) and insulin (p=0.016) levels among those with BEB. The study revealed no significant difference in the hormones neuropeptide Y and leptin, p= NS. Among those with BEB, a significant relation was found between cortisol and BES score: r=0.33 (p=0.027). There was a strong relationship between stress and the severity of binge eating suggesting an element of stress in modulating BEB. The final part of the research explored a novel treatment, GLP-1 analogue in treating binge eating. Fourty-four obese participants with BEB were randomised to treatment (liraglutide, diet and exercise) and control (diet and exercise) groups. After 12 weeks, the treatment group showed significantly greater reductions in BES score (p=0.036) compared to control. In addition, reductions in weight, body mass index, systolic blood pressure, waist circumference, fasting glucose and total cholesterol were observed (p<0.05). There was also significant increase in ghrelin and insulin, and a decrease in leptin, and postprandial glucose (p<0.05). The results suggested in obese individuals with BEB, short term pharmacotherapy with GLP-1 analogue could potentially provide the impetus to improve their binge behavior thus leading to long term control in weight.