LEP and obesity due to melanocortin 4 receptor deficiency: A study of alcohol-dependent individuals found that those consuming the highest levels of alcohol had increased metabolism and decreased fat mass and leptin levels.60 Furthermore, high alcohol consumption can impair nutrient absorption.61 The many studies of obesity and alcohol consumption have indicated a complex relationship62 with reports of both negative and positive correlations between alcohol and BMI.63, 64 We also report a negative genetic correlation between alcohol consumption and leptin levels (rG=−0.26, s.e.=0.08).