Guijarro A et al. - The attenuated caloric intake, reduced food efficiency, and normalization of hormonal levels on day 28 post-RYGB were associated with significant down-regulation of endocannabinoids anandamide and 2-arachidonoylglycerol in muscle and liver, respectively. These results suggest a role for endocannabinoids in the mechanism of sustained weight loss and RYGB success, and may have implications for treatment of morbid obesity.