FIGURE 1: A proposed pathway for how RYGB increases resting metabolic rate. 1 The rerouting of ingested food caused by RYGB may 2 downregulate jejunal CB1 receptors in L-cells, peripheral vagal afferent endings, and/or immune cells. This would then result in 3 the increased excitability of vagal afferent and splanchnic afferent nerve fibers which propagate their signals to 4 the central nervous system where they are processed. Splanchnic efferent neurons are in turn 5 stimulated to 6 region-specifically increase sympathetic tone and 7 induce browning of mesenteric white fat. The ultimate outcome is an increase in resting metabolic rate which drives weight loss maintenance and improvements in glycemic control.