T863 is an orally active, selective and potent DGAT1 (Acyl-CoA:diacylglycerol acyltransferase 1) inhibitor that interacts with the acyl-CoA binding site of DGAT1, and inhibits triacylglycerol synthesis in cells. T863 causes weight loss, reduction in serum and liver triglycerides, and improved insulin sensitivity in obese mice.