Biological process

negative regulation of UDP-glucose-glycogen glucosyltransferase activity, negative regulation of UDP-glucose:glycogen 4-alpha-D-glucosyltransferase activity, negative regulation of UDP-glycogen synthase activity, negative regulation of UDPG-glycogen synthetase activity, negative regulation of UDPG-glycogen transglucosylase activity, negative regulation of UDPglucose:glycogen 4-alpha-D-glucosyltransferase activity, negative regulation of glycogen (starch) synthetase activity, negative regulation of uridine diphosphoglucose-glycogen glucosyltransferase activity

Any process that stops, prevents or reduces the frequency, rate or extent of glycogen (starch) synthase activity.