people who take them are buying less food at walmart where today elladean nichols got her prescriptions groceries. >> i believe it. i'm buying less. >> reporter: she started taking ozempic after having two heart attacks and has lost 36 pounds since may. has it changed what you eat? >> 100%. the sweet stuff it literally turns my stomach. i used to have all the junk and sodas and all that. now it's -- it's half of what -- less than half of what it used to be. >> reporter: walmart has one of the most sophisticated systems for collecting data on its shoppers, and u.s. ceo john furner told bloomberg they've seen smaller checkouts from people taking these medications. "we do see a slight pullback in overall basket, less units, slightly less calories." does it surprise you that walmart's looking at that sort of data? >> i think every large retailer is looking at this data. they have the data through their loyalty programs. >> reporter: leo feler is a chief economist at a company that analyzes shopping receipts for millions of people. >> we use that data to help inform retailers, to help inform