Economics has a term for what U.S. grocery prices have done in recent years. It's the rockets and feathers effect. Rockets, because the cost of food for eating at home shot up up after the coronavirus pandemic. Feathers, because prices fall slowly once they increase. That’s frustrating for Americans digesting a 33% jump in grocery prices since 2019 — the sharpest increase in 50 years. Food price inflation peaked nationwide in 2022, but it hasn’t reversed course. An acceleration during the Iran war prolonged the aggravation. A recent study by the consulting firm Bain & Co. and market research company NielsenIQ found that shoppers are buying fewer items at grocery stores.