CHICAGO — Eating ham has never been more expensive than this year, partly because U.S. pigs are too fat.

Hogs in the U.S. weigh the most ever after farmers fed them longer to make up for losses caused by a virus that killed millions of piglets. While heavier hogs means more pork per animal, their hind legs exceed the size used for producing the 7-pound spiral-cut, half hams that are the most popular for family meals during year-end holidays.

Half of annual ham consumption by Americans occurs at Thanksgiving and Christmas dinners, and retail prices through September were up 24 percent this year to a record $3.389 a pound, the most recent government data show. The increase was fueled by the virus, which shrank the domestic herd and reduced the number of hogs slaughtered this year by 5.2 percent, boosting costs for meat buyers including Noodles & Co.

“This year has been a struggle for people that sell half hams because heavier hogs are coming to market,” Brian Mariuz, chief financial officer of HoneyBaked Ham Co.’s Michigan division, said by telephone from Troy, Michigan. The unit runs 74 of HoneyBaked’s more than 400 U.S. stores. “Seven-pound hams are in the highest demand and in the lowest supply.”

Meat processors slaughtered 92.09 million hogs this year through Nov. 15, down from 97.17 million in the same period a year earlier, after outbreaks of the deadly porcine epidemic diarrhea virus shrank domestic herds, U.S. Department of Agriculture data show. Even with hogs weighing a record 215.5 pounds each on average, pork output through September was down 1.2 percent to 16.71 billion pounds.

Pork’s price gains have contributed to higher meat costs, which the government forecasts will rise more than any other food group this year. The Consumer Price Index for meat, poultry, fish and eggs increased 9.4 percent in the year through September.

Around the holidays, U.S. consumers favor spiral-cut half hams, created by slicing the meat in one continuous coil around the bone, according to Urner Barry, a food-industry publisher in Bayville, New Jersey. A typical light ham weighs 17 pounds to 20 pounds and yields two half hams. The wholesale price of that cut more than doubled this year, USDA data show. HoneyBaked’s hams fetch $7.59 a pound this year, up 30 cents from a year ago, while the cost is up 50 cents, CFO Mariuz said.