You know it’s fattening, but now the hard numbers — 490 calories — may force you to rethink buying that Big Mac in Britain.

About 1,200 McDonald’s restaurants in the U.K. will this week begin displaying the calorie count of each food and drink item on their wall-mounted menu boards, as part of a government-led program to fight obesity and promote healthier eating, the chain said Sunday.

McDonald’s already puts calorie information on its Web site and the back of its tray liners, but this is the first time the figures will be displayed prominently in its restaurants outside the U.S.

The chain has similar calorie menu boards in New York City, which became the first in the U.S. to put a calorie-posting law in place in 2008.

McDonald’s begins showing calories on menus in UK – BostonHerald.com