How Many Calories in That Big Mac?

Tim Boyle | Bloomberg | Getty Images

Starting next week, consumers will know exactly how many calories they’re getting with that Big Mac (550 calories), fries (230) and milkshake (530).

McDonald’s will be providing calorie information ahead of reforms next year that will mandate calorie information.

Jan Fields, McDonald’s USA president, told CNBC’s “Squawk on the Street” that posting calorie information isn’t likely to cause a big shift in consumer behavior.

“People buy what they want to buy, but it helps them make better choices,” the executive said.

As far as sales, Fields expects the calorie information to have a positive impact. “People will feel better about eating at McDonald’s,” she said, noting an Egg McMuffin only has 300 calories. (Read More:Beer Milkshakes—the Latest Weapon in the Burger Wars.)

In recent years, the world’s biggest hamburger chain has diversified its menu with more healthful and cheaper offerings. Still, some analysts attribute the restaurant chain’s recent struggles to weakness in the global economy and rising cultural concerns about obesity. Intensified competition from rivals like Wendys and Burger King Worldwide are also pressuring McDonald's margins, analysts said.

Turning to the outlook for U.S. sales, Fields is optimistic. “We’ve got great new products coming out. We have our big burger coming out this fall, as well as the McRib and Monopoly promotions.”

The fast-food chain has also been able to manage increasing costs by focusing first on selling the right products and then we looking at how "we manage costs going forward whether it be from a pricing standpoint, hedging, and other input costs.”

-By Justin Menza, CNBC News Writer

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