In September, McDonald’s broke with the restaurant industry pack by announcing it would immediately begin putting calorie labels on menus months ahead of a new federal health care law mandate that takes effect in in 2013.

But instead of following in the burger giant’s footsteps, metro Atlanta restaurants — including locally based eateries such as Chick-fil-A, Arby’s and Waffle House — have decided to wait for the mandate.

The reason, they say: uncertainty over which calories to count, where they should be listed and the cost associated with menu alterations.

“We simply do not want go ahead and make changes of what we ‘think’ will be required and then have to make a second change a few months later once we do know the specific requirements,” Chick-fil-A spokesman Mark Baldwin said.

Arby’s leaders agreed, saying they expect the Food & Drug Administration to set the guidelines sometime later this year.

“Until then there are still many details to be determined and limited guidance has been provided to date by the FDA,” said Jo Ann Herold, a spokeswoman for the roast beef giant.

The mandate, part of the Affordable Care Act, requires all chains with 20 or more outlets — from fast-food to fine dining — to list calories on menus, including an estimate of overall caloric intake on meal combinations such as a burger, fries and drink. The idea is to fight America’s obesity epidemic by making diners more aware of calories when eating out.

Waffle House, while reluctant to make systemwide changes ahead of the law, had no problems altering its menus at Nashville locations about 18 months ago, spokesman Pat Warner said.

The city’s government was considering requiring the labeling. Though the edict was pulled back because of the anticipated national effort, Waffle House has kept the new listings, which it just rolled into an updated menu.

“With that, we were able to work the kinks out before (the mandate) goes into effect everywhere,” Warner said.

Sodium and fat content are not required in the mandate, but diners can get them on request. Businesses whose primary purpose is not to sell food — such as airlines, theaters and bowling alleys, are exempt. A date for the mandate to take effect has not been issued.

Calorie labeling on menus is not new. New York City and California already require the practice and many restaurant chains list calories on websites.

While the McDonald’s move comes before the FDA has set final guidelines, the company has been experimenting with listing calories for a while in some markets, including Atlanta, company leaders said. In addition to menus, the chain has put calorie counts on tray liners and packaging.

“McDonald’s is very supportive of menu labeling,” said J.M. Owens, an Atlanta McDonald’s operator and former president of the Greater Atlanta McDonald’s Operators Association.

But critics say listing calorie counts will be a bigger challenge than most think. For instance, how you do fit the calorie counts of different toppings on a pizza on one menu, they ask? What about a loaded baked potato?

In addition, they argue that menu boards are already crowded and that listing calories will only make them more difficult to read.

Officials with Darden Restaurants, owner of the Red Lobster and Seasons 52 chains, worked with the FDA to create a universal system because of the varied interests, said spokesman Rich Jeffers.

“All we want to have is that consistency and predictability in our business model,” said Jeffers.

Peter Riggs said one of the biggest fears is that there could be more regulations to come.

“There’s a lot of reactionary behavior to fighting obesity,” said Riggs, vice president of brand development for Pita Pit, a pita chain with four Georgia locations. “This year it’s calories. But what if nobody changes their behavior? Will they come back and say now we want you to list fat grams to see if that sticks.”