A new law requiring calorie counts on restaurant menus took effect in California on Saturday.

Under the law, restaurant chains with 20 or more outlets must include calorie counts for each food item on all menus, and on menu boards above the front counter.

The idea behind the law is to give consumers the information they need to order healthier options, if they want, health officials say.

The new state law does not include the menu in the drive-thru, but a new federal menu-posting law, which is expected to kick in around March, is supposed to include that, according to KPCC, a local radio station.

It's unclear whether the federal and state laws will match up, and which one would trump the other when both are in effect - a sort of fast-food war of a different kind, the report said.

The federal regulations will cover more restaurant chains and more items, including alcoholic beverages. U.S. officials have not said whether the calorie numbers on menu listings will have to be displayed differently.

The Los Angeles County restaurants that don't have them by New Year's Day won't be busted, however. The county has joined most others in the state that say they won't be enforcing the measure, passed two years ago, because federal guidelines will supersede the state regulation.

"These restaurant operators should not have to make up new menu boards and then make them again in March," said Angelo Bellomo, director of environmental health for Los Angeles County.