After years of delay, an Affordable Care  (ACA) Act rule requiring chain restaurants to label the calories in each item on their menu — and to provide sodium and other nutritional data on request — goes in effect today, May 7.

Though some large restaurant chains have been posting calorie counts for years, and while some states are already enforcing a similar mandate, the rule’s implementation may still take a while, as the FDA (Food and Drug Administration) says it will educate rather than enforce for the first year of the mandate.

FDA Commissioner Scott Gottlieb, M.D., an early critic of the ACA, nonetheless likes the rule. “This is a meaningful, incremental step in addressing” the country’s obesity epidemic, he says.

A statement by Gottlieb on the FDA website says of the rule:

Consumers walking into eating establishments covered under the rule will know how many calories are in the foods they may want to order. This includes establishments that are chains with 20 or more locations doing business under the same name that offer substantially the same menu items consisting of restaurant-type foods. Consumers can also ask these establishments for additional nutritional information — provided, for example, as a booklet, handout or in electronic form — that includes the amount of sodium, fiber, sugars, total carbohydrates, saturated fat and protein for any standard menu item.

Gottlieb, speaking more informally during an interview, said he frequently uses a restaurant’s calorie information on signs when ordering food. “I admittedly occasionally go to fast-food restaurants and take into consideration the calories,” he said. “I used to go to McDonald’s time to time to order an Egg McMuffin, but now I go for the Egg White Delight.”

According to McDonald’s, an Egg McMuffin is 300 calories while the Egg White Delight is 280 calories.

The National Restaurant Association is in favor of the rule, but largely to avoid a mish-mash of competing rules in the 50 states. The National Association of Convenience Stores (which also must post calorie counts) is less enthusiastic, but happy the FDA will take a year to bring everyone on board.

The FDA finalized its menu-labeling rule in 2013 but repeatedly delayed implementation to soothe over industry resistance.