CHICAGO — The battle over mandatory calorie disclosures on chain restaurant menus is heating up as public health advocates and the restaurant industry prepare to duke it out in Congress.

Last week, bills were introduced in the House and Senate that would force fast-food chains such as McDonald's to post calories on their menu boards, so you'll know at a glance not only how much your Big Mac costs, but also the 540 calories it packs.

Similar regulations, all aimed at curbing obesity, have been passed in recent years in several U.S. municipalities and two states, including in Massachusetts last week. The local rules have been adamantly opposed by the restaurant industry, which has fought back at the federal level.

Earlier this year, industry-backed bills were introduced in Congress that would require calorie disclosure, but not to the extent of the local and state rules or the rival calorie-disclosure bills just introduced on Capitol Hill.

Some public-health advocates criticize the industry-backed federal initiative as weak and dislike the fact that it would pre-empt stronger local rules. But the industry said a patchwork of local and state laws will confuse consumers and be costly to restaurant owners.

It's a top issue for the restaurant industry, which Saturday began its annual convention at Chicago's McCormick Place, one of the city's biggest business gatherings.

The Menu Education and Labeling Act, known as MEAL, was introduced in Congress last week. It would require restaurant chains with 20 or more stores to display calorie counts on their menu boards. The bill also would require printed menus at such chains to include calorie counts as well as information about trans fats, carbohydrates and sodium.

"The financial cost has been there (on the menu), but the health cost associated with your purchase has never been that easily accessible," said Mark Peysakhovich, senior director of advocacy in Illinois for the American Heart Association, which backs the MEAL bill along with the American Diabetes Association.

Scott Vinson, vice president at the National Council of Chain Restaurants, said the bill would be expensive and cumbersome for restaurant owners.

"The menu board is valuable real estate, and there's only so much information you can get on it," he said.