Trying to eat healthy while dining out can be difficult. But beginning this month, it will become a lot easier to know how many calories you're consuming.

Restaurants, convenience stores, movie theaters, pizza delivery stores, grocery stores and even vending machines will be required to list calories on menus and/or boards. Additionally, sit-down and fast-food restaurants will have to provide additional nutritional information to diners who request it.

This change is part of the Affordable Care Act and applies to restaurants with more than 20 locations. Some chains, like Starbucks and McDonalds, have already posted their calorie counts in anticipation of the mandatory labeling even though the FDA hasn’t set a firm date for the requirement to begin.

FDA Commissioner Scott Gottlieb told CNN this change will improve public health. "This is a meaningful, incremental step in addressing" the country's obesity epidemic, said Gottlieb.

But will it make any difference?

According to a 2013 Carnegie Mellon study, having the information about calories doesn’t affect most people’s choices.

"There have been high hopes that menu labeling could be a key tool to help combat high obesity levels in this country, and many people do appreciate having that information available. Unfortunately, this approach doesn’t appear to be helping to reduce consumption very much, even when we give consumers what policymakers thought might help: some guidance for how many calories they should be eating," said the study’s lead author Julie Downs.

It's not really a surprise that most people don’t allow the calorie counts to influence their choices in restaurants. They ignore what’s in print, and they eat what they want.

Maybe, as I’ve speculated before, if people had to actually say the number of calories out loud when they order, it might make a difference. It’s easy to ignore the number on the menu, but if the Starbucks cashier couldn’t take your order without you saying, “I’ll have the 300 calorie Venti Caramel Macchiato,” perhaps you’d order the 180 calorie Tall instead.

As calorie counts become more prevalent on menus, do you think you’re ordering will be influenced by what’s in print or will you be able to push it to the back of your mind?

Editor's note: This article has been updated since it was originally published in July 2013.

Robin Shreeves ( @rshreeves ) focuses on food from a family perspective from her home base in New Jersey.

Restaurants now required to list calories
The law also affects convenience stores and vending machines.