Between 2010 and 2016, the percentage of parents who purchased kids' meals and received healthier drinks remained about the same at 59-60 percent. And, from 2013 to 2016, the percentage of parents who purchased kids' meals with healthier sides actually declined from 67 percent in 2013 to 50 percent in 2016.
Also, parents report buying fast food for their children more often. In fact, 91 percent of parents surveyed in 2016 said they purchased a meal for their child at the four largest fast-food chains in the past week, compared to 79 percent in 2010.
"It appears that restaurants' voluntary policies as currently implemented are unlikely to substantially reduce children's fast-food consumption overall, or increase their consumption of healthy items," the study says.
The report doesn't really surprise researchers. Past studies conducted by Rudd have shown that fast food restaurants are following their own voluntary pledges inconsistently.
For example, at one McDonald's location, the cashier may automatically include soda with a kids' meal, at another location you might need to ask, and the same goes for french fries, the study found. While all chains removed the items listed in their pledges from their online menus, many still listed soda on kids' meal menus in the brick-and-mortar restaurants.
Still, the "health halo" of the healthy offering policies seems to resonate with parents. Nearly all parents surveyed in the latest Rudd study said they would purchase food for their children at that restaurant more frequently because of the healthy offerings. But Harris says while they may have health in mind when entering the restaurant, this doesn't always lead to healthy choices.
"The marketing of the healthy options available is getting people in the door, but it's unlikely they'll take the effort to ask if [the restaurant has] something healthier," says the study's lead author Dr. Jennifer L. Harris, the director of marketing initiatives at the Rudd Center.
Instead, Harris says, the best option for public health would be to automatically include the healthy options with the kids' meals. "If fast food restaurants start automatically giving patients healthy choices, that would be encouraging," she says.
Hillary Caron, a senior policy associate at the Center for Science in the Public Interest, says that the Rudd Center's study is particularly interesting because it demonstrates the power of defaults in consumer decision-making. That is, if the meal comes with fries unless you ask for apple slices instead, you're likely to get fries.
Some government officials have already taken this message to heart. Just last week, California became to first state to pass a healthy kids' meal policy when Governor Jerry Brown signed legislation that prohibits soda and other sugary drinks from being the designated beverages that come with kids' meals. Similar bills have passed in cities like Baltimore and Louisville, and have been proposed in New York City and D.C.
Harris says that the findings of the latest Rudd study indicate a need for such public policies. Voluntary and mandatory policies could work hand in hand, though, according to Caron.
"Both approaches reinforce each other," Caron writes in an email to NPR. Voluntary commitments from restaurants, she says, help make the case for state and local policies because they show that the changes are achievable. But state and local policies ensure that the principles apply to all restaurants, not just chains that propose voluntary health policies.
Still, Harris wants people to remember that even if the fast food offered at restaurants is billed as healthy, most fast food meals still consist of chicken nuggets, burgers, and fries.
"It's important to communicate that fast food meals are not healthy options," Harris says. "Replacing soda with milk or water doesn't make the meal healthy," she adds. "It's a small step, but in the right direction."