On Tuesday, the Food and Drug Administration released its rule for calorie counts on chain restaurants, the culmination of a years-long process mandated under the Affordable Care Act. The final rule is much tougher than the draft version, requiring movie theaters, pizza parlors and even grocery stores to include calorie counts on their products. Advocates are pleased with it—but will it actually lead to lower calorie consumption and lower rates of obesity? The evidence offers precious little proof that it will.

The premise of calorie counts on food items is obvious: If a person sees that the hamburger has 800 calories in it and the chicken only has 500, maybe that person will choose the chicken. Even slight changes in food choices can make a significant difference in health outcomes.

In 2013, researchers at the Robert Wood Johnson Foundation put together a literature review of studies on menu labeling, in order to understand public opinion on menu labeling and the effectiveness on calorie counts. The idea itself turns out to be pretty popular. In the United States, for instance, nearly three-quarters of Americans support menu labeling. After New York required labels in 2008, 84 percent of residents said they found the labels helpful. A majority of Americans also said they would choose lower-calorie food items if they had more information at their disposal—a possible sign that calorie counts could improve health.

But research also suggests that Americans are unlikely to change their behavior, even with the extra information about calories. “Four out of five controlled studies that compare restaurant patron choices in jurisdictions with and without menu labeling regulations before and shortly after menu labeling implementation have not found a relative reduction in calories purchased,” the researchers write.

The evidence itself isn’t definitive. One of the five studies showed a small decrease in calorie consumption and “the impact of food labeling is not uniform.” In some studies, women were more likely to reduce their calorie consumption than men were. And all of these studies used a limited timeframe—just six months. It’s possible that consumer behavior will show greater changes to calorie counts over a longer period.

“The bulk of studies to date have focused on purchases only, not consumption,” said Lisa Mancino, an agricultural economist at the United States Department of Agriculture, who co-authored a report in 2011 on how the ACA’s food labeling requirement would affect health. “It may be that while consumers are not likely to change what they purchase, they may change how much they purchase (although that’s doubtful). It’s also possible that consumers will be better able to compensate for a big meal away from home by eating fewer calories at other meals that day.”

At the very least, regulators may learn how to choose a label format that has a greater effect on consumer behavior.  “Providing calories, use of ‘healthy choice’ symbols, displaying total caloric intake needs, and presenting items in order of caloric content might have some effects on reducing calories purchased,” the researchers note. The calorie counts could force restaurants to offer lower-calorie food, for instance.

“I think it’s unrealistic to expect that putting calorie counts on menu items will influence choices among consumers who are not concerned about making healthier choices,” said Mancino. “So it’s unlikely that calorie counts will influence the majority of consumers directly. But they may influence what food choices are available by encouraging restaurants to offer some low calorie options. This could increase the supply of healthy, lower calorie options when eating away from home.”

That’s worth a shot.

This piece has been updated.