For years, health advocates have urged the public to read the ingredients and ignore the marketing. For years, consumers have ignored the health advocates.

But lo! It looks as if they're finally listening.

Food purchases are less driven these days by what's written on the front of the box than what's listed as ingredients, said Andrew Mandzy, director of strategic insights at Nielsen. Some consumers aren't even reading so much as they are counting: About 61 percent said that the shorter the ingredients list, the healthier the product. Many are looking beyond the boxes themselves. In 2014, 48 percent of consumers went online for health information. In 2016, 68 percent did. Use of technology such as calorie-tracking apps is also up, Mandzy said.

"There's a shift in how people are thinking about 'better for you,' " he said. "People are looking for back-to-basics, simpler ingredients."

Health professionals are happy to see the shift. "The overall trend of a more-educated consumer is excellent," said Sharon Allison-Ottey, doctor, health educator and author of "Is That Fried Chicken Worth It?" "Just being aware of what you're eating leads you to eating less."

Front-of-package claims such as "low-fat" and "excellent source of vitamin C" are starting to lose their magical powers, Nielsen data show. Sales of items marked for their lower fat content are down 1.2 percent in dollar value over the past five years. For "fat-free," sales are down 2.7 percent. Items marked for their "vitamins and minerals" have seen a 0.8 percent decline in that period.

One claim, at least, seems to still work: "natural," an essentially unregulated and therefore meaningless term. So-called natural foods have included chicken nuggets, Cheetos and Gatorade. Sales for products bearing the label are up 4.2 percent.

But Nielsen also created a separate category with its own, narrower criteria. For that category, the market researchers took a closer look at ingredients, store placement (for example, is it in the "Natural" aisle?) and the rest of the brand. Anything USDA-certified organic, for example, was in, and anything with genetically modified organisms or artificial or synthetic ingredients was out. The growth in that narrower category was nearly triple the growth in the broader one, at 11.2 percent.