Scan the shelves at your grocery store and you're sure to see 'em: food labels crying out "Fat-free," "Natural" and "Healthy."

They're designed to appeal to the health-conscious shopper.

But how can you really tell which foods are good for you, and which ones aren't?

Consider: the growing list of foods that have been emancipated from the do-not-eat list (think eggs) and the ones once deemed healthy that have fallen from grace (think granola).

It's enough to make a grocery shopper give up and head straight for the Twinkies aisle.

What's causing all the confusion?

Whole-grain bread

"Our views of what is considered healthy are changing based on new research we're getting," said Sharon Lehrman, a registered dietitian based in St. Louis Park who also is past president of the Minnesota Academy of Nutrition and Dietetics. "We used to tell everyone to eat low-fat. Period. Now we know that, really, it's the type of fats that are more important [than the total amount of fat]. The type of fat found in fish and avocados and nuts is healthy fat."

In response to this new information, groups like the U.S. Food and Drug Administration (FDA) are changing their views about everything from fat to sugar to cholesterol.

The FDA is in the process of redefining its standard for determining which foods can use the term "healthy" in marketing. The agency is asking for public input in coming up with a new definition, which will affect both nutrition labels on packaged foods and claims such as "healthy" and "good source of" often used on the front of food products.

To offer input, go to: regulations.gov and search under docket folder FDA-2016-D-2335.

You can thank the creators of Kind bars for the FDA's makeover of the "healthy" tag. Last year, the agency told the company that it could not use the term "healthy" on labels for some of its bars — the ones packed with nuts — because they exceeded the FDA's low-fat standard for "healthy." Fans of Kind bars then launched a petition drive to challenge the FDA's definition of what makes a food worthy of the label.

But some nutritionists say the problem actually may lie in using the word "healthy" in the first place. Any food can become healthful or unhealthful, depending on the amount you consume and how you prepare it, they argue.

Labeling something as a "health food" is oversimplistic and can become problematic, said Joanne Slavin, a food science and nutrition professor at the University of Minnesota.

"We never want to green-light [foods] in the U.S. because then people overdo it," she said. "That's the hard thing about food. We want to know whether we should eat this, and not that. Any individual food, you can interpret it in different ways."

Rather than offering people a silver bullet food, a better approach is to tell them to stick to the basics.

"Eat whole real foods. And less processed foods. And that actually is a simple message," Lehrman said.

Allie Shah • 612-673-4488