The Food and Drug Administration announced last week that it plans to weigh in on a question that has puzzled many supermarket shoppers wandering through aisle after aisle of colorfully packaged processed foods.

Which of these foods are really “healthy?”

The move by the FDA came as a result of a warning letter it sent in March 2015 to New York-based Kind LLC, maker of the self-described “healthy and tasty” snack bars.

It was this choice of words used to describe its products that landed the company in hot water with the regulatory agency.

Although Kind uses simple ingredients like fruit, nuts, and whole grains in the snack bars it’s been producing since 2004, the high fat content bumped the bars out of the FDA’s “healthy” category.

what is healthy food

Much of that fat was due to almonds and other nuts in the bars. Those same kinds of nuts are recommended by the government’s current MyPlate guidelines as part of a balanced diet.

The FDA’s shunning of high-fat packaged foods is a holdover from the 1990s when dietary fat was vilified. Saturated fats — found in animal products like red meat and butter — garnered most of the attention. But most fats, including plant-based ones, were swept up in this low-fat frenzy.

However, things may be changing for the food industry.

Kind LLC stopped using the phrase immediately, but it pushed back at the FDA’s decision. This included submitting a petition co-signed by 16 health and nutrition experts from Tufts, Harvard, and other leading institutions.

The petition asked the FDA to update its rules based on the latest nutrition research.

The FDA said it plans to seek input from experts and the public on a new definition of “healthy” for food labels. There is no timeline yet for this review.

Read More: New Dietary Guidelines: ‘All Food and Beverage Choices Matter’ »

How Do You Decide What’s Healthy?

So where does that leave you when you’re standing bewildered in the supermarket aisles?

One of the best places to start — even before you reach the supermarket — is the dietary guidelines the U.S. government puts out summarizing the latest nutrition research.

Creating these guidelines is no small undertaking.

“It’s very challenging,” Cheryl Achterberg, Ph.D., a professor of human nutrition and the dean of the College of Education and Human Ecology at The Ohio State University, told Healthline. “The idea is to evaluate the new evidence in the last five years. The volume is so huge, it’s unbelievable what happens in five years.”

Although there is a lot of nutrition research, not all of it is high quality. The gold standard of research — randomized, controlled clinical trials — takes a lot of effort and money.

Nutrition studies are also plagued by other challenges, such as knowing what people ate over long periods — often with them recalling their meals days or weeks later — or having people in a study faithfully stick to a diet that you prescribe for them.

But the government guidelines do emphasize the basics that many nutritionists would agree with — eat a variety of vegetables, whole fruits, whole grains, and lean protein sources including nuts and seeds. And limit your intake of saturated fats.

Read More: What the New Fat Guidelines Mean for You »

Back to the Supermarket Aisle

When you look at the labels on your favorite products, you will find a variety of information trying to tell you whether the food is healthy.

The Nutrition Facts panel and the ingredients list on the back are the best known.

But there are also marketing phrases on the labels, like the “healthy and tasty” phrase that Kind was using for its snack bars.

Food manufacturers want these types of catchphrases on their packages because they can create a warm, fuzzy feeling for consumers about the product — what’s known as a “health halo.”

“When [a product is] perceived as healthy, then we may feel comfortable consuming more of it or we don’t feel so guilty about it,” Eric VanEpps, Ph.D., a postdoctoral fellow in the Department of Medical Ethics and Health Policy at the University of Pennsylvania, told Healthline.

Products like salads and Subway sandwiches carry that kind of health halo.

On-label marketing, though, is not always the best way to decide which product is healthiest.

“My own personal opinion,” said Achterberg, “is that ‘healthy’ is not a very useful label at all because the meaning is ambiguous. There is a lot of individual variability.”

As the dietary guidelines remind us, a healthy diet is one that is balanced.

Even a food with a “healthy” label — like the Kind snack bars, which the FDA recently said could be labeled with that phrase again — needs to be coupled with other healthy foods to make a complete and nutritious diet.

“Even with something that anybody might think is healthy, if that’s all you ate or if you ate a very, very large amount of that, it might not be healthy for you,” said Achterberg.

New Food Label Systems

Researchers are testing other label systems to see if they can help consumers make better choices in the supermarket. Right now there are many different approaches, like stars or numbers representing a product’s overall “healthiness.”

Some of these seem to work.

A 2015 study in the Journal of Marketing Research found that when this type of system was used, consumers made healthier food choices.

“When you have a scoring system that applies across all of the products,” said VanEpps, “then you can use that scoring system to pick the relatively healthier thing.”

Ideally, the labels would work well in conjunction with the government’s dietary guidelines and each person’s personal preferences, medical restrictions, and cultural background.

But even those guidelines may need a little boost to make the nutritional information more consumer-friendly.

“Beyond the guidelines by themselves,” said Achterberg, “there’s room for different groups to create or translate that general info into more practical, hands-on educational materials that will work for different purposes.”

Read More: Why Is Nutrition Advice So Confusing? »