It sounds straightforward enough, and you may have chosen to abide by this "food rule." But like many topics in nutrition, the advice is not as simple as it sounds.
Before you do a pantry or freezer overhaul, keep in mind that "processed" is a very general term.
Some processed foods serve as important players in filling nutrient gaps and contribute to the availability of a safe and convenient food supply. Others are, well, pretty much junk food.
The challenge lies in knowing which ones to include in your diet and which processed foods pose a problem.
Processed Foods 101
Processed foods include any food that has been deliberately changed before we consume it. "I think it is important that people understand, anytime you alter the food from its natural state, that is actually considered 'processed,' " said Kristi L. King, a senior registered dietitian at Texas Children's Hospital and a national spokeswoman for the Academy of Nutrition and Dietetics.
According to the International Food Information Council, processing can be as simple as freezing or drying food to preserve nutrients and freshness, or as complex as formulating a frozen meal with the optimal balance of nutrients and ingredients.
Minimally processed foods retain most of their inherent nutritional and physical properties. Examples of these include washed and cut fruits and vegetables, bagged salads and roasted nuts.
Those, along with foods processed to help preserve and enhance nutrients and freshness of foods at their peak -- canned tuna, beans and tomatoes, as well as frozen fruits and vegetables -- are healthful and offer important nutrients.
Other processed foods include sauces and dressings, as well as ready-to-eat breakfast cereal, crackers, nut butters, yogurt and milk fortified with calcium and vitamin D.
It's the more heavily processed foods, snacks and meals high in added sugars, sodium and unhealthy fats that are the "problem" processed foods, as consuming too many of them can lead to health problems. Also known as "ultra-processed" foods, they are formulations of salt, sugar, oils and fats, as well as flavors, colors and other additives.
"The problem with highly processed foods is, they are usually loaded with sodium for shelf stabilization, sugar for taste or added fats, including saturated and trans fats, for mouth feel," King said. Research has linked all of these ingredients to chronic health problems, including obesity, heart disease, diabetes, non-alcoholic fatty liver disease and some types of cancer, according to King.
"The cookies, chips, snack cakes that we all know and think of as 'processed foods' would be ones that are not so healthy for us, as well as sugar-sweetened beverages and highly processed meats such as sausage," she said.
How to cut back on highly processed foods
According to experts, the key to an overall healthy diet is to limit your intake of "ultra-processed" foods, which make up about 60% of our calories and contribute 90% of calories
from added sugars, while choosing healthier, unprocessed and minimally processed foods that offer a variety of nutrients.
And there are some relatively painless ways to do it.
1. Start slowly. "If you eat a significant amount of highly processed foods, try taking small steps toward a less processed diet," said Jackie Newgent, a registered dietitian, culinary nutritionist and author of "The All-Natural Diabetes Cookbook." "There's no need to go cold turkey today -- and often, if you slowly ease into a less-processed eating plan, your likelihood of continuing your wholesome new habits increases."
2. Supplement your meals with fresh foods. Try adding a banana or apple at breakfast or as a snack, or a vegetable at lunch. "Ultimately, half of your plate at lunch and dinner should be fruits and vegetables," King said. "Simply adding a freshly prepared salad to an otherwise not-so-fresh meal makes it better for your body ... and more enjoyable," Newgent said.
3. Fewer sugar-sweetened beverages, more water. If you get tired of water, King recommends carbonated water or adding fruit to water for flavor.
4. Stop adding salt to foods. "If you need an extra flavor boost, add garlic or pepper instead," King said.
5. Choose whole grains over processed grains. "Go with brown rice in place of white rice, whole-wheat pasta instead of 'white' pasta and whole-grain bread instead of 'white' bread. These swaps are nuttier-tasting and more filling, too," Newgent said.
6. Limit or avoid processed meats.
Meats such as bacon, ham, hot dogs and sausage have been linked to increased risk of colorectal cancer
7. Plan ahead. "If you find that you are reaching for the highly processed foods because they are convenient and you are in a hurry to get to your meeting or your kid to soccer practice, try planning out snacks on the weekend for the weekdays," King said. Set aside portions of trail mix, carrots and celery with hummus, Greek yogurts, and fruit with natural nut butters so they are ready to grab and go.
8. Use substitutes for highly processed snacks and foods. Instead of potato chips, try nonfat popcorn, which is whole grain and a good source of fiber and still gives the crunch you're looking for. "You can add a dash of chili powder or Parmesan cheese for flavor," King said. You can also replace sugar-sweetened cereal with unsweetened oatmeal and add fruit for flavor.
9. Make your own versions of traditionally processed foods. Consider homemade kale chips, granola and even salad dressings.
"Instead of bottled salad dressing that may contain preservatives your body doesn't need, whip up your own," Newgent said. "Simply whisk together three tablespoons of olive oil and one tablespoon vinegar of choice for an easy two-ingredient vinaigrette. Or add that oil and vinegar to a blender with a small handful of berries for a lovely fruity salad dressing."
10. Make healthier versions of frozen meals. "Try batch cooking on the weekend or a weeknight when you have time," King said. Consider a homemade mac and cheese with whole-wheat pasta and veggies or turkey burger patties with sautéed vegetables.
11. Don't be fooled by the advertising. If you see fat- or sugar-modified food, such as fat-free mayo or sugar-free yogurt, be wary. "These foods may have artificial ingredients -- such as the artificial colors yellow No. 6 or red No. 40 -- or other chemical additives, such as the artificial sweetener acesulfame potassium, making them more processed and potentially less healthful for you," Newgent said.
"Read the ingredient list on packaged foods, and look for a list that reads more like a recipe rather than a pseudo-science experiment," she added.