Almost 60% of the caloric intake of the average American diet is coming from ultra-processed foods, according to a 2017 paper published in the journal Population Health Metrics — and that's concerning to health experts.

"Ultra-processed foods contain ingredients that we generally wouldn't find in our kitchen, and they often contain high amounts of sugar and salt," says Jinan Banna, registered dietitian and professor of nutrition at the University of Hawaii.

"They may also contain additives, and they often are stripped of their nutritional values. So they may have very little vitamins and minerals [and] fiber."

Eating ultra-processed foods often can lead to a higher risk of developing health conditions like dementia, type 2 diabetes and heart disease, according to doctors in the American Medical Association.

That's why Banna limits her consumption of ultra-processed foods and encourages you to do the same. Here's the highly processed food that she never consumes.

'I would never consume soda,' dietitian says

"Some [ultra-processed foods] I would never consume, such as soda," Banna tells CNBC Make It.

"Soda doesn't have any nutritional value other than just calories in the form of sugar. So they're empty calories, which don't give us any of the nutrients that we need."

When you drink soda, it is digested very quickly and can cause you to feel hungry, she adds, which can lead you to eat more food than you planned to.

Instead of soda, Banna opts for different types of tea and water, still or sparkling.

"Sometimes I drink a cold hibiscus tea. Plain water, of course, is a great alternative," she says. "Even coffee can be an option, of course, consumed in moderation."

Diet soda and other ultra-processed drinks are the processed foods Americans consume the most, recent study shows

A recent preliminary study that was presented last week at a meeting held annually for the American Society for Nutrition took a close look at dietary data collected in 1995 from more than 500,000 Americans between the ages of 50 and 71. The data was used to determine if there were connections between dietary choices and mortality rates over the span of almost 30 years.

Out of 124 foods, ultra-processed drinks was the No. 1 food that people who had the highest intake of ultra-processed foods consumed.

"Diet soft drinks were the key contributor to ultra-processed food consumption. The second one was sugary soft drinks," the study's lead author Erikka Loftfield told CNN.

Beverages make up a significant portion of dietary intake. So, these types of drinks — like diet sodas and energy drinks — are the processed food that people seem to consume more than others, Loftfield said.

The study also found that the lifespans of those who eat a diet high in ultra-processed foods may be shortened by over 10%, according to CNN.

Use the 5/20 rule when reading nutrition labels

As a rule of thumb, Banna recommends using the 5/20 method when checking the nutrition labels on the foods you eat.

"You can use the daily value," she says. "That's an easy way to know whether the food is generally high or low in a particular nutrient."

Check the daily value percentages of specific nutrients like sodium, sugars or saturated fat, Banna suggests.

"The idea is, if [it's] 5% or less, then the food is generally low in that particular nutrient. If 20% or more, you can consider the food high [in the nutrient]," she says.

"So that's just a quick way to glance at the label and know if a food contains a little bit or a lot."

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