It sounds like a mass conspiracy at first: food companies have figured out a way to manufacture foods that are just the right amount of sweet, salty or fatty — and now we can't stop eating them. Unfortunately, it's not that far from reality.

The term "hyper-palatable" foods (HPF) isn't necessarily new. In a 2009 interview with The New York Times, the former head of the Food and Drug Administration, Dr. David A. Kessler, describes how "conditioned overeating" is less a matter of willpower and more a biological challenge. It's not our fault junk food is so irresistible, explains Kessler, but rather that food companies "design food for irresistibility. It's been part of their business plans."

Scientists from the University of Kansas with a similar outlook to Kessler's recently published research in the journal Obesity that finally provides a quantitative definition of what constitutes an HPR. Though countless academic studies, documentaries and popular books have explored the rise of ultra-processed foods and what makes them so addictive, none has managed to define specific metrics for this class of tempting foods.

"Multiple documentaries have pointed out that food companies have very well-designed formulas for these types of foods to make them palatable and essentially enhance consumption," said lead author Tera Fazzino, assistant professor of psychology at the University of Kansas and associate director of the Cofrin Logan Center for Addiction Research and Treatment at KU's Life Span Institute.

"But these definitions are virtually unknown to the scientific community, which is a major limitation," continues Fazzino. "If there's no standardized definition, we can't compare across studies — we've just typically used descriptive definitions like 'sweets,' ‘desserts' and 'fast foods.' That type of descriptive definition isn't specific to the actual mechanisms by which the ingredients lead to this enhanced palatability. This has been a substantial limitation in the field I thought was important to try to address."

This new, quantitative definition of HPF was then applied to a government nutrition database to determine the prevalence of HPF in the U.S. food system. The results? Much of the food we eat in this country meet this criteria.

The aisle of overeating

Researchers at the University of Kansas found that 62% of foods in one government database met the criteria for being 'hyper-palatable.'. Thayne Tuason [CC by SA 4.0]/Wikimedia Commons

After analyzing 7,757 food items in the U.S. Department of Agriculture's Food and Nutrient Database for Dietary Studies, researchers found that 62% of foods in the database met the definition of hyper-palatability, including 49% of all items labeled as "low/reduced/no sugar, fat, sodium, and/or sugar." So even if you think you're making a healthy choice, you might be getting fooled.

"We essentially took all of the descriptive definitions of the foods from the literature — for example, Oreos or mac and cheese — and we entered these one by one into a nutrition program that is very careful in how it quantifies a food's ingredients," Fazzino said. "This nutrition software essentially provides in fine-grained detail a data set that specifies how many calories per serving are in this food, and how much fat, sodium, sugar, carbohydrates, fiber and all sorts of other things."

Researchers were also able to single out what tantalizing flavor combinations could result in hyper-palatability: combinations of fat and sodium (hot dogs, bacon); combinations of fat and simple sugars (ice cream, cookies); and combinations of carbohydrates and sodium (pretzels, chips).

"Essentially, we wanted to identify foods that appear to cluster together with what appeared to be like similar levels of at least two ingredients, because that's the theoretical basis for inducing the synergistic palatability effect," Fazzino said. "Through a visualization process, we were able to see there were essentially three types of foods that appeared to cluster together in terms of their ingredients."

These flavor combinations don't just happen by accident; food scientists spend a lot of time figuring out exactly what amount of sugar, salt and fat will make us reach what Kessler calls the "bliss point."

Besides knowing that HPF lurk in every aisle of the grocery store, these new definitions will aid researchers in their work on obesity and other diet-related health risks. These problematic foods could also help scientists understand the brain mechanisms that drive our tendency to overeat.

Looking at the many insidious ways HPF is integrated into our existing food system can also assist with future food policy. "We need more evidence — but eventually if research begins to support that these foods may be particularly problematic for society, I think that could warrant something like a food label saying 'this is hyperpalatable.'"