Ultra-processed foods are not more appealing to the hungry human eye, new research has found.
Junk food is viewed as no more appealing than less processed foods, scientists say, after they conducted a new study on the hunger and taste habits of Brits.
Researchers from the University of Bristol carried out a study comparing the taste perception of different food types to look into the long-held theory that the higher the level of processing done on foods in combination with the calorie level makes food more appetising to customers.
The theory was previously that calories and level of processing are "key factors" in influencing how much we like and desire the food on offer but new research has concluded that this may have been wrong the entire time.
The study’s lead author, Professor Peter Rogers, said the results his team had seen directly “challenge the assumption that ultra-processed foods are hyperpalatable".
A total of 224 adult volunteers took part in the study which saw participants presented with colour images of 24 to 32 familiar foods.
Pictures include the likes of avocado, grapes, cashew nuts, king prawns, olives, blueberry muffins, crispbread, pepperoni sausages and ice-cream and all varied in the levels of calories, nutrients, carbohydrate levels and level of processing.
Participants were then asked to rate the foods on a number of different factors while imagining tasting them, these were: taste pleasantness, the desire to eat and sweetness and saltiness level.
Results from the study, published in the journal Appetite, showed that, on average, ultra-processed foods were no more likely desired than processed or unprocessed foods.
They also found foods tasting more intense (mainly related to the level of sweetness and saltiness), were more liked and desired.
Professor Rogers said: "While ultra-processing didn’t reliably predict liking (palatability) in our study, food carbohydrate-to-fat ratio, food fibre content and taste intensity did – actually, together, these three characteristics accounted for more than half of the variability in liking across the foods we tested.
“Our suggestion is that humans are programmed to learn to like foods with more equal amounts of carbohydrate and fat, and lower amounts of fibre, because those foods are less filling per calorie. In other words, we value calories over fullness.”
The team behind the study, led by Bristol’s Nutrition and Behaviour Group, said the validity of their method was confirmed by, for example, finding a strong relationship between sweetness ratings and food sugar content.