The research was conducted by the University of Bristol’s Nutrition and Behaviour Group and has been published in the journal Appetite.
It supports the theory that humans are programmed to learn to like foods with more equal amounts of carbohydrate and fat.
Researchers wanted to test the largely untested assumptions that food energy density (calories per gram), level of processing and carbohydrate-to-fat ratio are key factors influencing how much people like a food and desire it.
For the experiment, which involved 224 adult volunteers, participants were presented with colour images of between 24 and 32 familiar foods, which varied in energy density, level of processing and carbohydrate-to-fat ratio. There were 52 different foods in total, including avocado, grapes, cashew nuts, king prawns, olives, blueberry muffin, crispbread, pepperoni sausage and ice cream.
The participants then had to rate the food in order of pleasantness, desire to eat, sweetness and saltiness. The results found that on average UPFs were not seen as more pleasant or desirable than processed or unprocessed foods.
However, foods that combined more equal amounts of carbohydrate and fat, were more liked and desired than foods containing the same number of calories mostly as carbohydrate, or mostly as fat.
Professor Peter Rogers, the study’s lead author, said: “Our results challenge the assumption that ultra-processed foods are hyperpalatable, and it seems odd that this has not been directly tested before.
“However, whilst 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.
“The results for sweetness and saltiness, are consistent with our innate liking for sweetness and saltiness. And the results for carbohydrate-to-fat ratio and fibre might be related to another important characteristic that determines food liking.
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