Research Roundup

Evidence that carbohydrate-to-fat ratio and taste, but not energy density or NOVA level of processing, are determinants of food liking and food reward

30 January 2024

Overweight and obesity are commonly blamed on the ready accessibility of hyper-palatable foods. A virtual (online) study tested the common assumptions that food energy density, level of processing (NOVA categories), and carbohydrate-to-fat (CF) ratio are key determinants of food reward. 224 participants were randomised into one of three groups: energy density (32 foods), level of processing (24 foods), or CF ratio (24 foods). Foods were rated for taste pleasantness (liking), desire to eat (food reward), and sweetness, saltiness, and flavour intensity (for analysis averaged as taste intensity). Results show that there was not a positive relationship between liking or food reward and either energy density or level of processing. Foods combining more equal energy amounts of carbohydrate and fat (“combo foods”), and foods tasting more intense, scored higher on both liking and food reward.   

Of interest is that while ultra-processed foods were more rewarding and more liked than the combined category of unprocessed and minimally-processed foods, they were considered less rewarding than processed foods. Additionally, ultra-processed foods (which included strawberry yogurt, ice cream, doughnuts, crisps, pretzels, processed cheeses, and pepperoni sausage) were no more rewarding and liked than unprocessed foods (which included e.g. tomatoes, carrots, grapes, boiled egg, and avocado). The least liked and rewarding were minimally processed foods (which included king prawns, natural yogurt, sultanas, and dried apple slices). These results do not support the claim that ultra-processed (or ‘highly processed’) foods are hyper-palatable or at least they are no more palatable than commonly eaten unprocessed foods.  

A key limitation of this study is that it was virtual and relied on images of food.  

Reference: Rogers PJ et al. Evidence that carbohydrate-to-fat ratio and taste, but not energy density or NOVA level of processing, are determinants of food liking and food reward. Appetite. 2024,193 (1 Feb). https://doi.org/10.1016/j.appet.2023.107124