UPFs are the result of complex industrial processes, where sugar, fat, and/or salt and additives have been added. These products are generally characterized by a rather negative nutritional composition. They are thought to promote overconsumption through the effect of food properties (e.g. energy density, food texture, palatability) on for example satiation, satiety, and eating rate. Negative health effects have been reported in observational studies and the first RCT showed significant weight gain after a two-week intervention of following an ultra-processed diet. More research is needed to confirm causal effects, but for some UPF subgroups, the evidence is already stronger (e.g. processed meat and SSB). Studies investigating the environmental impact of UPFs are limited. Nevertheless, they suggest that a reduced consumption of UPF could contribute to the transition towards a more sustainable food system. In Belgium, the consumption of UPFs contributes to approximately 30% of the total energy intake. Many possible behavioral determinants linked to UPF consumption have been described: e.g. nutrition knowledge, cooking skills, consumers attitude
towards additives/processing/packaging, convenience, cost, availability, and food
marketing. It is recognized that the group of UPFs is very diverse in multiple aspects which makes
it difficult to make general conclusions based on solely the degree of processing. Therefore, it seems appropriate to conclude that the degree of processing should be considered as a criterium but not the only criterium when considering the health and environmental effects of food, e.g. for developing food based dietary guidelines. The consensus that unprocessed and minimally processed foods are preferred over UPFs is strong and can be put forward as a leading principle in food choice. For processed foods and UPFs the effect of the degree of processing and its effect on the nutritional value of foods should be considered (positive, neutral or negative). Even within the
group of UPFs consumers can be guided to make the better choice. To put this knowledge into practice, the behavioral determinants (competences, motives, and context) related to UPF consumption should be taken into account. Contextual determinants could be tackled by policy makers.