Global food systems are no longer sustainable for health, the environment, animal biodiversity and wellbeing, culinary traditions, socioeconomics, or small farmers. The increasing massive consumption of animal foods has been identified as a major determinant of unsustainability. However, today, the increasing consumption of ultra-processed foods (UPFs) worldwide is also questioned. Up today, more than 40 epidemiological studies have shown that excess UPF consumption signficantly increase the risks of several chronic diseases and all-cause mortality. Concerning the other dimensions of sustainability, we attempted, based on the collection of scattered data from scientific literature, to build the interrelations between massive UPF consumption and impacts on food systems. For this, we first identified the main ingredients/additives present in UPFs and the agricultural practices involved in their provision to agro-industrials. Overall, UPF production is analysed regarding its impacts on the environment, biodiversity, animal wellbeing, and cultural and socio-economic dimensions. Our main conclusion is that UPFs are associated with intensive agriculture/livestock and threaten all dimensions of food system sustainability due to the combination of low-cost ingredients at purchase and increased consumption worldwide. However, plant-based UPFs do not produce the highest greenhouse gas emissions (GHGEs) compared to conventional meat and dairy products. In addition, only reducing energy-dense UPF consumption (associated with excess calorie intakes), without substitution, might substantially reduce GHGEs. Therefore, significant improvement in food system sustainability requires urgently encouraging limiting UPF consumption to the benefit of mildly processed foods, preferably seasonal, organic and local products, a recommendation that we formalized in the concept of the 3V-based diet for Végétal (Plant), Vrai (Real foods), Varié (Varied, preferably organic, local and seasonal - when possible).