Is the experimental evidence on ultra-processed food and obesity reliable?

Public health experts have issued widespread calls to target ultra-processed foods (UPF) in nutrition policy to prevent obesity and other diet-related chronic diseases. Several short-term crossover feeding studies have examined the effects of UPF consumption on energy intake and body weight, but their findings remain inconclusive, largely due to methodological limitations and imprecision in the Nova classification used to define UPF exposure. Long-term data demonstrating the effectiveness of reducing UPF intake are lacking. Consequently, the available evidence does not establish a causal role of UPF consumption in obesity. Additional research is needed to determine whether UPF, as defined by Nova, exerts effects on energy intake and body weight beyond those attributable to established dietary factors such as energy density and nutrient composition.