Ultra-processed foods are often high in fat and sugar In the past few years, there has been a growing clamour from scientists, doctors and the media about ultra-processed foods (UPFs). Some have warned that the trend towards more and more processed food in our diet is mainly responsible for the huge burden of chronic diseases in the modern world. But what are UPFs, what makes them bad for you, and how worried should you be? The first question is surprisingly difficult to answer.