Professor Giles Yeo wants you to stop fretting about your supermarket loaf and whether it could be classed as ultra processed food (UPF). The definition of UPF as something that is made through industrial processes and contains ingredients not normally seen in the average kitchen – such as modified starch or emulsifiers – is too vague to be useful, according to the professor of molecular neuroendocrinology, who will be speaking at the Cambridge Festival this month. Instead he wants to ensure people who are less well off, who are most likely to have to buy processed foods because they are cheap…