Which is healthier: A bag of crisps or a kale salad? That is easy. Now which is healthier: A pizza made from scratch or one made from the same basic ingredients, with the same number of calories, pulled out of a box in the freezer?

Many people concerned with what they eat would instinctively say the former, perhaps citing a vague concern with “processed food”. Such food can often be delicious. (This columnist has a particular weakness for salty potato crisps.) And there is much to cheer about calories being cheap and abundant, when for most of human history they were neither. But as Chris van Tulleken’s new book, Ultra-Processed People, explains, that cheapness and abundance come at a cost.