A third of the food produced globally goes to waste, but leftovers are enjoying a revival, with leftovers cookbooks, leftovers influencers, even a leftovers-themed cooking show. Nancy Giles talks with food historian Eleanor Barnett about the value placed on food through the ages; and with Chris Morocco, food director of Bon Appétit and Epicurious, who delves into Giles' refrigerator to turn her leftovers into a whole new meal.