People often underestimate food waste because each unwanted item seems small: half a bowl of rice, a soft tomato or bread left after breakfast. Over a week, however, those small amounts form a clear pattern. The UN Environment Programme argues that measurement is essential because homes, restaurants and retailers need a reliable starting point before they can judge whether a solution works.
A household can begin with a simple diary. Record what is thrown away and why: too much was cooked, a date label was misunderstood, or a forgotten item spoiled. The goal is not to blame anyone. It is to identify repeated causes and test a practical response, such as planning portion sizes, freezing leftovers or placing older food at the front of the fridge.