When my daughter was ten and a half months old, she qualified as “wasted,” which UNICEF describes as “the most immediate, visible and life-threatening form of malnutrition.” My wife and I had been trying hard to keep her weight up, and the classification felt like a pronouncement of failure. Her birth weight had been on the lower end of the scale but nothing alarming: six pounds, two ounces. She appeared as a dot on a chart in which colored curves traced optimal growth; fifteenth percentile, we ...