For an area to be experiencing famine, at least 30 percent of children under 5 must be considered acutely malnourished by height and weight measures. Using the arm circumference method, the I.P.C. said, the accepted threshold dropped to 15 percent.

Parts of Gaza are officially experiencing a “man-made” famine, according to a Friday report by a United Nations-backed initiative, which added that the situation is expected to worsen after months of relentless conflict.