"Gigantopithecus" is considered to have been a herbivore. Carbon-13 isotope analysis suggests consumption of C3 plants—such as fruits, leaves, and other forest plants—and "Gigantopithecus" was likely a generalist feeder. The robust mandible of "Gigantopithecus" indicates it was capable of resisting high strains while chewing through tough or hard foods. However, the same mandibular anatomy is typically seen in modern apes which primarily eat soft leaves (folivores) or seeds (granivores). "Gigantopithecus" teeth have a markedly lower rate of pitting (caused by eating small, hard objects) than orangutans, more similar to the rate seen in chimpanzees, which could indicate a similarly generalist diet.