Despite its taxonomic classification as a carnivore, the giant panda's diet is primarily herbivorous, consisting almost exclusively of bamboo. However, the giant panda still has the digestive system of a carnivore, as well as carnivore-specific genes, so a diet of strictly bamboo gives the bear little energy and little protein. Because bamboo is so low in nutrition, pandas spend at least 12 hours each day eating and must keep their digestive tract full.

Pandas eat as much as 84 pounds (38 kilograms) of it each day. The limited energy input imposed on it by its diet has also affected the panda's behavior. The giant panda tends to limit its social interactions and lives a relatively sedentary life to limit its energy expenditures.