The giant pandas energy budget is so finely balanced that even a short regular walk can mean the difference between survival and death. For example, a hypothetical panda weighing 100kg has a basal metabolic rate (BMR) 2214 kilocalories. To indulge in the normal panda activities of foraging, defaecating, and drinking (though not for social interactions, territorial behaviour or other social activities) cost the panda approximately an extra 40 percent of its BMR. When such activities are taken into account, and a little more added for growth and reproduction, the total average energy requirement for an adult panda is at least 3500 4000 kilocalories a day. The giant pandas average daily intake of energy from bamboo to be between 4300 5500 kilocalories. The figures would be lower for those animals unable to feed on the more nutritious umbrella bamboo shoots during the spring. If we take the higher energy requirement figure (4000 kilocalories) and the lower intake figure (4300 kilocalories) it is easy to see how finely balanced the species is between life and death.
Due to this reason, giant pandas got to be spend their day and at the same time contrive to balance the energy budget. Behaviours such as locomotion, territoriality, courtship and mating all deplete energy reserves. Even so mundane an activity as defaecation requires energy, and the panda must allot no more than is necessary to each of these behaviours if it is to survive on its chosen diet.