The mystery revolving around the muddled behavior of pandas is being studied for a long time now and it is attributed to bamboos.
It was recently found that pandas have an extremely slow metabolic rate, which is why they eat a low quality diet consisting mainly of bamboo sticks.
One of the evolution theories that were used to study pandas says that pandas are actually carnivores turned vegetarians. Since meat is easily digested in the guts of those animals that have short digestive tracts, pandas are designed to eat meat and not vegetables, according to Quartz.
Pandas are also designed with the gut of a lion, which is ideal for digesting meat and inefficient for digesting bamboo. This makes it harder and longer for their guts to digest the bamboos, making them lethargic and dopey, according to Daily Mail UK. They are known to eat at least 10 to 20 kg of bamboo per day, making their metabolism extremely slow.
Scientists used a methodology known as "the double labelled water method" in which they tried to assess the energy which the Pandas use from eating bamboos. This method measures the rate at which the animals are capable of eliminating stable isotopes from their bodies. This experiment was done on five pandas that were living in the Foping nature reserve.
It was also noted that Pandas consist of very low hormonal thyroid levels, T4 and T3. This greatly affects the genes which are involved in thyroid hormone synthesis. This also makes them to feel cold all the time as the low metabolic rate is not enough to warm them up.