Why are giant pandas so lazy?

Professor Steve Steve informs us of an article Why are pandas so lazy? in Science Now. Professor Steve Steve takes exception to the claim that he is lazy. Yes, it is true that the giant panda’s daily energy expenditure is about 5 MJ: roughly one-third that of a dog and about the same as a three-toed sloth. It is also true that Professor Steve Steve moves slowly and basks a lot in the sun. Why? Because the giant panda is a carnivore that survives on a low-energy plant diet, which his body is ill-equipped to digest. To conserve energy, he maintains a low body temperature, and his organs, including his brain, are small.

Professor Steve Steve demurs. He claims that he is not lazy; he is simply ruminating.