A recent study conducted by researchers in China revealed that giant pandas are as lethargic as the slow-moving sloths. Researchers said low levels of physical activity and thyroid hormones make them sluggish.

Researchers during their study studied three wild pandas at Foping Nature Reserve in Shaanxi province and five captive pandas at the Beijing Zoo.

The study published in the journal Science found that the daily energy expenditure of the pandas was just 38% as compared to animals of the similar size.

Lead author biologist Fuwen Wei of the Chinese Academy of Sciences' Institute of Zoology, Beijing, said that the daily energy expenditure values found in giant pandas are considerably lower than koalas.

Researchers during the study also found that the brains, livers and kidneys of the pandas were smaller than the organs seen in other bears.

Professor Wei said, “Giant pandas achieved this low metabolism through a suite of morphological, behavioral, physiological and genetic adaptations during their long evolutionary history. These reduced organ sizes likely contribute to their low energy demands”.

The study also showed that thyroid hormone levels in pandas were close to a fraction of the mammalian norm. Researchers also noted a gene variation in pandas matching the one seen in humans with underactive thyroids.

As per experts, thyroid hormones are essential for regulating body weight and energy. Low levels of thyroid hormones can lead to sluggishness.

The study found that the wild pandas rested for more than half a day and travelled around 20 meters per hour.