The causes of obesity include exogenous factors, dietary factors and weakened body constitution. The infantile zang organs are weak in function, and the spleen is constantly insufficient in function. The exogenous pathogenic dampness accumulates in the spleen. Again, because of the asthenia of the spleen, dampness originates from the inside. The external dampness in combination with the internal one transforms into phlegm, which accumulates in the skin and muscles, developing obesity; the infantile ignorance of controlling the diet and excessive intake of fat and sweet food impair the spleen qi, giving rise to strong stomach but weak spleen, bulimia. Due to the asthenia of the spleen, and internal dampness cannot be transformed and transported.

With the passing of time, the body will be full of fat, developing into obesity; or yang deficiency of the spleen and kidney due to congenital deficiency causes water and dampness not to be transformed. The accumulated water and dampness will develop into phlegm. Besides, due to yin deficiency of the body, the fire of deficiency type scorches body fluid into phlegm. The phlegm accumulates in the skin and muscles, developing into obesity.