The decrease of ground temperature in winter is due to the downward and latent movement trend of Yang in nature. In winter, the movement trend of yang in human body is consistent with that in nature, so that the yang in human body is inhibited and declined, and it is hidden in the kidney. Among the five internal organs, the kidney is dominant in winter. Therefore, winter is the season of storing and nourishing kidneys.

Tonifying the kidney in winter conforms to the hidden trend of the decline of yang in nature and human body, and the substance for tonifying the kidney can be hidden in the kidney smoothly. If you tonify the kidney in spring, the substances that supplement the human body will go to the liver and are not easy to hide in the kidney. Therefore, the effect of replenishing different viscera in different seasons should be good. Four-season health care means nourishing liver in spring, heart in summer, lungs in autumn and kidneys in winter.

Eating mutton often in cold winter can replenish qi and deficiency, promote blood circulation and enhance the ability to keep out the cold. It can also increase digestive enzymes, protect the stomach wall and be easy to digest. So eating more mutton can improve the body's immunity. There is a folk saying that "if you want to live a long life, you should always eat mutton."

At the same time, eating black in winter also tonifies the kidney. Eat black, get ready to eat black. Chinese medicine believes that black corresponds to winter and kidney. Pay attention to eat more black food in winter, such as black beans, black sesame seeds, black rice, black fungus, mulberry and so on. You can eat some in moderation every day and stick to it. In addition, you can eat more yam, scallop, perch, chestnut, medlar, Polygonum multiflorum and so on.