There are many methods for dialectical diagnosis of traditional Chinese medicine. The most basic is the “eight-class syndrome differentiation”. The symptoms and signs of the patient are summarized from the aspects of yin and yang, appearance, cold and heat, and actual and actual conditions. A comprehensive judgment is obtained, either as a deficiency of yang or as a fever. It is either yin deficiency, or appearance and the like, and is associated with organs, meridians and other parts. There is a clear direction for medication or use of food, which can be adjusted accordingly. Medication treatment can be called "administration"; with food treatment, it may be called "feeding."
Such as a cold patient, is a form of evidence, but the cold as the main table for the cold, or cold, you should use ginger brown tea, onion ginger soup, Jiang sugar Suye drink, etc. to solve the table Xin Wen, divergent cold; the other hand, The heat is the main cause of wind-heat, when the use of sangju wolfberry drink, mint reed drink, cabbage mung bean drink, lotus leaf mint porridge and the like to Xin Liang solution, evacuation wind and heat.
Another example is some patients with high blood pressure, tuberculosis, chronic urinary tract infections, may have dizziness, tinnitus, backache, low fever, hand, foot and heart heat, insomnia, night sweats, red tongue, little moss, pulse breakdown embolism, diagnosed as Yin Huo-wang . Diet can be used snow soup, crystal sugar white tremella, pear porridge, etc. to nourishing Yin and reduce fire.
食疗之所以能够治疗疾病的理论基础。实际应用时，应如何判别某人之某病应服用何种食疗方呢？其所必须遵循的准则是“辨证论食”。
辨证，即是根据每个人的不同状况，综合地作出其疾病部位、证型诊断，以便有的放矢地给予相应药食处方。或此人基本是健康的，但在某一方面有虚亏倾向，则可以用食疗方法作相应调整。有病治病，无病防病。
中医辨证方法很多，最基本的是“八纲辨证”，即将病人的症状、体征从阴阳、表里、寒热、虚实八方面加以归纳，得出综合判断，或为阳虚，或为里热，或为阴虚，或为表实之类，并与脏腑、经络等部位联系起来，用药或用食就有了明确方向，可作相应调整。用药治疗可称“施治”；用食物治疗则无妨称为“施食”。
如一个感冒病人，属于表证，但以寒为主者为表寒，或称风寒，应选用生姜红糖茶、葱姜汤、姜糖苏叶饮等以辛温解表，发散风寒；反之，以热为主者为风热，当用桑菊豆豉饮、薄荷芦根饮、白菜绿豆饮、荷叶薄荷粥之类以辛凉解表，疏散风热。
又如在一些高血压、肺结核、慢性尿路感染等病人，可有头晕、耳鸣、腰酸、低热、手足心热、失眠、盗汗、舌红少苔、脉细数等症，诊断为阴虚火旺。食疗可用雪羹汤、冰糖清炖银耳、梨浆粥等以滋阴降火。