In the Tang Dynasty, the famous doctor Sun Si-miao said that, when a person is sick, the doctor should first regulate the patient's diet and lifestyle. In most cases, these changes alone are enough to effect a cure over time. Sun Si-miao said that only if changes in diet and lifestyle are not enough should the doctor administer other interventions, such as internal medicine and acupuncture. Although most patients coming for professional TCM treatment today do need internal medicine and/or acupuncture as well as changes in their diet and lifestyle to effect a more rapid cure, it is most definitely my experience that without appropriate changes in diet and lifestyle, herbs and acupuncture do not achieve their full and lasting effect.
Form & Function
There are four basic foundations of achieving and maintaining good health. These are diet, exercise, adequate rest and relaxation, and a good mental attitude. Chinese medical theory is based on yin and yang. In terms of medicine, yin means substance and yang means function. This is similar to the Western medical dichotomy between form and function. Form and function are interdependent. Substance or form is both the material, anatomical basis of function and its fuel. Function, on the other hand, activates and motivates form and also repairs, builds, and maintains it.
We can liken the human organism to a candle. A candle's function is to burn and, therefore, shed light. The flame of the candle is dependent upon its form. At the same time, the candle's form, its wick and wax, is the fuel for the candle's function. The human organism is very similar to a candle in that our various activities and consciousness are dependent upon our form, our physical body. Our functional activities are a product of consuming and transforming or metabolizing this substance. When we are young, we generate more substance than we consume and thus we are able to grow, repair, and keep our bodies youthful in shape and appearance. However, past a certain age, due to a decline in our bodily organs' efficiency, we no longer produce an excess of fuel or substance and so we begin to consume our own form. When we have consumed all our yin substance, our organism no longer has sufficient fuel for function and so ceases or dies.
Unlike the candle which is endowed with a finite, unreplenishable form at the moment of its making, we humans are capable of taking in new form or substance. We do this by breathing, eating, and drinking. It is eating and drinking which provide us with the substance which fuels our day to day activities and which is transformed into our body's material basis. Therefore, from the point of view of morphology or yin substance, we most definitely are what we eat, drink, and breathe.
Exercise is a form of function. It is activity. In relationship to diet, exercise is yang to diet's yin. Exercise keeps function functioning at peak efficiency. However, in Chinese medicine, exercise and rest/relaxation are seen as the yin/yang aspects of a single issue. If we are too active, i.e., hyperfunctional, we consume too much fuel or substance. Therefore, rest and relaxation are the flip side of the coin of activity. Functional activities should be moderate -- not too much and not too little. If there is too little exercise, form or material substance is not adequately consumed and transformed and starts to accumulate and gunk up the works. If there is too little rest, hyperactivity, be that physical, mental, or emotional, consumes too much substance and overheats the organism leading to burnout. This means that diet on the one hand must be balanced by adequate activity and rest/relaxation on the other.