If we look only at nutrition alone, it will lead us to the false believe that we should eat as much as we can to avoid nutritional deficiency. This is conventionally what most physicians think. When people learn about nutrition in medical school, it mostly focused on nutritional deficiency, especially protein deficiency. Nitrogen balance is under close-watch for in-patient setting to avoid wasting. However, this simplistic view overlooked the body’s ability to “deal” with food. It underestimates the burden required to break down, absorb, transport, store and dispose ingested food. It assumes that all food are similarly easy to digest.
For centuries, Chinese people and other traditional society have known that not all food are equally digestible. Some food may be very nutritious but they may also be very difficult to digest. Sometime we must apply the cost-benefit analysis to choose our food. Some food are so hard to digest that they are not worth eating.