Two people go to a Chinese restaurant, order Chow Mein, but get Ptomaine poisoning. One manifests symptoms, the other does not.

Which one is actually sick?

The body may very well be getting rid of a poison when it manifests those unpleasant symptoms. That does not mean that it is sick. On the contrary, it may mean it is healthy. A body working properly may flush poisons from the system by vomiting and diarrhea. The person that did not experience these symptoms may have the poisons remain in his body longer causing more damage.

On the other hand, the person that did not experience symptoms may have such a good immune system that he was able to get rid of the poisons without having to experience any uncomfortable symptoms.

Since symptoms are a poor judge of health and how the body is working; and since we cannot always know if symptoms are good or bad; we do not use them as criteria for how often and where to adjust, or how the body is working.