Analyzing nutrition balance ?

[Externet]

Good day.   Perhaps will be better in other subforum, please move as deserved.

Food can be analyzed telling its amount of protein, carbohydrates, fats, minerals and all the components ingested and their weights.

If the body is not using/storing something by digestive, genetic or absortion defect, how is that to be determined ?  Can a blood/tissue test tell if a person has deficiency of -say potassium- or -say carbohydrates- , even with abundant enough consumption of those in food ?  And the reverse, can some analysis tell there is too much -say protein intake- ?

Is there a recommended percentage of the human body composition ?   When I used to work in aquaculture, the determining growth element was phosphorus.  If there was not enough of it in the food, growth was proportionally delayed/impaired no matter how much food was ingested.  That was determined by comparing the elements constituting the body of a shrimp and the elements found in their food 🤨

If there was enough phosphorus in food, the other elements absortion increased to reach the balance proportions.