Ccnventional conpartmental models for the study of human metabolism are of little value when intermediary pathways are complex. The validity is undermined by over-simplification, assumptions of exponentiality, and the use of questionable notions such as volume of distribution. An alternative to such models is described based on the circulatory system using semi-Markovian insights. The model requires only observables. Funds are required to support continuing study of the model and to complete its development into a working laboratory tool.