Looking for a comprehensive book on the Digestive System

Hi All,

I'm not sure this is the right place, but I figured some people here might have a recommendation or two.

I want to study about the digestive system, so I would like recommendations on the best book to get. Specifically, I want to understand what creates the differences in digestive system attributes between patients, e.g. digestion speed, satiation, gastric emptying speed etc. I would also like the book to cover any tests that exist that can be done to analyze a patients digestive process, to determine factors influencing the efficiency of digestion.

Motivation is my desire to understand my own body. I have had digestive shortcomings my entire life (so it's obviously ultimately a genetic thing). These shortcomings have never risen to the level of 'pathology', so the many doctors I visited have always been uninterested and eager for me to leave their office. These digestive shortcomings have resulted in me having a severely malnourished appearance, hovering just above anorexic, generally low energy levels relative to my peers, and social problems in a dining setting (finishing even small amounts of food well after everybody else). This has greatly influenced my quality of life and put a hefty limit on my personal performance, especially in the social arena, so I am determined to know in detail the nature of this bodily shortcoming, such that I may possibly work out a way to ameliorate it.

So if anyone could recommend a good, comprehensive book on this topic, I would be very grateful. I have a good understanding of basic biology due to my high school studies, and I am happy to learn any other ground-work that would allow me to understand medical-level digestive biology.

Many thanks