These are the key homeostatic systems that determine your metabolic type. For example, your autonomic nervous system manages all the involuntary activity in your body — your heartbeat, your breathing, your digestion, reproductive functions, immune activity, etc.
The carbo-oxidative and lipo-oxidative systems control the way in which your cells convert nutrients into energy, and your endocrine system exerts all kinds of influences on your metabolism through the secretion of hormones, the chemical messengers that manage the activity of tissues and cells.
There are countless readily observable clues that help reveal how these systems function for you. For example, if you’re tall and have good concentration but weak digestion, these are traits that suggest something about the way your autonomic nervous system (ANS) is designed, i.e., that your body may be more influenced by the sympathetic branch of the ANS, relative to the parasympathetic branch.