In youth, a person may be disturbed by external forces. I don’t care what the force is, other than it is something that produces anxiety as the disturbance.
Anxiety triggers the release of lots of different chemicals in the body. One possible side-effect of some of those chemicals is a sensation in the stomach. I’ll call it queasiness, just to offer a label.
Every time an external force produces anxiety, that same queasiness arises, to some degree. Eventually there arises a link, a learned link or strong association in the youthful brain between the queasiness and anxiety.
The youth becomes an adult, carrying along the association. But a problem arises. Queasiness may arise for many reasons other than anxiety. What, then, if the association between queasiness and anxiety is strong enough that the brain’s amazing circuits search FIRST for anxious thoughts BEFORE evaluating the queasiness?
In this sequence, it is the queasiness that gives rise to the associated anxiety. So perhaps a handful of blueberries taken with a tumbler of orange juice after a glazed old-fashioned donut gave rise to the queasiness, eh? And the brain has, without notifying the person, found something to be anxious about. Food can wreck the mood, all right.
Of course, food is not the only thing that can give rise to queasiness. But you get the picture. Easy-peasy-queasy-uneasy. Oh, and we are not forced to indulge the associations we have between body states and mental states. We can weaken or eliminate some of the less-useful links through awareness.