You&#x27;re partly right.  The primary byproduct of bacterial fermentation is short-chain fatty acids.  These do in fact stimulate the release of peptide YY, which reduces gastric motility.  It is extremely unlikely that the bacteria are the ones &quot;hacking&quot; us though; short chain fatty acid production is the result of fairly ubiquitous, low level pathways whereas modulation of hormone release is a fairly specialized, high level function.