I doubt very much that a deer's stomach goes thru any significant changes during this time. This may have been brought about by those who noticed that deer tend to change over somewhat as acorns and other woods browse become available and crops were being harvested. However, the notion that they eat less at this time is incorrect since this is when they're attempting to gain weight before winter and the beginning of the rut.

Today's small bucks are tomorrow's trophies.