Another odd thing is that this only started a couple years ago. I wonder if it's connected somehow to eating on an irregular schedule. I lived in a homeless shelter for eight years, where meals were served three times a day, always at the same times. I held down full-time employment for most of the time I lived there (I was trying to get out of debt, which was made easier by not having to choose between paying on the debt and paying rent/buying groceries), so meal times were irregular when I was working, but since I worked as a cook it was a simple matter to nibble on something as soon as I felt the first hints of hunger.
I don't cook for a living now, though, so eating at work is mostly limited to break times, which can sometimes be far enough apart that my stomach starts to complain.