My Austrian grandfather had the same habit, and while I never inquired, I suspect it had a similar sort of origin - of his brothers, all those I had the chance to know shared it.

Whether this had any effect on their all having been successful small business owners, one of whom manufactured parts used in every Space Shuttle orbiter, I can't really speculate - that's just one of the many conversations I'll never quite be done regretting the preclusion of opportunity to have with these very worthy and remarkable men, none of whom survived into this millennium. But it wouldn't surprise me all that much.

I think there's a Japanese saying about stopping you're 4/5ths full, and there are other sayings like "tie off the sack before it's full," etc. I have been trying it recently and I definitely feel less lethargic in general, especially after lunch, but after dinner too.