So, living in the heart of the Midwest as I do, it only makes sense that I'm going to find myself in a, um, discussion here and there about my vegan lifestyle. Some people are genuinely curious, and some (of course) are just out for blood. (Pun intended.)
Anyway, one question that a friend-of-a-friend asked was whether vegetarians digested food faster than omnivores. I should have asked her for the reasoning behind the question, I guess... I assume it has something to do with the myth that vegetarians are perpetually hungry. Good question, anyway.
The thing is, how fast food is digested really doesn't have much to do with it - the vast majority of the digestion process takes place in the intestines, not the stomach. So whether vegetarians digest food faster or slower than omnivores doesn't have much of an effect on how often they feel hungry.
Now, as far as the omnivore vs. vegetarian digestion speed comparison issue, all the research materials I can find suggest that plant foods are quite a bit tougher to break down than animal flesh, so it takes your body longer to digest plant based foods. It appears that's why humans have intestinal tracts that are quite a bit longer than strictly carniverous animals, but shorter than those of strictly vegetarian animals.
So, for all practical purposes, it seems that the digestion process is actually slower for vegetarians than for omnivores. This is assuming, of course, that we're talking about a vegetarian that primarily eats plant foods, rather than one who primarily eats Twinkies and potato chips. Processed foods are, of course, excellent straight-to-fat vehicles that don't require a whole lot of consideration from your digestive tract.
To the extent that digestion speed actually matters, the slow process of plant food digestion faciliatates even, long term energy, while the faster process of animal flesh digestion provides faster (but shorter-lasting) energy. I suppose that makes sense from a practical perspective, too (or at least it did, once upon a time) - hunters of old needed quicker energy to keep from becoming dinner themselves, while gatherers needed long-term energy to search for edible vegetation.
Although, to me, it's largely an academic question, I still enjoyed researching it... and maybe the slower digestion of plant-based foods does partially account for why I started feeling better, and having more consistent energy, when I went vegan. I plan on doing additional research, though, to see if this digestion issue has other implications.
The "vegetarians are always hungry" thing is still a sham, though. I mean take around my blog, and the others on my blogroll. There are enough amazing recipes to try something new every day for years! Many of us have a backlog of things we're waiting for the chance to try out.... how many carnivores do you know that can say that? :-)