Preferably before. I walk about 5 to 10 km when i get home. And I walk fast so I burn about 400 to 800 calories and I sweat like a pig (oops......dog). I'm really knackered afterwards but after about an hour you feel really mellow and relaxed.

Walking after eating probably has some risks. You will force blood to the surface of your skin and this might have a side effect on the digestive process - similar to taking a bath after a meal. Any doctors in the house? Correct me if I'm wrong.

That's just my personal experience. Hope it helps.