Hrm.

Once a calorie is burned....there is nothing left. So when food is digested and absorbed as energy, there is nothing left to redigest and get reabsorbed.

As for the "partially digested" well the part that did get digested first is used for energy. The part still hanging around to be digested will be used when it's time is up. This is one of those black and white issues. It is either digested, or yet to be digested, but no way can you count it's calories twice.

Not sure who came up with that, but any biology 101 course would cover that I think.

As for time of day....many people have different opinions on this...

some say don't eat 3 hours prior to bed, reasoning behind this is your body slows down to rest and the food in your stomach digests more slowly....

some say it doesn't matter, the FIFO reasoning. Calories burned to calories eaten should be equal if it's more you gain, if it's less you lose.

Not sure who is right. My personal opinion is if I eat right before bed, I have really weird/bad dreams, so I stick with the 3 to 4 hour rule because I really don't like weird dreams

Chao.