This is a really good question that doesn't seem answerable by the best experts.  There are many who claim to have the answer, but for every plausible explanation, there is a great counter answer.

Personally, I think there is something to be said for how much food is in your stomach in need of digesting while your body's metabolism has slowed down to sleep.  But I have to believe that whatever you don't digest while sleeping would still "be there" for your body to metabolize when you awaken.  

The truth probably lies somewhere in the middle.  While it's not going to be good for you to go to bed every night with a ton of food in the stomach, it's probably not going to be a problem if you like to have a 10 pm small bowl of cereal every night before retiring.  (Also, going to bed with an extremely full stomach puts major stress on one's heart and circulatory system.)

What I am very sure of, however, is that the whole matter is probably not of much consequence.  If the answer to this question held promise that it would have a major impact on people's weight issues, believe me, it would be answered and understood.  

Truth is, the most important thing is to manage one's calories overall, eat reasonably-timed, well-portioned meals to incorporate your necessary number of calories, and you will lose weight.  

If people would eliminate or minimize sugars and unhealthy fats, eat more fruits & vegetables and exercise more, the question of nighttime eating would become a very small issue. 

I know ... boring ... but true!