Research published in autumn of 2009 concludes that eating high calorie food after 8pm results in 48% more of the calories being turned into fat. This research was instigated following the observation that night shift workers have much higher incidents of obesity and other weight related problems.
The body has its own body clock and is aware of the time of day. It also knows that night time is ‘sleep’ time so there is no need to keep those calories ‘near the surface’ available for instant use because you are unlikely to need to run away from a sabre tooth tiger or produce a sudden burst of energy whist you sleep. Consequently, it will convert these excess calories into fat storage. And this is the reason for problems with night shift workers because they are forced to eat at times that are not natural (evolution wise).
This adds credence to that old adage “Breakfast like a king, lunch like a prince and dine like a pauper.” So, it is not just about calories in and calories out.