Although religious in origin, I suspect that the idea of an overnight fast became a religious doctrine because of the clear health benefits. Just like many other food prohibitions in religion that have the net effect of improved public health and food safety.
Eating during the day when active raises or at least supports an active metabolism. Eating before going to sleep cause excess energy to be stored.
One can objectively cut through the diet fad, and general weightless noise by looking at the unequivocally consistent success of body builders and athletes in losing fat. This suggests that caloric deficit via increased activity is better then caloric deficit by reducing intake (generally athletes consume more calories then a typical diet, just not as many more as they burn when they are 'cutting').
The effects of the opposite behavior seem to confirm this. Sumo wrestlers build mass by eating a diet high in carbs and sleeping a lot. Mauritanian women traditionally drank camel milk and slept a lot to fatten up before marriage.
So eating the 'entire day' but stopping at least 2-4 hours before sleep seems likely to be at least moderately effective. I wonder if there's been a study... ;)