Our corner of the world also has a similar saying: "Keep the breakfast for yourself, give half the lunch to your enemy, and let them have the dinner."

However I have a sneaking suspicion this grew out of generations of peasants who needed almost 5 digit daily calories early in the day to sustain their backbreaking farm labor, and helped along by moralizing against lazy people who would get the village in trouble with the local lord or the imperial tax collectors.