If you look at a calendar from 100-200 years ago - say, 1800 - you will see how many saints' days there were. People were expected to fast on certain days, feast on others. I suppose this was a system that had been worked out (not necessarily "planned" by an elder or a committee, though who knows what kind of control went on, way back when?) to help with food distrubution amongst the populace. It was normal to go without all food for a day or two, or without certain foods - usually scarcities like land animals and their products - for a longer period, e.g., Lent. Later, there was a feast of some kind. The entire year was broken up into this on/off pattern, not just at major holidays like Easter.
When people now laugh about overeating at Christmas, they are simply honoring tradition, if you really think about it. The trouble is, they do not honor tradition all the time! They never fast. They never go without certain foods as a way of 1) respecting scarcity; 2) valuing the foods they consume by going without them from time to time (absence makes the heart grow fonder). That lopsided "traditional" behavior contributes, no doubt, to the epidemic of obesity in Western countries, the plague of food waste, the proliferation of intense farming operations, and the attendant environmental pollution and animal cruelty. More appreciative consumers would better honor the living beings who feed them.
Maybe it's time to bring back some of the old ways - while we still have the freedom to choose to abstain. Any future scarcities - leading to local or widespread famine - will force us to go without luxuries and maybe without minimal daily nutrients. How about starting a fashion for pre-holiday fasts? They wouldn't involve starvation, just selective abstinence and calorie reduction. How much better roasted bird and high-calorie desserts would taste after a week of bean soup and dry crackers!