I don’t put too much stock in online nutrition and fitness advice, but here is what at least one article (Fashion Beans) suggests in the day or two after overindulgence.

• Day 1: Start by drinking a whole bunch of water to start flushing salt from the system. Delay caffeine intake for an hour or two (ha, no chance I would ever do this, I have my priorities.) Basically just eat protein, vegetables, and a little bit of vegetable-based fat the rest of the day (hopefully there are some of these amongst the leftovers.) Take a 10-minute walk after every meal (probably never a bad idea). Exercise, but only lightly (as defined by the fitness bro who probably wrote this post.) Give alcohol a break. Get a solid sleep (they say 7.5 hours, sounds a bit overprecise to me).
• Day 2: Lots of yogurt and fruit and more protein for breakfast.

And that’s it. Sounds totally fine for general health advice. We know what we are supposed to do right? Sleep, exercise, vegetables, fruits, nuts, seeds, whole grains, protein, approved fats and oils in moderation. 0-1 alcoholic beverages per day and avoid sugar and processed foods almost entirely. Do this for a couple days and you will probably feel decent whether you behaved badly on day 0 or not, I would think. Behave badly for several days in a row, as at least I tend to do over holiday breaks and on vacation, and you might start to feel pretty crappy. So here’s the best piece of advice I can give: Do as I say, not as I do!