How long does water weight stick around for?

I have had water weight stick around for a week. Several years ago I was in a physical therapy program and they weighed us every month. I got weighed right after the 4th of July. I had eaten out, gone to parties, for 3 days over that 4th of July weekend. I was up 7 lbs when I weighed in. A week later, I asked to be weighed again, and the 7 lbs was gone. I got weighed on a Tuesday, that weekend, I peed literally every hour for 2 days. Weighed again the next Tuesday and the weight was gone. So it stuck around for a week.

There is no way you ate 17,500 calories in a day or two over your maintenance. It's water weight and probably extra food waste, and takes time to come off.

To gain 5 pounds, you would need to eat roughly 17,500 calories above your weight maintenance calories - not just above your weight-loss calorie goal. That's really a lot: I think you'd know if you did that, even if you didn't log the whole thing. (I would recommend logging over-goal days, personally, just sayin'.)

If you didn't eat 17,500 calories above maintenance or anywhere near it, you didn't gain 5 pounds of fat, so it's mostly water weight.

How long will it last? It will vary, partly because of other conditions that can add some water retention. For me, food-triggered water retention (with no other factors) lasts anything from a couple of days to a week, rarely longer.

When I start strength training after a long break, I tend to add a couple of pounds of water weight and hang onto it as long as I continue progressive strength training on a frequent/regular schedule (but some other people have different experiences with that). When I take another long break from strength training, I usually see a couple of pounds drop on the scale with no other obvious trigger.

You appear to be female and young enough to have menstrual cycles. Most women have hormone-related water retention fluctuations that can happen any time(s) during their cycle, often on a semi-predictable schedule. A few women even say they only see a new low weight once a month at the same point in their cycle, though that isn't the most common pattern.

If you happen to have cycle-related fluctuations, it's theoretically possible that your cheat day added some water weight at a low point in your cycle-related fluctuations, then as the food-related retention dropped off over the usual couple of days, but the cycle-related water retention increased to fill the gap, so your scale weight stayed up from those triggers happening in a particular sequence.

There are dozens of things that can increase water retention either gradually or suddenly, so the above scenario could happen with any of those, too. Some examples are a respiratory allergy or a cold, exercise that holds water for muscle repair, a minor injury or illness that increases water retention for healing or inflammation reasons, and many, many more.

I'd suggest you not panic or try to take any dramatic correction measures until you've gone through at least one full menstrual cycle (if that applies) so you can compare body weight at the same relative point in two different cycles.

Even if you don't have cycles - I don't, because menopause - I'd give it like a month. I was losing slowly last time I resumed strength training so added those usual couple of pounds. There was around a month where even my weight trending app thought I was gaining or maintaining, and if I'd only been looking at the daily scale weights, it would've been confusing even longer.

Bottom line is that if you're doing the right things on average for calorie balance (food calories below all-source calorie burn), you're losing fat. The only issue is when water will stop playing peek-a-boo on the scale with the gradual fat loss.

If you haven't, this thread would be a good read, especially the article linked in the first post:

https://community.myfitnesspal.com/en/discussion/10683010/the-weird-and-highly-annoying-world-of-scale-fluctuations/p1

High odds everything's going to be fine, just from the passage of more time. Meanwhile, you have a useful opportunity to learn more about how your personal unique body responds to unusual circumstances. Hang in there!

when i do that, i literally stay off the scale for weeks and just keep counting!

You can definitely gain water weight with a salty meal like you described with the Chinese buffet. Even if you stayed within your calorie limit. And al.ost everyone gains with the hormonal ebb and flow of their cycle. Don't worry. These are very common occurrences. The water retention will go away.