I'll walk you through everything I had yesterday.

I woke up late, as always.
3 PM- Protein shake, 110 cals.
Midnight- 3 cups rice and beans, and half a chicken breast. 570 cals
The meal was very physically heavy. As in, the plate weighed a lot.
5 AM- 100 calorie pack+ a slice of bread. 200 cals.
110+570+200= 880 cals.
And here I sit, 4 pounds heavier than I should be.
Is it water weight?
I live a sedentary lifestyle, and don't usually exercise. (There's a mountain lion that lives in the woods where I used to hike, it almost killed my dog. So I don't do that anymore, and haven't since June.) So it's not that I didn't exercise. And I know I'm making excuses, but what I'm saying is that yesterday was nothing out of the norm.
Or is it from stress? I broke down and cried a lot yesterday.
I've heard that a chemical called Cortisol does this, is that true?

Well, this might not be anything after all.
I just weighed myself again, and it says I only gained one pound since yesterday, not four.

Maybe my scale's just on the fritz.

Could be water weight. Could be stress. Yes, cortisol and other hormones can cause both water weight gain, and fat gain. But in one day, you simply can't gain four pounds of fat. You're just storing water for some reason.

How many calories do you usually have in a day? 880 is pretty low. If you're eating under 1000-1300 a day on a regular basis, it can have effects on your metabolism. Not after one day, but if you're doing it all the time, it could become a problem.

For exercise, you don't need to go outside. You can get exercise videos to use at home, or go to a gym too.

I usually do 550-1000 calories a day.
(And I've ordered a treadmill online, it's just a matter of it getting here. )

I think it's just the scale, the battery's almost dead in it.
And it's pretty old.
I hadn't considered it.

3 cups of rice in one day is way too much. 1/2 cup is considered a serving, so you may want to back away from the rice a little and add some seasonal veggies, like summer squash or zucchini.

It was more like 2 cups black beans, 1 cup brown rice.
I know it was still too much, but yeah.
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It was water weight, I'm back where I should be.