Weight gain and loss overnight

Weight fluctuates

Don't put too much stock into daily/multi-daily weight measures. Like the others said, weight fluctuates and there can be any number of factors. If it bothers you, try weighing only once a week and watch the overall trend so you aren't stressing about the normal fluctuations.

You can't gain weight overnight unless you eat or drink something during the night. I usually lose about two pounds during the night.

Some people like to weigh before and after a workout so they'll know how much fluid they need to drink in order to replace what they lost in sweat.

Fluctuations of even a few pounds day to day are essentially meaningless. Between the inherent inaccuracy of consumer-level bathroom scales and the fact that small differences in how fast you digest your previous meal and how much of yesterday's drinking water stays with you or leaves you? A few pounds mean NOTHING. You need to look at trends over time, and two or even three points do not make a trend. You need several weeks to see a trend.

I can get on the scale at night, get on it again in the morning before using the bathroom and weigh less. I envision fat cells crawling away while I sleep. (I know that is not true - don't quote me!) I don't understand HOW and I know there is no useful reason to worry about it.

Then of course I weigh less after using the bathroom than before, or weigh more after eating or drinking something. If I have an intense run I sweat. If I don't drink water, the sweat/moisture leaving my body means I weigh less. These things are examples of logical reasons of one thing or another having a direct impact on the weight that shows on the scale.

But a question: are you worried about the # the scale shows, or is your goal to actually lose fat/weight? I'm guessing its the latter and the scale is your reference point for checking your progress. If so, hang in there! Know that fluctuations are normal, caused by very normal things, and that if you eat at a deficit you will lose weight over time. Just have to give it time for the scale # to reflect your efforts.

If you want to weigh yourself, do it in a consistent manner, same time every weigh in and pick whatever makes you feel more comfortable (daily, weekly, monthly). Should be first thing in the morning, after using the bathroom and before eating. Scale on a hard surface and as little clothes as you are comfy with. I don't go back to the scale other times during the day but I know I can be up 5 lbs depending on what I've eaten.

As to how often. Consider that your weight, even under the same conditions, is going to fluctuate around 5 lbs if you are maintaining. Different amounts of water retained, food still in your system, TOM if you are female will all impact the scale reading. If you are going to be upset about your weight going up from day to day, then don't weigh daily. If you like the data, then weigh daily but use some kind of trending app or spreadsheet. You will go up and down some, but the trend should be downwards. I like to do this because it helps me see just what is going on and understand the scale reading better. It also means I can see if my week is going sideways earlier than if I weighed weekly.

If the number is really getting to you, then back off to once a month, same time, not around your TOM (assuming you have that). And focus on how your clothes fit.