T Nation

Overnight Weight Fluctuations


I have noticed that I drop 6-8 lbs from the time I go to bed and the time I wake up. I weigh myself with the same scale and same amount of clothes. I was just wondering if this happens to other people. I pee 2 times in between the night time and the morning but I just do not think it is 6-8lbs of water. I was wondering if anyone knew the mechanism behind this.



happens to everyone. The food in your stomach and the water throughout your body is used overnight as you sleep, resulting in a lower morning body weight then evening body weight.


You sweat a lot while sleeping.


Diabetes? Kidney problems?

Anyway, you don’t just pee out water, you also sweat and breathe. But 6-8 pounds is quite a bit. So tell us how much you drink in a day, how much you eat in a day, if you by any chance consume alcohol or any other diuretics. Is it like this every night or just some nights? How long has it been like this?

You can PM me (or answer here) and I’ll try to find the problem or go to a doctor and (if he doesn’t suggest it) ask him to test your urine and your blood.

It’s not pleasant, but measuring how much you pee per night would be of diagnostic value. If you do it, weigh yourself before and after that night as well.


I’m around 230 right now, and I drink 7-10 liters of water a day.

I usually lose 3-7 pounds after going to sleep and waking up and peeing twice during the night. 1 gallon of water weighs 8 pounds…


Well I consume anywhere from 6-10 liters a day. Food wise I have no idea how mnay lbs I eat but its a lot (3300-3500 of “clean” food). No diuretics or alcohol. No diabetes or kidney problems. Just had a fairly extensive checkup and liver kidney and lots of other things were checked and all came back good. Its been 4nights now. I wasnt really thinking I was sick or anything I guess. I just thought it was pretty crazy.


Then that sounds completely normal :slight_smile:


I figured it was kinda normal just wondering the nechanism. Thanks for the replies.


You’ll probably notice quite a difference between weighing yourself before and after showering just from your skin absorbing water, many many factors play into your weight just try and be consistent about when you weigh yourself.


I shower a 3 or 4 hours before bed and never before I weigh myself. I always keep as many variables constant as possible. Thanks for the advice.


In addition to what everyone has said so far, people don’t often realize how much water they lose just by breathing. Exhaled air is nearly 100% humidity, so in a dry room it would be pretty normal to lose up to a quart of water over night.