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Water weight: how much does your weight change in a day?


Posted by Cags R under General on 23 July 2012 at 11:00 PM

Many of us take note of our weight; it is only natural after years of having it portrayed as being synonymous to our general health. Even when presented with facts like fat weighing less than muscle, there's still a part of us which stores too much significance on what the scales are telling us.

It was actually when I saw the Challenge to Lose 1 pound that I thought 'I'm sure I do that during a normal day?' and decided to put myself though an experiment. Obviously, like any good scientist I kept my experiment as fair as possible, eating as I normally do (ok it's slightly healthier because I knew you were watching) and keeping external variables to a minimum, so here it is, my big experiment:

How much does my weight change in the 6 hours between waking up and having lunch?

Water weight - the difference in weight over 6 hours

8:30 So let's start when I first woke up:

Apologies to those who aren't as old-school imperial as my scales
10 stone 8 pounds = 148lb

Like to think excessive sleep in my eyes is weighing me down...

First business of the morning - girl's gotta go to the bathroom:

10 stone 7 pounds = 147lb

Ok breakfast time: porridge with spoon of jam and half banana, coffee and pint of water (yes it would normally be cocopops but I went healthier for you guys!)

10 stone 10 pounds = 150lb

Pint of water whilst I work:

10 stone 11 pounds = 151lb

If this had been what I'd seen first thing this morning it would have been a massive shock, yet here it is around 2 hours later.

Toilet break:

10 stone 10 pounds = 150lb

Well done me for losing that pound - have another coffee as a treat!

Another toilet trip:

10 stone 8 pounds = 148lb

Another pint of water whilst I work.

And back to the loo before I head out for a workout:

10 stone 7 pounds = 147lb

Quick paced run followed by rowing intervals, short cycle and some burpees - no food or drink consumed during this hour long session:

10 stone 5 pounds = 145lb

Wouldn't have minded this as my wake up weight but got that smug 'Yeah I workout' feeling!

2:00 Lunch time! Today's lunch special is half a Spanish omelette with 2 slices of ham and some salad, washed down with another pint of water:

10 stone 8 pounds = 148lb

Back to my waking up weight (losing that 'Yeah I workout' feeling) and settling back to work.

So there you have it, between 8.30am and 2.30pm my weight ranged between 145-151lb! Of course the important thing to note is that my most consistant weight was 10 stone 8 pounds, the weight I woke up to (and equally important to note is that for around half an hour today I weighed 145lb - wahoo!) 

What was the point of my experiment you ask? I performed this experiment to hopefully stop anyone in the Tribesports community stepping onto the scales and have that 'Yeah I workout' feeling taken from them. Although weightloss often seems like the easiest way to measure progress it is risky; step on the scales at the wrong time of day and you could just be weighing your meal not your body. If you're putting the work in then the results will be reflected in your fitness levels, not just your waistline.

How can you accurately measure your weight? If you are tracking your weight then the best time of day to measure it is first thing in the morning, after you've had you morning bathroom trip. This way you will always have an accurate measure which will be less affected by what you have consumed that day.

How will I measure my progress from now on if I'm disregarding weight as an accurate measure?

I enjoy Challenges such as Run for an hour without walking, Set a new PB and Run a mile faster - things which measure my fitness levels improving; this year my aim is not to lose weight, I aim to gain fitness, if the other happens too that's cool but it's not what I centre my lifestyle around.

  • Encourage

    encouraged this.



    Thanks so much for confirming my suspicions! I've never tried weighing myself multiple times during a day, but have certainly found that my weight fluctuates throughout the week by up to 3-4 lbs and have driven myself crazy trying to figure out what my 'real' weight is. Thanks for proving that you shouldn't put all your faith in the scale.


    Through my own experimentation I've found that my body weight fluctuations are vaguely cyclic, but the duration of those cycles can also fluctuate by a day or two. So the idea of weighing-in at same time on the same day each week is fundamentally flawed since the body's natural rhythms do not follow a 7-day cycle.

    encouraged this.


    Why thank you @neil! Do tell more about your experiments too, what did you find? Also I recommend doing what me and my hockey mates call the Christmas day challenge - weight yourself in the morning of christmas day and again in the evening, then marvel at how much you must have in your belly!


    We actually didn't have scales in my house growing up as my mum threw them out after returning from a cycling holiday - muscley as can be - and was told by a doctor she was a little overweight. After that my family was taught the mirror test - if you don't like what you see then change it and also the world's oldest diet 'Eat less, exercise more'


    I used to find that I'd drop a pound after going in the bath! I always weigh naked before breakfast. I've got a body compositon monitor and I can upload the data to my computer. I think I'm more obsessed by numbers than I am weight.


    Wow that's really interesting (I am all about kilos too) and it also justifies to me why i bagged up the two sets of scales in our house, threw them in the garbage and happily watched the truck drive off with them...liberating!

    encouraged this.


    Wow that's really interesting (I am all about kilos too) and it also justifies to me why i bagged up the two sets of scales in our house, threw them in the garbage and happily watched the truck drive off with them...liberating!

    Bernice G encouraged this.


    Wow that's really interesting (I am all about kilos too) and it also justifies to me why i bagged up the two sets of scales in our house, threw them in the garbage and happily watched the truck drive off with them...liberating!

    Bernice G and Lynne D encouraged this.


    Thanks for the great article Cags!! Thanks for being brave enough to put it on TS. I, now, agree with the mirror/fitness test---no more scales!! I went to the doctor---had to step on the scale, was told; "you need to lose some pounds---your overweight" I said "hey doc, please practice what your preaching---I ride my bike nearly everyday with the most miles I've pedaled being 52, So when you can say you do that then I will follow a scale---but no more scales for me!! Besides I have lost 74 pounds---Your NOT taking that achievement from ME"!!! Well my doctor said OK. I might even e-mail her to tell her I registered for a duathlon :))


    Really interesting Cags, my wait fluctuates 3 or 4 lbs during the week too, I always weigh myself in the morning without fail (unless I really dont want to know) it does affect my mood even though I know really that most times it is either due to water retention or a large meal out! I walked for 3 hours last night tough terrain lots of up hill and then when I weighed myself this morning I was 2 lbs heavier than yesterday! Just weighed myself before dinner and was relieved to see I was a pound lighter! Wish I could be brave enough to chuck them away - but it is usually like a reward for all my training and healthy eating seeing those low numbers!


    @andreab1 that's what I find annoying about using weight as a marker of progress - even though you know you're improving your health by walking for 3 hours and eating healthier food, part of you feels like it's not working just because of what the scales read! If it's a case of weightloss as a goal then I find it far more satisfying to take challenges which improve your fitness and have weightloss as an added bonus - in the last 6 months I lost 7lb but what I'm most proud of is being able to run for an hour without stopping!


    Thanks for sharing this Cags - really interesting =) I tend towards a weekly weigh in and a monthly measure. As well as being nicely allitorative, they help keep me focused. But I'm finding them less and less important as my fitness levels improve =)

    encouraged this.


    I love that you did this experiment. I used to be a chronically addicted to the scale person. It was a love/hate affair. I've now been off of it for three weeks as I realized that the numbers made no sense. The scale was going up and I was obsessed with the idea that I was getting fat. Turned out that all of my army type training was translating into stronger and bigger legs and arms. So no more scale or bmi. Only go by how I feel, how I look in the mirror and how the clothes fit. And I can kick some serious ass in a Spartan race now :))))


    Hey @cags, I love this article, I feel learning ! I didn't know our weight could change that much. It makes me realize that it would have been interesting to see the change over 24-hour period to see how the night is also (or not) affecting on our weight.

    Lynne D and Joanne H encouraged this.


    Thanks @arnaud, I did collect stats later in the day too but the biggest change was in these 6 hours, it was crazy to watch! I was tempted to show how the stomach changes too (mine is always flattest in the morning) but wasn't quite that brave!

    Lynne D and Joanne H encouraged this.


    I try not to look at the scale too much. My water weight can be all over the place even after a day or two. It usually fluctuates 2-3 lbs within a day but there are some weekends where my weight can fluctuate 7lbs (up or down) or so depending on my activity and hydration levels....especially this month as I have been drinking a ton of H2O.

    Lynne D and Joanne H encouraged this.


    how true all of these comments are, but unfrotunatly for me i am still fat no matter what time of day i weigh myself. I am working on though

    Joanne H encouraged this.


    It makes me want to get a scale, to make this experiment on myself !

    Joanne H encouraged this.


    Very interesting article! Another thing I've noticed is how my weight fluctuates with the time I get up. Since I occasionally work (horrible) morning shifts from 3 and 4am, I've noticed how I at times can weigh a whole kg more on days when I work in the morning compared to the days I slept in! weaning myself off the scale, having started working out in order to lose a lot of weight that had to go, but unable to go below BMI 26 since I started getting more serious about my fitness :)

    Lucy K and Joanne H encouraged this.


    :-D cracking me up! how long was you morning pee? And how big a cup of coffee do you have...? Great experiment, did you take the bathroom scales to work?

    Joanne H encouraged this.


    Well done Cags, enjoyed your inventive and insightful article. I typically weigh myself once in the morning and call that my "dry weight" and once prior to hitting the sack at night. I have found that I fluctuate roughly 4-5 pounds over the course of the day and will almost always wake up 4-5 pounds lighter than when I went to bed - good indicator that I visit the bathroom a few times in the night :P In the end I base any weight loss or gain against my "dry weight".

    Joanne H encouraged this.


    Thanks for doing the experiment & confirming I'm not crazy & my scale does work :*) I've always been weight conscious, being that I'm only 5'0" tall. At my lowest weight--I was 97 lbs (not a good one). My heaviest was 140 (also not a good one) . Life/stress/work, over indulging & being unfit had a tremendous effect on yo-yo. In the last 2 years--I've packed on 20 lbs. Shift change at work & eating late at night--I acquired the undesired 6 pack of muffin tops. Started running again this year & in 5 months, I have dropped from 136 to now 126. I weigh myself in the mornings (after the loo :*-) & try not to get too freaked out if I gained/lost 1 or 2 lbs. After a hot, sweaty run--I've tested the scale & lost up to 1.5 lbs before (which I know is water) & I need to rehydrate. I'm ok with my slow progress to target 115/118. I'm more fit now that I have been in the last decade by eating better & exercising more. Good luck everyone on challenges. Have a great day!

    Joanne H encouraged this.


    I said this to a friend years ago and she didn't believe me. Good to see it confirmed. The scales and BMI still have their uses but being healthy and happy with how you look has got to be the best indicators there are.

    Paul T encouraged this.


    I love this article - it confirms what I have thought for a while and that's quite comforting :-) Well done and thanks for taking the time to do this.

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