[Donald Edward]

Donald Edward  asked the Naked Scientists:
   
I've noticed that if I weigh myself before and after my morning shower
(or bath), I always weigh LESS after the shower (or bath), whether it's
a short or long shower, hot or tepid.  As far as I'm concerned, I should 
weigh more after a shower, since my body should have retained some
moisture. I originally weighed myself before and after to see if the
moisture would be apparent in my weight, but once I noticed that I would
consistently get two different measurements, it became impossible to
weigh myself only once, I always weight myself before and after, and the
after reading is ALWAYS less.

I Googled for this and found a lot of other people with exactly the
same question, and I've read a lot of silly explanations.  I don't urinate
in the shower, I don't wash off 1 pound of dirty and I'm not a hot air
balloon, so I don't believe I weigh less because I am hotter.

I have an "electronic" scale with a glass surface located 2 rooms
away from the shower.

I have the same mass after the shower, the only difference being
that I contain a little more outer moisture and, my body outer 
skin should conduct more electricity, but I can't see how that
would affect the scale's reading of my weight.

Aside from the fact that you probably think I'm a little crazy, would
you have an explanation for this phenomenon ?

Thank you for your time.

Donald Edward.
What do you think?

[yor_on]

Think you need to give some examples of the weight difference firstly. And writing that you have the same mass after the shower doesn't make sense if you on the other tentacle say that you weight less. Mass is a term of invariance whereas weight will differ, depending on where you weight yourself. So unless you step into the bath on, let's say the moon, and then 'teleport' to earth after stepping out of it? That would join a same mass with different weights, before and after :) Ah, or vice versa..

[Jolly]

Donald Edward  asked the Naked Scientists:
   
I've noticed that if I weigh myself before and after my morning shower
(or bath), I always weigh LESS after the shower (or bath), whether it's
a short or long shower, hot or tepid.  As far as I'm concerned, I should
weigh more after a shower, since my body should have retained some
moisture. I originally weighed myself before and after to see if the
moisture would be apparent in my weight, but once I noticed that I would
consistently get two different measurements, it became impossible to
weigh myself only once, I always weight myself before and after, and the
after reading is ALWAYS less.

I Googled for this and found a lot of other people with exactly the
same question, and I've read a lot of silly explanations.  I don't urinate
in the shower, I don't wash off 1 pound of dirty and I'm not a hot air
balloon, so I don't believe I weigh less because I am hotter.

I have an "electronic" scale with a glass surface located 2 rooms
away from the shower.

I have the same mass after the shower, the only difference being
that I contain a little more outer moisture and, my body outer
skin should conduct more electricity, but I can't see how that
would affect the scale's reading of my weight.

Aside from the fact that you probably think I'm a little crazy, would
you have an explanation for this phenomenon ?

Thank you for your time.

Donald Edward.
What do you think?

Well you do loose dead skin, hair and dirt during a shower, so there would just with that, be some loss, a minimal one.

Still heat probably does change weight because atoms vibrate more when they are hot compared to when they are cold. 

I once did an experiment with two chocolate bars dropping them at the same time- the one heated fell faster.

[zx16]

Probably the water from the shower has washed some dirt away

[syhprum]

May I suggest that you take care to empty your bladder before weighing your self previous to showering, spraying your self with hot water in my experience stimulates urination which it would  be hard to resist either in the shower or after leaving the shower before the second weighing.

[syhprum]

Jolly, I repeated your experiment with a hot plate and a cool one and the hot one certainly hit the ground first

PS burnt fingers !!

[jeffreyH]

Jolly, I repeated your experiment with a hot plate and a cool one and the hot one certainly hit the ground first

I have been talking about this idea with various friends for about 10 years saying there may be a temperature difference in rates of freefall. However it needs to be conducted in a vacuum to discount buoyancy effects. If it still shows a difference then it is fundamental to the gravitational attraction and not trivial.

[Bored chemist]

My bathroom scales read differently if I lean forward or back a bit.
I can imagine being nice + relaxed after a shower would promote a different stance and a different apparent weight.

[Jolly]

Jolly, I repeated your experiment with a hot plate and a cool one and the hot one certainly hit the ground first

Interesting isnt it- Probably because mass and energy- by adding heat you are adding energy, so the object therefore has more weight or more energy. Things are slightly heavier when you touch them

[syhprum]

It would be a superfine bathroom scale indeed if it could detect the increase in mass due to acquired energy after a shower.