

Why you lose a pound of weight at night in your sleep - ternaryoperator
http://www.npr.org/blogs/krulwich/2013/06/19/193556929/every-night-you-lose-more-than-a-pound-while-youre-asleep-for-the-oddest-reason

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usea
Just because you're inhaling molecules that have 2 oxygen atoms, and exhaling
molecules that have 2 oxygen atoms for every 1 carbon atom, doesn't mean
you're exhaling more matter than you're inhaling. The numbers are ratios. They
don't imply a larger volume. Not to mention the composition of what you inhale
and exhale is not simply oxygen and carbon dioxide.

As it usually goes, reality is much more nuanced than this short article
implies.

I know nothing about this topic. I definitely don't know enough to say this
reason for losing weight is wrong. However, the explanation is utterly
unconvincing.

edit: apparently there's a youtube video that didn't load for me the first
time. I think it's trying to say that for the same volume CO₂, there's more
mass? I think I should have avoided commenting on a subject that I know little
about.

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gus_massa
See the video! It's has interesting information in spite of the informal
format.

Back of the envelope calculations at 5:15 (I checked them and look legit)

Experimental measures at 2:06 and 4:07.

~~~
gus_massa
But it's also possible to gain some mass from the Oxygen in the air. The
burning reactions for example typical compounds are:

 __Typical sugar (Glucose) C6H12O6

C6H12O6 + 6 x O2 (air) ---> 6 x CO2 (air) + 6 x H2O

6 Carbons get exhaled, and you lost a little of mass.

 __Typical Fatty Acid (Palmitic) CH3(CH2)14COOH

CH3-(CH2)14-COOH + 23 x O2 (air) ---> 16 x CO2 (air) + 16 x H2O

16 Carbons get exhaled, but 14 Oxygens get absorbed in water. The mass of the
Oxigens (14x16) is slightly more than the mass of the Carbons (16x12), so you
gain a little of mass. But this is much smaller.

 __Typical aminoacid: more complicated.

I think that the total mass lost dew to the first kind of reaction is much
bigger than the total mass gained dew to the second. So the calculations in
the video are probably a good approximation.

(Anyway, most of the difference is water (transpiration / exhaling).)

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pdog
Is this actually true, or is it water vapor (H2O) that we're expelling each
night?

