Why you lose a pound of weight at night in your sleep
npr.org
npr.org
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.
Back of the envelope calculations at 5:15 (I checked them and look legit)
Experimental measures at 2:06 and 4:07.
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).)