The FastDay Forum

Not sure if this would be better placed in the nerdy section...

But.. where does the weight go overnight?! My last few fasts have been 1iquid fasts with no evening meal, and each time I have weighed myself before going to bed (after toilet trips etc) and I wake up in the morning and weigh myself again to find I am 500-700grams lighter. I know that this weight will obviously flucuate throughout the day, and I'm currently enjoying my 2 weeks of the month where I lose weight instead of plateau... but I just don't get where it goes!!! Anyone know?

I always wonder that too! Is it the fat burning off?

Most of your food/body fat leaves your body as water through your breath and your skin, and as heat. Only a tiny part is excreted on the toilet.

you breathe in oxygen and breathe out carbon dioxide

C + O2 -> CO2

12 + 32 = 44

so part of the weight loss is expiration of carbon as carbon dioxide.

solid waste maybe 300g per day
liquid waste 2 litres ?

plus water vapour in breath and perspiration. Put a dehumidifier in your bedroom and the resulting tankful is impressive.

I like to believe it's the fat fairies coming to see me during the night

Got me thinking now....

500g of glucose is 2000 calories. That's 2.8 mols of C6H12O6 so...

C6 H12 O6 + 6 O2 --> 6 CO2 + 6 H2O
180g + 192g = 264g + 108g so a loss of 192g * 2.8 = 538g per day - just over a pound of weight to oxidised carbon.

[carorees]

Science says it's a mixture of the CO2 and H2O that is lost overnight that results in the lower weight in the morning...but I do like the idea of the fat fairies! Glassmarble, what were they called in that Dr Who episode?

V interesting, thanks all! I like the idea of breathing out fat!

Science says it's a mixture of the CO2 and H2O that is lost overnight that results in the lower weight in the morning...but I do like the idea of the fat fairies! Glassmarble, what were they called in that Dr Who episode?

Adipose

[carorees]

Adipose! Of course!

Hmmm. My fat fairy takes an average of 3 pounds overnight, every night. There must be several of them because the little ones only take 1, the big ones as much as 5.

We could quantify the result of those chemical calculations if I eliminated the nightly fluid-reduction trips, but I'd probably explode by morning.