I've been trying to exercise more (now that my foot is healed and it's easy to sit at home for way too long) ... now I'm sad to hear that I'm causing global warming.
When we lose weight, where does it go?
41–50 of 131 posts
Re: When we lose weight, where does it go?
#42This reminded me of the book: "Big Fat Myths: When You Lose Weight, where Does the Fat Go?" by Ruben Meerman.
Then I noticed he was one of the authors.
Re: When we lose weight, where does it go?
#43> The most common misconception by far, was that fat is converted to energy. The problem with this theory is that it violates the law of conservation of matter, which all chemical reactions obey. I mean what they're getting at must be true, we are obviously not converting 1kg of rest mass into energy but that sentence is very much not true.
Agreed. It's the most pedantic claim I've seen on the internet all of 2020. By that logic sugar and gasoline don't get converted to energy either. Edit: actually, this is the worst article I've read on the internet in all of 2020.
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Re: When we lose weight, where does it go?
#44> The most common misconception by far, was that fat is converted to energy. The problem with this theory is that it violates the law of conservation of matter, which all chemical reactions obey. I mean what they're getting at must be true, we are obviously not converting 1kg of rest mass into energy but that sentence is very much not true.
Agreed. It's the most pedantic claim I've seen on the internet all of 2020. By that logic sugar and gasoline don't get converted to energy either. Edit: actually, this is the worst article I've read on the internet in all of 2020.
Where does a ball go when you drop it off a cliff? It turns in to energy, of course! No, it goes to the bottom of the cliff. The process releases energy, but the ball did not turn into energy.
Re: When we lose weight, where does it go?
#45Earlier quoted context omitted.
In what way is it not true? When a reaction does convert mass to energy we call it a nuclear reaction
Chemical reactions also lose mass according to E=mc^2, but m is so small that it's hard to notice.
Yup. For example (which I calculated because I was curious), the direct mass conversion equivalent for 2000 food calories of energy is about 93 nanograms. Compare that to the typical value that 1lb of fat is about 3500 calories of usable energy.
Re: When we lose weight, where does it go?
#46Earlier quoted context omitted.
Was this in the US? I went to a very large public middle school and high school in Texas, so our experiences may differ, but it was certainly standard there. (This, of course, varies even district to district, but perhaps my experience isn't as general as I imagined.)
I can't image that the mechanism isn't taught. I mean, this is basic biology that we probably all learned in middle school, and certainly had to learn in chemistry class. But I think we just fail to put 2-and-2 together, even the teachers. I think I was in my late 20s when it dawned on me that I was exhaling the food I ate. But I came to that realization in a matter of seconds based on first principles--principles le…
> I think I was in my late 20s when it dawned on me that I was exhaling the food I ate. But I came to that realization in a matter of seconds based on first principles--principles learned in middle and high school.
But as noted elsewhere in the thread, you mostly aren't exhaling your food. Respiration is a reaction that takes in O2 and produces CO2. The only thing you can get rid of by breathing is carbon. But you need to excrete a mixture of carbon, hydrogen, oxygen, and nitrogen. (Plus trace elements.)
Re: When we lose weight, where does it go?
#47Water and CO2? (And, of course, some other byproducts, but by and large.) I mean, I think this is a well-known answer, no? Sorry I don't mean to sound facetious, I haven't opened the article, so I may be surprised, but I thought this was standard knowledge (at least, it was taught in middle school and high school, even though that's been a while ago for me).
I recall from Chemistry: When hydrocarbons combust, the outputs generally are CO2 and Water. Driven home by living with a gearhead after college. At least some of the liquid dripping from tailpipes is water.
Also relevant if you've ever looked into what a modern "condensing" boiler/furnace is:
https://www.ernstheating.com/blog/condensing-furnaces/
A consequence of the secondary heat exchanger is that a bunch of the steam from the exhaust condenses back into water, and unfortunately it's water containing a bunch of heavy metals and other nasty stuff, which usually ends up flushed into the municipal sanitary sewer. Probably still better than it going up the chimney and into the atmosphere, but it would be nice if there was a way to capture and isolate those pollutants in that relatively concentrated state, before they end up mixed in with everyone's bathtub water.
Re: When we lose weight, where does it go?
#48The story is (likely purposefully) ignoring some other ways you can "lose weight/energy" from your body. But I am curious what would the complete list be...
* heat (the most obvious one, not explicitly mentioned I guess?)
* even in healthy humans, some fatty acids are excreted with bile into the gut and subsequently removed via feces
* if you are fasting (or in ketosis, such as via keto diet) you will exhale / sweat ketone bodies, which is a very ineffective way (energy balance wise) to use up fatty acids
* if you are a diabetic, you can excrete glucose in your urine; we have subsequently develop drugs that can help mimic this process as a diabetes treatment
* skin, hair and nails (very insignificant amounts)
* sperm & menses
Anybody got anything else I am not currently thinking about?
Re: When we lose weight, where does it go?
#49Water and CO2? (And, of course, some other byproducts, but by and large.) I mean, I think this is a well-known answer, no? Sorry I don't mean to sound facetious, I haven't opened the article, so I may be surprised, but I thought this was standard knowledge (at least, it was taught in middle school and high school, even though that's been a while ago for me).
Yes, something like (CH2O)n + n O2 → n H2O + n CO2 for sugars and analogous for fats and proteins.
Re: When we lose weight, where does it go?
#50When we lose fat, we breath it away CO2.