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Where does the weight actually go?

Magrat

Mrs. Rincewind
Joined
Nov 23, 2015
Messages
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Lancre Kingdom/Adirondack Mountain Region, NY
This may be a stupid question, but I have asked it of other people and not gotten a real answer.

Where does the weight you lose actually go? Do you burn it as fuel? Excrete it? I understand that you can lose weight and fat but not the mechanism.
 
This may be a stupid question, but I have asked it of other people and not gotten a real answer.

Where does the weight you lose actually go? Do you burn it as fuel? Excrete it? I understand that you can lose weight and fat but not the mechanism.

Yes, you burn it as fuel. Though, some of it is water, which you sweat or pee out.

Basically, your body is an engine. If it gets more fuel than it uses, it stores it. If it gets less than it uses, it burns its depots.

Hans
 
Expend more energy than what you intake. If you intake 500 calories and only burn 490 calories, you gain weight. If you limit your intake to 500 but burn 510, you can loose weight. The main concern is that you have to burn fat through the correct type of exercise and you may gain weight because muscle weights more than fat.
 
I think that RogueKitten understands well that food is a fuel, and can be stored as fat, and that those reserves can be used up if there is an excess expenditure of energy compared with food intake. I think her puzzlement lies in the actual physical whereabouts of the waste products from the combustion of that fat.
 
There is a complicated chemical process in your cells by which sugars are converted into CO2, water and energy for your cells. Kind of a combustion at body temperature.
Fat and protein is converted into sugar and then used.

The assorted surplus chemicals are excreted or used as building materials for bone, muscle mass etc.
 
There is a complicated chemical process in your cells by which sugars are converted into CO2, water and energy for your cells. Kind of a combustion at body temperature.
Fat and protein is converted into sugar and then used.

The assorted surplus chemicals are excreted or used as building materials for bone, muscle mass etc.

Yes, this is what I was asking. Thank you!
 
This may be a stupid question, but I have asked it of other people and not gotten a real answer.

Where does the weight you lose actually go? Do you burn it as fuel? Excrete it? I understand that you can lose weight and fat but not the mechanism.

Excretion, yes, (including pores and lungs and the obvious), burning as fuel, yes, and that is co-with excretion. More detail???:):)
 
I think the point is the amount (of mass) converted to energy is negligible. Ergo it leaves the body after chemical conversion.
 
I did not watch the video but I suspect it covers what is important to know. There is a lot of physics and biochem involved, but you now have the layperson version and it is as full as you likely need. But continue asking if you find detail you want missing!! :)
 
I think the point is the amount (of mass) converted to energy is negligible. Ergo it leaves the body after chemical conversion.

This is why it takes longer to lose weight than it did to gain it without doing weird stuff to your body. Mostly bad idea weird stuff.
 
I actually would be interested to see the chemical equations if possible, do you have a link?

I teach high school chemistry every few years and the kids invariably ask this question. I know this is beyond the scope of my class but it is fascinating.
 
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Sugar + Oxygen = Water + Carbon Dioxide

C6H12O6 + O2 = CO2 + H2O

Balancing the equation is left as an exercise for the reader ;)
 
It becomes CO2! That's super interesting. Thank you!!

I wonder if dieters exhale more CO2 than non dieters?
Eta we are literally internal combustion engines!


No they don't. It depends on the energy you expend. Where the fuel comes from is not important.

Hans
 
Wouldn't people with higher usage of fuel breathe more though?

Yes, but a diet does not give you higher usage of fuel. It gives you a lower input of fuel.

A lot of exercise gives you a higher usage of fuel.

(I know some diets claim to increase your metabolism, but.... )

Hans
 
Yes, but a diet does not give you higher usage of fuel. It gives you a lower input of fuel.

A lot of exercise gives you a higher usage of fuel.

(I know some diets claim to increase your metabolism, but.... )

Hans

But you can't really without increasing the chemical messengers. Like pituitary stimulators or the like, which is a terrible idea to lose weight.

Metabolism isn't even a thing if you think about it, it is the sum total of certain bodily activities that we call metabolism to have something to blame when we get fat.
 
Looks like you are up for this!!!!!Except the minor O2 thing!!

Thanks sweetie! I really love chemistry. I didn't have the opportunity to study this in school (I was high) so I have learnt from books and the internet. Now I teach at our coop and everybody thinks I learned this in college lol

Eventually I will have to tell them I am an accountant ;)
 
Yes, you burn it as fuel. Though, some of it is water, which you sweat or pee out.

Basically, your body is an engine. If it gets more fuel than it uses, it stores it. If it gets less than it uses, it burns its depots.

Hans

You forgot the carbon. Carbon comes in compounds such as carbohydrates, fats and proteins. The fats and carbohydrates are entirely carbon, hydrogen and oxygen. The protein have in addition to these three elements some nitrogen, sulfur and phosphorus.

The compounds are oxidized as you loose wight. Oxidation here means the addition of oxygen There are other forms of oxidation, but this is the most important types. The molecules are broken down as they oxidize.

Most of oxidized compounds are released as the gases carbon dioxide and water vapor. Some of the nitrogen (from proteins) is released in urea crystals suspended the urine.

I don't know where the sulfur and phosphorus go when protein is oxidized. My suspicion is that these two elements are also released in the urine.

Along with oxidized compounds, some liquid water leaves the body in the urine and in the breath. If water vapor was not excreted in this way, then the body would be bloated after the person has loosed carbohydrate, fats and protein.

The majority of weight lost is released as carbon dioxide and water. A smaller amount of weight is lost as urea in urine. I don't exactly know how the rest of it is lost.
 
You might find the Krebs cycle interesting.

"If you think you understand cellular respiration, you've missed something." I don't know who said it, but I read it while trying to learn why I pee dark urine with exercise.

And no, fats do not have to be converted to sugar to burn. Though the fats have to have their chains broken to single 'links' to get to the mitochondria. Which is my problem- my mitos lack the stuff it takes to get those molecules in. So the fat gets stored in the cells. And my cells run out of energy and die. The dark urine is from excess red oxygen carrying protein from the destroyed cells. It's called myoblobin, the pee is myoglobinuria.

Though back to the OP: When I lost 60 pounds in 3 months, the scale showed the loss overnight. Water and CO2 were both exhaled. All part of cellular respiration- Sugars are converted to ATP while NOT doing exercise. And the oxygen to burn the ATP is also taken in and stored as another compound, all ready to go for the first exertion. So that is called 'anerobic exercise', no deep breathing needed. But fats need oxygen as burnt, so it's called 'aerobic'.

Unless, of course, I missed something. :D
 
Oh, the mildew on bedroom walls is caused by the dampness from the water you exhale alll niiigghht looong.

Go ahead, weigh yourself tonight, and again before urinating in the moring, see how much weight you've exhaled. Or go ahead and peee into a measure, "a pint's a pound the world around". I'll leave the math up to the students.
 
I understand it as far as what happens in your body, I was interested in the actual chemical reaction. If you have a resource on that I'd love it! When I search I find illustrations of the kreb cycle but not the equation behind it.

It's more often called the 'citric acid cycle' these days and is very complicated indeed. We did it in a BioSci BSc course and it was hard going. Not to be studied lightly ;)

One aspect of weight gain/loss that intrigues me is the case of skinny people who can eat a lot without gaining weight (I'm one, it seems). We hear that they have very busy metabolisms but there's still the question of how that energy is expressed. I'm a total fidget, but it takes an awful lot of fidgeting to burn significant calories. Running a higher basal body temperature? Mine's normal. Maybe it's higher heat losses based on surface area/volume ratio?
 
You forgot the carbon. Carbon comes in compounds such as carbohydrates, fats and proteins. The fats and carbohydrates are entirely carbon, hydrogen and oxygen. The protein have in addition to these three elements some nitrogen, sulfur and phosphorus. *snip*

I didn't forget it. I just took it all together as "fuel", for simplicity. At that point it was not clear that the OP wanted a detailed description, but I see that is being supplied now.

Hans
 
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There is a complicated chemical process in your cells by which sugars are converted into CO2, water and energy for your cells. Kind of a combustion at body temperature.
Fat and protein is converted into sugar and then used.

The assorted surplus chemicals are excreted or used as building materials for bone, muscle mass etc.

Yes and the cool thing to remember is that our enzymes are catalysts. They permit the reactions of combustion to be initiated at lower temperature than chemical burning. The energy is also released and passed on to various reactive compounds in small aliquots rather than the uncontrolled whoosh of chemical combustion.
 
The inverse question is interesting to ask too. Where do plants get their weight from? Most do not know it's water and CO2. And yes it's complex but eventually that is what we turn our food back into. But it is possible to pause the process and make stores in the form of fat.
 
<snip>

One aspect of weight gain/loss that intrigues me is the case of skinny people who can eat a lot without gaining weight (I'm one, it seems). We hear that they have very busy metabolisms but there's still the question of how that energy is expressed. I'm a total fidget, but it takes an awful lot of fidgeting to burn significant calories. Running a higher basal body temperature? Mine's normal. Maybe it's higher heat losses based on surface area/volume ratio?

I think the answer is what skinny people eat. Their sugar intake is very low. They eat a lot of fruit and veg.
 
You forgot the carbon. Carbon comes in compounds such as carbohydrates, fats and proteins. The fats and carbohydrates are entirely carbon, hydrogen and oxygen. The protein have in addition to these three elements some nitrogen, sulfur and phosphorus.

The compounds are oxidized as you loose wight. Oxidation here means the addition of oxygen There are other forms of oxidation, but this is the most important types. The molecules are broken down as they oxidize.

Most of oxidized compounds are released as the gases carbon dioxide and water vapor. Some of the nitrogen (from proteins) is released in urea crystals suspended the urine.

I don't know where the sulfur and phosphorus go when protein is oxidized. My suspicion is that these two elements are also released in the urine.

Along with oxidized compounds, some liquid water leaves the body in the urine and in the breath. If water vapor was not excreted in this way, then the body would be bloated after the person has loosed carbohydrate, fats and protein.

The majority of weight lost is released as carbon dioxide and water. A smaller amount of weight is lost as urea in urine. I don't exactly know how the rest of it is lost.
[nitpicky]
Historically, and in this case, yes.

But the current, more widely working definition of "oxidation" is "loss of electrons of the chemical species". Giving the electrons to oxygen is a very common occurrence of that (that's why it's called that and had the original definition), but far from being the only one.
[/nitpicky]
 

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