When we lose weight, where does it go?

I was curious, so I looked it up, watched a fascinating Ted Talk about the mathematics of weight loss and learned this:

84% of fat is exhaled as CO2 (carbon dioxide)

16% of fat is excreted as H20 (water)

Not sure if it's accurate, but it was really interesting, and definitely over my head!
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Replies

  • tomcustombuilder
    tomcustombuilder Posts: 1,530 Member
    That's pretty much what happens.
  • BarbaraHelen2013
    BarbaraHelen2013 Posts: 1,940 Member
    As far as I understand it, most of the ‘energy’ is exhaled as Carbon Dioxide when you breathe.

    I notice that there’s a definite link with urination in the early days but that’s water balance due to potentially a lower carbohydrate load in your diet. Carbohydrates require water to metabolise.

    So, basically what your podcast taught you is accurate.
  • Arimicsan
    Arimicsan Posts: 1 Member
    That’s really interesting! I’m going to have to check that Ted talk out. Thanks for sharing!
  • neanderthin
    neanderthin Posts: 9,808 Member
    Yep, but the percentages vary depending on the source but it's always in and around the 80 % 20% range.
  • lynn_glenmont
    lynn_glenmont Posts: 9,950 Member
    As far as I understand it, most of the ‘energy’ is exhaled as Carbon Dioxide when you breathe.

    I notice that there’s a definite link with urination in the early days but that’s water balance due to potentially a lower carbohydrate load in your diet. Carbohydrates require water to metabolise.

    So, basically what your podcast taught you is accurate.

    That's not quite right. The energy is used, not "exhaled." It comes from breaking down complex molecules, and CO2 is the major waste product of that process.
  • sollyn23l2
    sollyn23l2 Posts: 1,528 Member
    As far as I understand it, most of the ‘energy’ is exhaled as Carbon Dioxide when you breathe.

    I notice that there’s a definite link with urination in the early days but that’s water balance due to potentially a lower carbohydrate load in your diet. Carbohydrates require water to metabolise.

    So, basically what your podcast taught you is accurate.

    That's not quite right. The energy is used, not "exhaled." It comes from breaking down complex molecules, and CO2 is the major waste product of that process.

    In a way. Yes, you have to "use" the energy by various and sundry activities in order to release it from your cells, but it is ultimately breathed out and expelled. You have to remember, energy cannot be created nor destroyed, merely changed. If we didn't expel it as we breathe, it would stay in our body.
  • neanderthin
    neanderthin Posts: 9,808 Member
    edited May 2023
    sollyn23l2 wrote: »
    As far as I understand it, most of the ‘energy’ is exhaled as Carbon Dioxide when you breathe.

    I notice that there’s a definite link with urination in the early days but that’s water balance due to potentially a lower carbohydrate load in your diet. Carbohydrates require water to metabolise.

    So, basically what your podcast taught you is accurate.

    That's not quite right. The energy is used, not "exhaled." It comes from breaking down complex molecules, and CO2 is the major waste product of that process.

    In a way. Yes, you have to "use" the energy by various and sundry activities in order to release it from your cells, but it is ultimately breathed out and expelled. You have to remember, energy cannot be created nor destroyed, merely changed. If we didn't expel it as we breathe, it would stay in our body.

    Yes, we are talking about the metabolic breakdown of adipose (body fat) here and not how all energy sources are used per se. Body fat (triglycerides) are basically fatty acids chains with a glycerol backbone that contain chains of carbon, oxygen and hydrogen, which are converted to adenosine triphosphate (ATP) then oxidized to CO2 and H20 by beta oxidation and the citric acid cycle, so it's expelled (converted) through breath to C02 and through water loss through sweat and urine for example. The glycerol part of that fatty acid chain after beta oxidation is what can be used for gluconeogenesis, which is the making of new glucose. short story. Cheers
  • Retroguy2000
    Retroguy2000 Posts: 1,430 Member
    sollyn23l2 wrote: »
    As far as I understand it, most of the ‘energy’ is exhaled as Carbon Dioxide when you breathe.

    I notice that there’s a definite link with urination in the early days but that’s water balance due to potentially a lower carbohydrate load in your diet. Carbohydrates require water to metabolise.

    So, basically what your podcast taught you is accurate.

    That's not quite right. The energy is used, not "exhaled." It comes from breaking down complex molecules, and CO2 is the major waste product of that process.
    In a way. Yes, you have to "use" the energy by various and sundry activities in order to release it from your cells, but it is ultimately breathed out and expelled. You have to remember, energy cannot be created nor destroyed, merely changed. If we didn't expel it as we breathe, it would stay in our body.
    You're forgetting heat.
  • sollyn23l2
    sollyn23l2 Posts: 1,528 Member
    edited May 2023
    sollyn23l2 wrote: »
    As far as I understand it, most of the ‘energy’ is exhaled as Carbon Dioxide when you breathe.

    I notice that there’s a definite link with urination in the early days but that’s water balance due to potentially a lower carbohydrate load in your diet. Carbohydrates require water to metabolise.

    So, basically what your podcast taught you is accurate.

    That's not quite right. The energy is used, not "exhaled." It comes from breaking down complex molecules, and CO2 is the major waste product of that process.
    In a way. Yes, you have to "use" the energy by various and sundry activities in order to release it from your cells, but it is ultimately breathed out and expelled. You have to remember, energy cannot be created nor destroyed, merely changed. If we didn't expel it as we breathe, it would stay in our body.
    You're forgetting heat.

    Yes, heat is another way our body releases energy back out into the world.
    ETA: This is why your breath is hot, not cold.
  • sollyn23l2
    sollyn23l2 Posts: 1,528 Member
    edited May 2023
    sollyn23l2 wrote: »
    As far as I understand it, most of the ‘energy’ is exhaled as Carbon Dioxide when you breathe.

    I notice that there’s a definite link with urination in the early days but that’s water balance due to potentially a lower carbohydrate load in your diet. Carbohydrates require water to metabolise.

    So, basically what your podcast taught you is accurate.

    That's not quite right. The energy is used, not "exhaled." It comes from breaking down complex molecules, and CO2 is the major waste product of that process.

    In a way. Yes, you have to "use" the energy by various and sundry activities in order to release it from your cells, but it is ultimately breathed out and expelled. You have to remember, energy cannot be created nor destroyed, merely changed. If we didn't expel it as we breathe, it would stay in our body.

    Yes, we are talking about the metabolic breakdown of adipose (body fat) here and not how all energy sources are used per se. Body fat (triglycerides) are basically fatty acids chains with a glycerol backbone that contain chains of carbon, oxygen and hydrogen, which are converted to adenosine triphosphate (ATP) then oxidized to CO2 and H20 by beta oxidation and the citric acid cycle, so it's expelled (converted) through breath to C02 and through water loss through sweat and urine for example. The glycerol part of that fatty acid chain after beta oxidation is what can be used for gluconeogenesis, which is the making of new glucose. short story. Cheers

    Energy is energy. The triglycerides in fat cells are simply stored energy being held in stasis until our body releases it.
  • neanderthin
    neanderthin Posts: 9,808 Member
    edited May 2023
    sollyn23l2 wrote: »
    sollyn23l2 wrote: »
    As far as I understand it, most of the ‘energy’ is exhaled as Carbon Dioxide when you breathe.

    I notice that there’s a definite link with urination in the early days but that’s water balance due to potentially a lower carbohydrate load in your diet. Carbohydrates require water to metabolise.

    So, basically what your podcast taught you is accurate.

    That's not quite right. The energy is used, not "exhaled." It comes from breaking down complex molecules, and CO2 is the major waste product of that process.

    In a way. Yes, you have to "use" the energy by various and sundry activities in order to release it from your cells, but it is ultimately breathed out and expelled. You have to remember, energy cannot be created nor destroyed, merely changed. If we didn't expel it as we breathe, it would stay in our body.

    Yes, we are talking about the metabolic breakdown of adipose (body fat) here and not how all energy sources are used per se. Body fat (triglycerides) are basically fatty acids chains with a glycerol backbone that contain chains of carbon, oxygen and hydrogen, which are converted to adenosine triphosphate (ATP) then oxidized to CO2 and H20 by beta oxidation and the citric acid cycle, so it's expelled (converted) through breath to C02 and through water loss through sweat and urine for example. The glycerol part of that fatty acid chain after beta oxidation is what can be used for gluconeogenesis, which is the making of new glucose. short story. Cheers

    Energy is energy. The triglycerides in fat cells are simply stored energy being held in stasis until our body releases it.

    Triglycerides are fat cells in this context, anyway that wasn't my point. Cheers
  • sollyn23l2
    sollyn23l2 Posts: 1,528 Member
    sollyn23l2 wrote: »
    sollyn23l2 wrote: »
    As far as I understand it, most of the ‘energy’ is exhaled as Carbon Dioxide when you breathe.

    I notice that there’s a definite link with urination in the early days but that’s water balance due to potentially a lower carbohydrate load in your diet. Carbohydrates require water to metabolise.

    So, basically what your podcast taught you is accurate.

    That's not quite right. The energy is used, not "exhaled." It comes from breaking down complex molecules, and CO2 is the major waste product of that process.

    In a way. Yes, you have to "use" the energy by various and sundry activities in order to release it from your cells, but it is ultimately breathed out and expelled. You have to remember, energy cannot be created nor destroyed, merely changed. If we didn't expel it as we breathe, it would stay in our body.

    Yes, we are talking about the metabolic breakdown of adipose (body fat) here and not how all energy sources are used per se. Body fat (triglycerides) are basically fatty acids chains with a glycerol backbone that contain chains of carbon, oxygen and hydrogen, which are converted to adenosine triphosphate (ATP) then oxidized to CO2 and H20 by beta oxidation and the citric acid cycle, so it's expelled (converted) through breath to C02 and through water loss through sweat and urine for example. The glycerol part of that fatty acid chain after beta oxidation is what can be used for gluconeogenesis, which is the making of new glucose. short story. Cheers

    Energy is energy. The triglycerides in fat cells are simply stored energy being held in stasis until our body releases it.

    Triglycerides are fat cells in this context, anyway that wasn't my point. Cheers

    I'm not disagreeing with you. You're mostly right. It's simply that your description overcomplicates the reality of what's happening... which is a form of energy transfer.
  • neanderthin
    neanderthin Posts: 9,808 Member
    sollyn23l2 wrote: »
    sollyn23l2 wrote: »
    sollyn23l2 wrote: »
    As far as I understand it, most of the ‘energy’ is exhaled as Carbon Dioxide when you breathe.

    I notice that there’s a definite link with urination in the early days but that’s water balance due to potentially a lower carbohydrate load in your diet. Carbohydrates require water to metabolise.

    So, basically what your podcast taught you is accurate.

    That's not quite right. The energy is used, not "exhaled." It comes from breaking down complex molecules, and CO2 is the major waste product of that process.

    In a way. Yes, you have to "use" the energy by various and sundry activities in order to release it from your cells, but it is ultimately breathed out and expelled. You have to remember, energy cannot be created nor destroyed, merely changed. If we didn't expel it as we breathe, it would stay in our body.

    Yes, we are talking about the metabolic breakdown of adipose (body fat) here and not how all energy sources are used per se. Body fat (triglycerides) are basically fatty acids chains with a glycerol backbone that contain chains of carbon, oxygen and hydrogen, which are converted to adenosine triphosphate (ATP) then oxidized to CO2 and H20 by beta oxidation and the citric acid cycle, so it's expelled (converted) through breath to C02 and through water loss through sweat and urine for example. The glycerol part of that fatty acid chain after beta oxidation is what can be used for gluconeogenesis, which is the making of new glucose. short story. Cheers

    Energy is energy. The triglycerides in fat cells are simply stored energy being held in stasis until our body releases it.

    Triglycerides are fat cells in this context, anyway that wasn't my point. Cheers

    I'm not disagreeing with you. You're mostly right. It's simply that your description overcomplicates the reality of what's happening... which is a form of energy transfer.

    A triglyceride as a description for the release of adipose is as simplistic as it gets. That is what this topic is about after all. Tell you what, I won't get into the metabolism of heat, so I don't further complicate it, lol. cheers
  • AnnPT77
    AnnPT77 Posts: 31,721 Member
    As far as I understand it, most of the ‘energy’ is exhaled as Carbon Dioxide when you breathe.

    I notice that there’s a definite link with urination in the early days but that’s water balance due to potentially a lower carbohydrate load in your diet. Carbohydrates require water to metabolise.

    So, basically what your podcast taught you is accurate.

    That's not quite right. The energy is used, not "exhaled." It comes from breaking down complex molecules, and CO2 is the major waste product of that process.

    I agree with this. The "energy" is consumed via heat, movement, and in miscellaneous cellular and biochemical processes that require an input of energy to work. The waste products of breaking down food into energy are water and exhaled gases, primarily CO2. Most of the energy isn't exiting one's body with the waste products. Primarily the energy went elsewhere. (Yes, conservation of energy applies, it isn't created or destroyed, but it can be converted between forms, such as from stored forms - food or body fat - into, for example, into kinetic energy involved in movement.)

    Loosely, it's like a car: The gas is burned to create the energy that moves the car down the road, and does some other intra-car utility work. Energy doesn't somehow stay in the car (or body), and energy doesn't primarily leave in the exhaust fumes. Energy (using words loosely) turns into "work".

    The human body isn't dramatically different, except that we do have those options for turning food into stored energy. (I guess you could look at the alternator/battery as doing a sort of analogous thing in the car, but batteries can't get obese AFAIK.)
  • sollyn23l2
    sollyn23l2 Posts: 1,528 Member
    AnnPT77 wrote: »
    As far as I understand it, most of the ‘energy’ is exhaled as Carbon Dioxide when you breathe.

    I notice that there’s a definite link with urination in the early days but that’s water balance due to potentially a lower carbohydrate load in your diet. Carbohydrates require water to metabolise.

    So, basically what your podcast taught you is accurate.

    That's not quite right. The energy is used, not "exhaled." It comes from breaking down complex molecules, and CO2 is the major waste product of that process.

    I agree with this. The "energy" is consumed via heat, movement, and in miscellaneous cellular and biochemical processes that require an input of energy to work. The waste products of breaking down food into energy are water and exhaled gases, primarily CO2. Most of the energy isn't exiting one's body with the waste products. Primarily the energy went elsewhere. (Yes, conservation of energy applies, it isn't created or destroyed, but it can be converted between forms, such as from stored forms - food or body fat - into, for example, into kinetic energy involved in movement.)

    Loosely, it's like a car: The gas is burned to create the energy that moves the car down the road, and does some other intra-car utility work. Energy doesn't somehow stay in the car (or body), and energy doesn't primarily leave in the exhaust fumes. Energy (using words loosely) turns into "work".

    The human body isn't dramatically different, except that we do have those options for turning food into stored energy. (I guess you could look at the alternator/battery as doing a sort of analogous thing in the car, but batteries can't get obese AFAIK.)

    Yes. This is true. I also think a lot of people have the misunderstanding that after the work is done the energy has been used up and is gone, when really, it's basically been transferred and released, in a simplistic way of speaking. The way it's released is through Neanderthin's explanation. None of this really matters for our purposes, it's just interesting
  • ClearNotCloudyMind
    ClearNotCloudyMind Posts: 238 Member
    Searched this clip up on YouTube and watched the whole thing. Am reminded of why I didn’t entirely hate chemistry at school. My brain and waistline both thank you for sharing!

    My takeaway. We gain mass in a form which stores excess energy for future use. When we don’t take in sufficient fuel our bodies metabolise those stores, releasing both the saved energy and the mass that stored it. Hence weight loss.

    Delightful!
  • Skyler103
    Skyler103 Posts: 121 Member
    It sure seems like the percentages should be reversed when I have to pee 20 times a day right before a whoosh!
  • AnnPT77
    AnnPT77 Posts: 31,721 Member
    Skyler103 wrote: »
    It sure seems like the percentages should be reversed when I have to pee 20 times a day right before a whoosh!

    It's because (in a lot of cases) a whoosh is a quick release of water retention, not a quick release of fat.

    Theory is that the fat loss was creeping along in the background, masked by water retention slowly creeping on (possibly because of diet-related physical stress and cortisol, possibly other reasons). The water can release rather suddenly, unmask the fat loss that had been happening, but that was hidden by the water retention.
  • neanderthin
    neanderthin Posts: 9,808 Member
    edited May 2023
    AnnPT77 wrote: »
    Skyler103 wrote: »
    It sure seems like the percentages should be reversed when I have to pee 20 times a day right before a whoosh!

    It's because (in a lot of cases) a whoosh is a quick release of water retention, not a quick release of fat.

    Theory is that the fat loss was creeping along in the background, masked by water retention slowly creeping on (possibly because of diet-related physical stress and cortisol, possibly other reasons). The water can release rather suddenly, unmask the fat loss that had been happening, but that was hidden by the water retention.

    I've read that and it sounds like the logical conclusion even though it's apparently a hypothesis at the moment. That would be a very expensive ward study waiting for that to happen and then determining that was the actual cause and the conclusions from a study needs a control for comparison purposes, yeah for sure, way too expensive and never going to happen....It's a good hypothesis and one I'm willing to bet on. Cheers
  • robertw486
    robertw486 Posts: 2,379 Member
    https://community.myfitnesspal.com/en/discussion/10650701/biochemistry-answers-to-weight-loss-questions-where-does-the-weight-go

    For those not into the in-depth chemistry just don't let your eyes glaze over, but it will still all make sense.