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The purpose of Ketones

stevencloserstevencloser Posts: 8,917Member Member Posts: 8,917Member Member
I'm reading up on metabolism things right now but I don't seem to understand what exactly Ketones are good for.

If I'm reading this right, normally, fatty acids get turned to Acetyl-CoA, which then gets turned to energy in the Krebs cycle.

During ketosis, the liver has to use the stuff that is necessary to do this for gluconeogenesis though, so it instead creates Ketones out of the Acetyl-CoA. But it looks like the only way Ketones can be used to get energy is to get turned back to Acetyl-CoA, so what exactly are the Ketones good for then if they need to get turned back into what it was before?
(Bonus non-biological question: And why do so many people strive for Ketosis if it's just an intermediate product that just gets turned back to the normal one later on?)
edited March 2016
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Replies

  • queenliz99queenliz99 Posts: 15,358Member Member Posts: 15,358Member Member
    Good question. In to learn.
  • punkrockgothpunkrockgoth Posts: 534Member, Premium Member Posts: 534Member, Premium Member
    Fair warning. My knowledge of the subject is pretty much limited to the couple of lectures I had in my university Nutrition course. Someone else can likely answer the question better.

    Think of your body like a campfire. Glucose is like newspaper. It burns quickly and easily. Glycogen, which is stored glucose is like those little sticks and stuff. A little bit more work to burn, but not really difficult.

    When you stop eating carbs, your body no longer has glucose to turn into acetyl-CoA, so it turns to fat. Which is like those big *kitten* logs. It's going to take some work to burn.

    Now if your body has glucose available, it will act like newspaper and help to burn those big logs that are fat. When your body runs out of newspaper, or glucose, all it can do is turn to fat. Now if you've ever lit a fire before, you'll know that you can't just throw a match on a big log and expect to roast some marshmallows on there. You need to chop it up.

    So your body does some stuff to break down the fat and turn it into something that can be used to make acetyl-CoA, ketones.

    People strive for ketosis because it's a sign that your body is using stored fat as it's primary fuel source. Staying in this state for too long can cause a buildup of ketones in the blood stream and cause ketone acidosis. That is bad. That is dangerous.

    I'm really not sure if I answered your question or just repeated stuff you already know.
  • nvmomketonvmomketo Posts: 12,031Member Member Posts: 12,031Member Member
    Sort of like the ATP - ADP energy cycle? Why bother right?
  • lithezebralithezebra Posts: 3,684Member Member Posts: 3,684Member Member
    Great question! I don't know, but I'd like to figure it out. This blog post from Scientific American is relevant. It suggests that you get more energy per unit of oxygen out of fatty acids than out of carbs, which could decrease oxidative stress. Apparently long term ketosis also increases the number of mitochondria in the brain.

    http://blogs.scientificamerican.com/mind-guest-blog/the-fat-fueled-brain-unnatural-or-advantageous/
  • lithezebralithezebra Posts: 3,684Member Member Posts: 3,684Member Member
    Oh, of course the big thing that ketones do for you is to provide fuel for the brain, which can't use fatty acids directly, and also for heart and muscle cells, thus sparing the small amount of glucose derived from the glycerol in triglycerides for cells, liver cells for example, that can't use ketones. The brain may have a small absolute glucose requirement too.
    edited March 2016
  • GaleHawkinsGaleHawkins Posts: 7,623Member Member Posts: 7,623Member Member
    @lithezebra thanks for the link. I have been in a state of ketosis for the past 18 months as a side effect of my successful by diet pain management and would like more research on living on ketones long term.
  • Sabine_StroehmSabine_Stroehm Posts: 19,389Member Member Posts: 19,389Member Member
    shell1005 wrote: »
    Fair warning. My knowledge of the subject is pretty much limited to the couple of lectures I had in my university Nutrition course. Someone else can likely answer the question better.

    Think of your body like a campfire. Glucose is like newspaper. It burns quickly and easily. Glycogen, which is stored glucose is like those little sticks and stuff. A little bit more work to burn, but not really difficult.

    When you stop eating carbs, your body no longer has glucose to turn into acetyl-CoA, so it turns to fat. Which is like those big *kitten* logs. It's going to take some work to burn.

    Now if your body has glucose available, it will act like newspaper and help to burn those big logs that are fat. When your body runs out of newspaper, or glucose, all it can do is turn to fat. Now if you've ever lit a fire before, you'll know that you can't just throw a match on a big log and expect to roast some marshmallows on there. You need to chop it up.

    So your body does some stuff to break down the fat and turn it into something that can be used to make acetyl-CoA, ketones.

    People strive for ketosis because it's a sign that your body is using stored fat as it's primary fuel source. Staying in this state for too long can cause a buildup of ketones in the blood stream and cause ketone acidosis. That is bad. That is dangerous.

    I'm really not sure if I answered your question or just repeated stuff you already know.

    Nope, not true.

    If you stay in ketosis for an extended period of time...you won't cause a buildup and then cause ketoacidosis. Ketoacidosis is when the body stops regulating ketone production and only tends to happen in untreated diabetics and long time alcoholics. I wish people would stop fear mongering and sharing that myth that a keto diet and ketoacidosis have anything to do with one another.

    I believe shel is correct on this on. Ketoacidosis is a whole other thing, unrelated to ketosis. I bet the original banting investigators and their predecessors wish they'd figured out another word, and popularized that. If memory serves, Dr. Atkins tried to "rebrand" the process.

    ETA: yes, apparently Atkins and his contemporaries tried to refocus the discussion to "lipolysis".
    edited March 2016
  • nvmomketonvmomketo Posts: 12,031Member Member Posts: 12,031Member Member
    lithezebra wrote: »
    Great question! I don't know, but I'd like to figure it out. This blog post from Scientific American is relevant. It suggests that you get more energy per unit of oxygen out of fatty acids than out of carbs, which could decrease oxidative stress. Apparently long term ketosis also increases the number of mitochondria in the brain.

    http://blogs.scientificamerican.com/mind-guest-blog/the-fat-fueled-brain-unnatural-or-advantageous/

    I've always loved Scientific American. Thanks for the link.
  • Sabine_StroehmSabine_Stroehm Posts: 19,389Member Member Posts: 19,389Member Member
    nvmomketo wrote: »
    lithezebra wrote: »
    Great question! I don't know, but I'd like to figure it out. This blog post from Scientific American is relevant. It suggests that you get more energy per unit of oxygen out of fatty acids than out of carbs, which could decrease oxidative stress. Apparently long term ketosis also increases the number of mitochondria in the brain.

    http://blogs.scientificamerican.com/mind-guest-blog/the-fat-fueled-brain-unnatural-or-advantageous/

    I've always loved Scientific American. Thanks for the link.

    I enjoy it as well. And enjoyed this link.
  • dpwellmandpwellman Posts: 3,271Member Member Posts: 3,271Member Member

    During ketosis, the liver has to use the stuff that is necessary to do this for gluconeogenesis though, so it instead creates Ketones out of the Acetyl-CoA. But it looks like the only way Ketones can be used to get energy is to get turned back to Acetyl-CoA, so what exactly are the Ketones good for then if they need to get turned back into what it was before?
    That is correct. They're good for when glucose is unavailable. As long as one's liver is healthy and otherwise under-taxed, keytones can be used as energy in a "pinch"

    The following applies to otherwise healthy individuals

    So why do people (in the pursuit of weight loss) try to force ketosis? Because it has very rapid initial "gains" towards the goal of weight loss, but it still remains a sub-optimal strategy. Firstly, all things being equal, the fat-loss delta between low-carb and low fat diets disappears in 12 to 18 months. That delta is relevant because following long term low-carb, there remains a "no going back" threshold where the re-introduction of carbohydrates to a normal level will very likely lead to rapid fat gain. Secondly, just because your brain and muscles can use keytones doesn't mean that they "want" to. Glucose is always the "preferred" energy source. Mental acuity and muscular endurance suffer when glucose is not available. I'm thinking specifically of a twin study done in UK (I think) that tested that hypothesis and their results support it. Lastly, low-carb diets consequently tend to be high in fat-- of particular concern, saturated fat. Again, as stated previously, carb restriction has very rapid initial results, however long term adherence mortgages future cardiovascular health in pursuit of those results.

    It remains that in either strategy, neither the low carb lost weight (excess fat) solely because he was low carb. Nor did the low fat lose weight solely because low-fat, but because of a calorie deficit.

    Best bet for long term: fruits, vegetables, some whole grains here and there, and avoid high concentrations of simple sugars and saturated fats.
    edited March 2016
  • eric_sg61eric_sg61 Posts: 2,931Member Member Posts: 2,931Member Member
    dpwellman wrote: »

    During ketosis, the liver has to use the stuff that is necessary to do this for gluconeogenesis though, so it instead creates Ketones out of the Acetyl-CoA. But it looks like the only way Ketones can be used to get energy is to get turned back to Acetyl-CoA, so what exactly are the Ketones good for then if they need to get turned back into what it was before?
    That is correct. They're good for when glucose is unavailable. As long as one's liver is healthy and otherwise under-taxed, keytones can be used as energy in a "pinch"

    The following applies to otherwise healthy individuals

    So why do people (in the pursuit of weight loss) try to force ketosis? Because it has very rapid initial "gains" towards the goal of weight loss, but it still remains a sub-optimal strategy. Firstly, all things being equal, the fat-loss delta between low-carb and low fat diets disappears in 12 to 18 months. That delta is relevant because following long term low-carb, there remains a "no going back" threshold where the re-introduction of carbohydrates to a normal level will very likely lead to rapid fat gain. Secondly, just because your brain and muscles can use keytones doesn't mean that they "want" to. Glucose is always the "preferred" energy source. Mental acuity and muscular endurance suffer when glucose is not available. I'm thinking specifically of a twin study done in UK (I think) that tested that hypothesis and their results support it. Lastly, low-carb diets consequently tend to be high in fat-- of particular concern, saturated fat. Again, as stated previously, carb restriction has very rapid initial results, however long term adherence mortgages future cardiovascular health in pursuit of those results.

    It remains that in either strategy, neither the low carb lost weight (excess fat) solely because he was low carb. Nor did the low fat lose weight solely because low-fat, but because of a calorie deficit.

    Best bet for long term: fruits, vegetables, some whole grains here and there, and avoid high concentrations of simple sugars and saturated fats.

    This is where people who folllow low carb gurus are going to pay a heavy price.
  • GaleHawkinsGaleHawkins Posts: 7,623Member Member Posts: 7,623Member Member
    eric_sg61 wrote: »
    dpwellman wrote: »

    During ketosis, the liver has to use the stuff that is necessary to do this for gluconeogenesis though, so it instead creates Ketones out of the Acetyl-CoA. But it looks like the only way Ketones can be used to get energy is to get turned back to Acetyl-CoA, so what exactly are the Ketones good for then if they need to get turned back into what it was before?
    That is correct. They're good for when glucose is unavailable. As long as one's liver is healthy and otherwise under-taxed, keytones can be used as energy in a "pinch"

    The following applies to otherwise healthy individuals

    So why do people (in the pursuit of weight loss) try to force ketosis? Because it has very rapid initial "gains" towards the goal of weight loss, but it still remains a sub-optimal strategy. Firstly, all things being equal, the fat-loss delta between low-carb and low fat diets disappears in 12 to 18 months. That delta is relevant because following long term low-carb, there remains a "no going back" threshold where the re-introduction of carbohydrates to a normal level will very likely lead to rapid fat gain. Secondly, just because your brain and muscles can use keytones doesn't mean that they "want" to. Glucose is always the "preferred" energy source. Mental acuity and muscular endurance suffer when glucose is not available. I'm thinking specifically of a twin study done in UK (I think) that tested that hypothesis and their results support it. Lastly, low-carb diets consequently tend to be high in fat-- of particular concern, saturated fat. Again, as stated previously, carb restriction has very rapid initial results, however long term adherence mortgages future cardiovascular health in pursuit of those results.

    It remains that in either strategy, neither the low carb lost weight (excess fat) solely because he was low carb. Nor did the low fat lose weight solely because low-fat, but because of a calorie deficit.

    Best bet for long term: fruits, vegetables, some whole grains here and there, and avoid high concentrations of simple sugars and saturated fats.

    This is where people who folllow low carb gurus are going to pay a heavy price.

    Well at least we know the inputs come from people who had not experienced the keto eating life style. :)

    While I did not go LCHF to lose weight the weight loss was an accident that took place. After keto cured my cravings the weight came off without having to count calories in my case.

  • eric_sg61eric_sg61 Posts: 2,931Member Member Posts: 2,931Member Member
    eric_sg61 wrote: »
    dpwellman wrote: »

    During ketosis, the liver has to use the stuff that is necessary to do this for gluconeogenesis though, so it instead creates Ketones out of the Acetyl-CoA. But it looks like the only way Ketones can be used to get energy is to get turned back to Acetyl-CoA, so what exactly are the Ketones good for then if they need to get turned back into what it was before?
    That is correct. They're good for when glucose is unavailable. As long as one's liver is healthy and otherwise under-taxed, keytones can be used as energy in a "pinch"

    The following applies to otherwise healthy individuals

    So why do people (in the pursuit of weight loss) try to force ketosis? Because it has very rapid initial "gains" towards the goal of weight loss, but it still remains a sub-optimal strategy. Firstly, all things being equal, the fat-loss delta between low-carb and low fat diets disappears in 12 to 18 months. That delta is relevant because following long term low-carb, there remains a "no going back" threshold where the re-introduction of carbohydrates to a normal level will very likely lead to rapid fat gain. Secondly, just because your brain and muscles can use keytones doesn't mean that they "want" to. Glucose is always the "preferred" energy source. Mental acuity and muscular endurance suffer when glucose is not available. I'm thinking specifically of a twin study done in UK (I think) that tested that hypothesis and their results support it. Lastly, low-carb diets consequently tend to be high in fat-- of particular concern, saturated fat. Again, as stated previously, carb restriction has very rapid initial results, however long term adherence mortgages future cardiovascular health in pursuit of those results.

    It remains that in either strategy, neither the low carb lost weight (excess fat) solely because he was low carb. Nor did the low fat lose weight solely because low-fat, but because of a calorie deficit.

    Best bet for long term: fruits, vegetables, some whole grains here and there, and avoid high concentrations of simple sugars and saturated fats.

    This is where people who folllow low carb gurus are going to pay a heavy price.

    Well at least we know the inputs come from people who had not experienced the keto eating life style. :)

    While I did not go LCHF to lose weight the weight loss was an accident that took place. After keto cured my cravings the weight came off without having to count calories in my case.

    Plenty of people have tried low carb/keto and paid the piper
    https://www.facebook.com/180degreehealth/posts/1193989860629357
  • JeromeBarry1JeromeBarry1 Posts: 10,118Member Member Posts: 10,118Member Member
    I wonder if the difference between a <100 carb diet and a <50 carb diet is anything.
  • lithezebralithezebra Posts: 3,684Member Member Posts: 3,684Member Member
    I wonder if the difference between a <100 carb diet and a <50 carb diet is anything.

    Yes. You can be pretty sure that you're in ketosis at <50 grams of carbs/day. People trying to control seizures are likely to eat <20.
  • lithezebralithezebra Posts: 3,684Member Member Posts: 3,684Member Member
    eric_sg61 wrote: »
    eric_sg61 wrote: »
    dpwellman wrote: »

    During ketosis, the liver has to use the stuff that is necessary to do this for gluconeogenesis though, so it instead creates Ketones out of the Acetyl-CoA. But it looks like the only way Ketones can be used to get energy is to get turned back to Acetyl-CoA, so what exactly are the Ketones good for then if they need to get turned back into what it was before?
    That is correct. They're good for when glucose is unavailable. As long as one's liver is healthy and otherwise under-taxed, keytones can be used as energy in a "pinch"

    The following applies to otherwise healthy individuals

    So why do people (in the pursuit of weight loss) try to force ketosis? Because it has very rapid initial "gains" towards the goal of weight loss, but it still remains a sub-optimal strategy. Firstly, all things being equal, the fat-loss delta between low-carb and low fat diets disappears in 12 to 18 months. That delta is relevant because following long term low-carb, there remains a "no going back" threshold where the re-introduction of carbohydrates to a normal level will very likely lead to rapid fat gain. Secondly, just because your brain and muscles can use keytones doesn't mean that they "want" to. Glucose is always the "preferred" energy source. Mental acuity and muscular endurance suffer when glucose is not available. I'm thinking specifically of a twin study done in UK (I think) that tested that hypothesis and their results support it. Lastly, low-carb diets consequently tend to be high in fat-- of particular concern, saturated fat. Again, as stated previously, carb restriction has very rapid initial results, however long term adherence mortgages future cardiovascular health in pursuit of those results.

    It remains that in either strategy, neither the low carb lost weight (excess fat) solely because he was low carb. Nor did the low fat lose weight solely because low-fat, but because of a calorie deficit.

    Best bet for long term: fruits, vegetables, some whole grains here and there, and avoid high concentrations of simple sugars and saturated fats.

    This is where people who folllow low carb gurus are going to pay a heavy price.

    Well at least we know the inputs come from people who had not experienced the keto eating life style. :)

    While I did not go LCHF to lose weight the weight loss was an accident that took place. After keto cured my cravings the weight came off without having to count calories in my case.

    Plenty of people have tried low carb/keto and paid the piper
    https://www.facebook.com/180degreehealth/posts/1193989860629357

    That's an opinion piece, offering no citations, not only an opinion piece, but one intended to sell books. Do you have peer-reviewed studies that support the assertion that months or years of not eating carbs will cause "insomnia, low energy levels, depression, dry skin, constipation, sexual apathy, and so on?"

    Dude is selling books on how to raise your metabolic rate: http://www.amazon.com/Matt-Stone/e/B001KIM1IA/?_encoding=UTF8&camp=1789&creative=390957&linkCode=ur2&tag=180degr-20

    edited March 2016
  • Christine_72Christine_72 Posts: 16,074Member Member Posts: 16,074Member Member
    I wonder if the difference between a <100 carb diet and a <50 carb diet is anything.

    I was thinking the same... Particularly the part of what 'could' happen if one goes back to eating carbs, referenced by @dpwellman
    edited March 2016
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