5 ms·

In general, muscle is 'consumed' before 'fat'. Quotes since it is more complex than just what regular muscle and fatty tissues do. > While not healthy to liter

by consp 8y ago

In general, muscle is 'consumed' before 'fat'. Quotes since it is more complex than just what regular muscle and fatty tissues do. > While not healthy to literally starve yourself, getting your calories from stored fat is absolutely safe. No one will disagree with you there, but for most normal healthy people with regular muscle/fat content (or a bit too much) it takes a while for your body to decide it is a good idea to start creating toxins (ketones, which are quite harmless in smaller quantities) which are the result of fat conversion in a starvation diet.

joycian 8y ago
If that is true, then why even have fat instead of extra muscle? Burning muscle before fat makes no evolutionary sense.
- sergiosgc 8y ago
  > If that is true, then why even have fat instead of extra muscle? Higher density, lower basal metabolic rate increase. > Burning muscle before fat makes no evolutionary sense. The chemical pathway for getting energy from muscle is much shorter than the one to get energy from fat.
  - joycian 8y ago
    So our ancestors would just die of starvation and get weaker and weaker, while keeping their fat stores?
    - Retric 8y ago
      No, but the optimum solution to survive long term starvation is to dump as much muscle mass as possible to minimize your daily calorie burn. Alongside that the body minimizes the energy spent fighting long term problems like cancer by reducing the amount of antioxidants produced etc. Some strength is still required, so their are feedback mechanisms limiting this loss. However, on a diet you are not in pure survival mode so you probably don't want to make those same sacrifices.
      - nradov 8y ago
        That's a myth. Extra muscle doesn't contribute very much to resting metabolic rate. Fat isn't metabolically "free" either; it takes a lot of energy just to move adipose tissue around. https://muscleevo.net/muscle-metabolism/ https://muscleevo.net/muscle-metabolism/
        Retric 8y ago
        In starvation it's calories not pounds that's critical, also it's not a question of resting metabolic rate alone. Fat contains contains more than twice the energy per lb and every motion you do requires energy to move every lb of body weight. Net result storing energy in Fat takes ~1/3 the energy to maintain. So, sure it's not a huge difference per day. But, the difference between dying in 100 days or 100 + X days could make a huge difference.
        arcticbull 8y ago
        You're gonna need to cite some sources. Our side has studies to show you're wrong, and so far you've got nothing but your anecdotes.
        Retric 8y ago
        “Within FFM, skeletal muscle (-5%)” "Thirty-two nonobese men underwent sequential overfeeding (1 wk at +50% of energy needs), CR (3 wk at -50% of energy needs), and refeeding (2 wk at +50% of energy needs). AT and its determinants were measured together with body composition as assessed with the use of quantitative magnetic resonance, whole-body MRI, isotope dilution, and nitrogen and fluid balances." https://www.ncbi.nlm.nih.gov/m/pubmed/26399868/ https://www.ncbi.nlm.nih.gov/m/pubmed/26399868/ So, over 6 weeks they had zero calorie deficit but even 3 weeks of starvation result cost them 5% of their skeletal muscles lower metabolic rate, and presumably increased fat. Note: Interment fasting has nothing to do with this, it takes the body several days respond to starvation a few hours don't matter as long as net calories over 2-3 days are maintained. PS: What studies? I see a linked to an article about people over estimates of mussels energy requirements not a counter argument. You’re demonstrably wrong from both experiment and basic biochemistry.
sridca 8y ago
> In general, muscle is 'consumed' before 'fat'. Where did you glean that information? Here's my source that contradicts your statement: https://idmprogram.com/fasting-and-muscle-mass-fasting-part-14/ https://idmprogram.com/fasting-and-muscle-mass-fasting-part-...
irishcoffee 8y ago
> it takes a while for your body to decide it is a good idea to start creating toxins (ketones, which are quite harmless in smaller quantities) which are the result of fat conversion in a starvation diet. Ketones are created when your body doesn't have sugar to convert into energy. This process can take as little as 12 hours, and in no way whatsoever requires a "starvation diet"
gamblor956 8y ago
In general, muscle is 'consumed' before 'fat'. Quotes since it is more complex than just what regular muscle and fatty tissues do. Not "in general." Only specifically in cases of starvation or caloric deficit. In general, your body burns carbs, then fat, and then muscle. Muscle is by far the least efficient energy source, so the body spares muscle in normal circumstances and only consumes muscle in times of extended caloric deficit, like fasting, starvation, marathons, etc.
- naasking 8y ago
  > In general, your body burns carbs, then fat, and then muscle. Muscle is by far the least efficient energy source, so the body spares muscle in normal circumstances and only consumes muscle in times of extended caloric deficit This is a common belief but it's not true. You can't prevent your body from burning muscle in any kind of caloric deficit, you can only stimulate protein synthesis to counterbalance it by 1) ingesting high amounts of protein and 2) resistance training.
  - gamblor956 8y ago
    Some muscle is consumed in a state of caloric deficit, yes. But muscle isn't the body's first choice for fuel until you enter into a state of extended caloric deficit. If the opposite were true, then triathletes would consume a pound or more of muscle during their training activities and especially during competitive events, instead of burning visually significant quantities of fat.
    - naasking 8y ago
      > But muscle isn't the body's first choice for fuel until you enter into a state of extended caloric deficit. I'm honestly puzzled how people in this thread got the idea that I said that muscle was a preferred fuel. Literally no sequence of words I actually used imply this statement.
  - arcticbull 8y ago
    Yeah, sorry bud, you're just not in the right on this one. Your body always turns over muscle, sure, so some is going to be consumed. Your body produces huge quantities of HGH during starvation specifically to conserve protein and protein consumption goes down during fasting compared to steady-state. Otherwise our ancestors in periods of famine would turn into fatty puddles unable to drag themselves around. Starving means you need to get food, that's why noradrenaline levels go up, HGH production spikes (which many studies show changes your body composition to favor muscle over fat), your body switches to consuming primarily fat, and yes, some protein but not all protein is muscle. Your body also switches to producing what little glucose it actually needs via gluconeogenesis - which has many feedstocks including the glycerol backbones from triglycerides and yes, protein. But to say your body prefers to burn muscle over fat when starving is ridiculous, and just not supported by facts. [1] https://idmprogram.com/fasting-and-muscle-mass-fasting-part-14/ https://idmprogram.com/fasting-and-muscle-mass-fasting-part-...
arcticbull 8y ago
Ketones aren't toxins in this context, they're literally food.

by consp 8y ago

joycian 8y ago

If that is true, then why even have fat instead of extra muscle? Burning muscle before fat makes no evolutionary sense.

sergiosgc 8y ago
> If that is true, then why even have fat instead of extra muscle? Higher density, lower basal metabolic rate increase. > Burning muscle before fat makes no evolutionary sense. The chemical pathway for getting energy from muscle is much shorter than the one to get energy from fat.
- joycian 8y ago
  So our ancestors would just die of starvation and get weaker and weaker, while keeping their fat stores?
  - Retric 8y ago
    No, but the optimum solution to survive long term starvation is to dump as much muscle mass as possible to minimize your daily calorie burn. Alongside that the body minimizes the energy spent fighting long term problems like cancer by reducing the amount of antioxidants produced etc. Some strength is still required, so their are feedback mechanisms limiting this loss. However, on a diet you are not in pure survival mode so you probably don't want to make those same sacrifices.
    - nradov 8y ago
      That's a myth. Extra muscle doesn't contribute very much to resting metabolic rate. Fat isn't metabolically "free" either; it takes a lot of energy just to move adipose tissue around. https://muscleevo.net/muscle-metabolism/ https://muscleevo.net/muscle-metabolism/
      - Retric 8y ago
        In starvation it's calories not pounds that's critical, also it's not a question of resting metabolic rate alone. Fat contains contains more than twice the energy per lb and every motion you do requires energy to move every lb of body weight. Net result storing energy in Fat takes ~1/3 the energy to maintain. So, sure it's not a huge difference per day. But, the difference between dying in 100 days or 100 + X days could make a huge difference.
        arcticbull 8y ago
        You're gonna need to cite some sources. Our side has studies to show you're wrong, and so far you've got nothing but your anecdotes.
        Retric 8y ago
        “Within FFM, skeletal muscle (-5%)” "Thirty-two nonobese men underwent sequential overfeeding (1 wk at +50% of energy needs), CR (3 wk at -50% of energy needs), and refeeding (2 wk at +50% of energy needs). AT and its determinants were measured together with body composition as assessed with the use of quantitative magnetic resonance, whole-body MRI, isotope dilution, and nitrogen and fluid balances." https://www.ncbi.nlm.nih.gov/m/pubmed/26399868/ https://www.ncbi.nlm.nih.gov/m/pubmed/26399868/ So, over 6 weeks they had zero calorie deficit but even 3 weeks of starvation result cost them 5% of their skeletal muscles lower metabolic rate, and presumably increased fat. Note: Interment fasting has nothing to do with this, it takes the body several days respond to starvation a few hours don't matter as long as net calories over 2-3 days are maintained. PS: What studies? I see a linked to an article about people over estimates of mussels energy requirements not a counter argument. You’re demonstrably wrong from both experiment and basic biochemistry.

sridca 8y ago

> In general, muscle is 'consumed' before 'fat'. Where did you glean that information? Here's my source that contradicts your statement: https://idmprogram.com/fasting-and-muscle-mass-fasting-part-14/ https://idmprogram.com/fasting-and-muscle-mass-fasting-part-...

irishcoffee 8y ago

> it takes a while for your body to decide it is a good idea to start creating toxins (ketones, which are quite harmless in smaller quantities) which are the result of fat conversion in a starvation diet. Ketones are created when your body doesn't have sugar to convert into energy. This process can take as little as 12 hours, and in no way whatsoever requires a "starvation diet"

gamblor956 8y ago

In general, muscle is 'consumed' before 'fat'. Quotes since it is more complex than just what regular muscle and fatty tissues do. Not "in general." Only specifically in cases of starvation or caloric deficit. In general, your body burns carbs, then fat, and then muscle. Muscle is by far the least efficient energy source, so the body spares muscle in normal circumstances and only consumes muscle in times of extended caloric deficit, like fasting, starvation, marathons, etc.

naasking 8y ago
> In general, your body burns carbs, then fat, and then muscle. Muscle is by far the least efficient energy source, so the body spares muscle in normal circumstances and only consumes muscle in times of extended caloric deficit This is a common belief but it's not true. You can't prevent your body from burning muscle in any kind of caloric deficit, you can only stimulate protein synthesis to counterbalance it by 1) ingesting high amounts of protein and 2) resistance training.
- gamblor956 8y ago
  Some muscle is consumed in a state of caloric deficit, yes. But muscle isn't the body's first choice for fuel until you enter into a state of extended caloric deficit. If the opposite were true, then triathletes would consume a pound or more of muscle during their training activities and especially during competitive events, instead of burning visually significant quantities of fat.
  - naasking 8y ago
    > But muscle isn't the body's first choice for fuel until you enter into a state of extended caloric deficit. I'm honestly puzzled how people in this thread got the idea that I said that muscle was a preferred fuel. Literally no sequence of words I actually used imply this statement.
- arcticbull 8y ago
  Yeah, sorry bud, you're just not in the right on this one. Your body always turns over muscle, sure, so some is going to be consumed. Your body produces huge quantities of HGH during starvation specifically to conserve protein and protein consumption goes down during fasting compared to steady-state. Otherwise our ancestors in periods of famine would turn into fatty puddles unable to drag themselves around. Starving means you need to get food, that's why noradrenaline levels go up, HGH production spikes (which many studies show changes your body composition to favor muscle over fat), your body switches to consuming primarily fat, and yes, some protein but not all protein is muscle. Your body also switches to producing what little glucose it actually needs via gluconeogenesis - which has many feedstocks including the glycerol backbones from triglycerides and yes, protein. But to say your body prefers to burn muscle over fat when starving is ridiculous, and just not supported by facts. [1] https://idmprogram.com/fasting-and-muscle-mass-fasting-part-14/ https://idmprogram.com/fasting-and-muscle-mass-fasting-part-...

arcticbull 8y ago

Ketones aren't toxins in this context, they're literally food.