Why do we lose muscle in a calorie deficit?
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CM_73
Posts: 554 Member
And what sort of ratio to fat is it? Or does that vary wildly according to genetics/working out/protein intake etc.
Why does the body lose muscle at all, is it just easier to metabolise than fat, or is it stripped off as it's too "expensive" for the body to maintain when it's in calorific deficit?
I'm purely asking out of interest, I'm at a small deficit, keeping my protein up and lifting regularly, just curious as to what I'll lose and why! (if it's even answerable)
Why does the body lose muscle at all, is it just easier to metabolise than fat, or is it stripped off as it's too "expensive" for the body to maintain when it's in calorific deficit?
I'm purely asking out of interest, I'm at a small deficit, keeping my protein up and lifting regularly, just curious as to what I'll lose and why! (if it's even answerable)
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Replies
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Wildly varies, but that's why the standard advice here is to eat high protein and lift heavy, which is what you are doing.3
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My, somewhat non-scientific, understanding is this.
Ratio of fat/LBM loss in caloric deficit will depend upon:- Existing Fat/LBM composition - where more body fat will mean more body fat loss versus LBM.
- Adequate protein intake (see http://ajcn.nutrition.org/content/103/3/738.full)
- Presence or lack of muscle stimulus - Strength type exercise being touted as muscle sparing.
- The severity of the deficit - Steeper deficit will tilt the ratio of LBM/Fat loss towards the LBM
- Genetics - I assume (but I'm prepared to be wrong) that some people are genetically predisposed to retain more muscle in a loss situation than others.
Why would the body use muscle in the first place and not just burn off the fat? I think you've got it right in your original post, muscle is energetically expensive and in times of low food input the body will attempt to reduce energy consumption by making you move less (lethargy and reduction of NEAT) and by reduction in the energy overhead associated with muscle.
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StealthHealth wrote: »My, somewhat non-scientific, understanding is this.
Ratio of fat/LBM loss in caloric deficit will depend upon:- Existing Fat/LBM composition - where more body fat will mean more body fat loss versus LBM.
- Adequate protein intake (see http://ajcn.nutrition.org/content/103/3/738.full)
- Presence or lack of muscle stimulus - Strength type exercise being touted as muscle sparing.
- The severity of the deficit - Steeper deficit will tilt the ratio of LBM/Fat loss towards the LBM
- Genetics - I assume (but I'm prepared to be wrong) that some people are genetically predisposed to retain more muscle in a loss situation than others.
Why would the body use muscle in the first place and not just burn off the fat? I think you've got it right in your original post, muscle is energetically expensive and in times of low food input the body will attempt to reduce energy consumption by making you move less (lethargy and reduction of NEAT) and by reduction in the energy overhead associated with muscle.
In my unscientific opinion, this is correct. Although I would argue that severity of the deficit only comes in to play when an individual is lean already. A large deficit when you have a high bodyfat percentage isn't really an issue.2 -
@trigden1991 That's a good point.. I agree that obese could be aggressive with deficit and have rapid fat loss with low to zero muscle loss.1
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Thanks all, it makes sense to me, just something I'd wondered about.trigden1991 wrote: »StealthHealth wrote: »My, somewhat non-scientific, understanding is this.
Ratio of fat/LBM loss in caloric deficit will depend upon:- Existing Fat/LBM composition - where more body fat will mean more body fat loss versus LBM.
- Adequate protein intake (see http://ajcn.nutrition.org/content/103/3/738.full)
- Presence or lack of muscle stimulus - Strength type exercise being touted as muscle sparing.
- The severity of the deficit - Steeper deficit will tilt the ratio of LBM/Fat loss towards the LBM
- Genetics - I assume (but I'm prepared to be wrong) that some people are genetically predisposed to retain more muscle in a loss situation than others.
Why would the body use muscle in the first place and not just burn off the fat? I think you've got it right in your original post, muscle is energetically expensive and in times of low food input the body will attempt to reduce energy consumption by making you move less (lethargy and reduction of NEAT) and by reduction in the energy overhead associated with muscle.
In my unscientific opinion, this is correct. Although I would argue that severity of the deficit only comes in to play when an individual is lean already. A large deficit when you have a high bodyfat percentage isn't really an issue.
Ah now, that's interesting. So the ratio lost could correlate with the original muscle/fat numbers, that would seem logical.
I'd always thought that if the body was storing surplus energy as fat, then why wouldn't it just reduce that fat in times of deficit as apposed to muscle which presumably takes more energy.
So, in my case (with high BF) I could probably eat at a higher deficit (assuming it's sustainable, adequate nutrition etc,) continue lifting heavy and probably suffer minimal muscle loss until my BF% was to drop.
I won't, there's no point if it's not sustainable and I'm happy with my progress, just curious really.
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Good question . I have wondering same thing .. thanks for answers and good luck everyone1
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Thanks all, it makes sense to me, just something I'd wondered about.trigden1991 wrote: »StealthHealth wrote: »My, somewhat non-scientific, understanding is this.
Ratio of fat/LBM loss in caloric deficit will depend upon:- Existing Fat/LBM composition - where more body fat will mean more body fat loss versus LBM.
- Adequate protein intake (see http://ajcn.nutrition.org/content/103/3/738.full)
- Presence or lack of muscle stimulus - Strength type exercise being touted as muscle sparing.
- The severity of the deficit - Steeper deficit will tilt the ratio of LBM/Fat loss towards the LBM
- Genetics - I assume (but I'm prepared to be wrong) that some people are genetically predisposed to retain more muscle in a loss situation than others.
Why would the body use muscle in the first place and not just burn off the fat? I think you've got it right in your original post, muscle is energetically expensive and in times of low food input the body will attempt to reduce energy consumption by making you move less (lethargy and reduction of NEAT) and by reduction in the energy overhead associated with muscle.
In my unscientific opinion, this is correct. Although I would argue that severity of the deficit only comes in to play when an individual is lean already. A large deficit when you have a high bodyfat percentage isn't really an issue.
Ah now, that's interesting. So the ratio lost could correlate with the original muscle/fat numbers, that would seem logical.
I'd always thought that if the body was storing surplus energy as fat, then why wouldn't it just reduce that fat in times of deficit as apposed to muscle which presumably takes more energy.
So, in my case (with high BF) I could probably eat at a higher deficit (assuming it's sustainable, adequate nutrition etc,) continue lifting heavy and probably suffer minimal muscle loss until my BF% was to drop.
I won't, there's no point if it's not sustainable and I'm happy with my progress, just curious really.
Your plan sounds spot on to me. Remember that as you get lighter and leaner, your maintenance calories (TDEE) will be lower so to keep the deficit high you will need to reduce your calories further.2 -
trigden1991 wrote: »Thanks all, it makes sense to me, just something I'd wondered about.trigden1991 wrote: »StealthHealth wrote: »My, somewhat non-scientific, understanding is this.
Ratio of fat/LBM loss in caloric deficit will depend upon:- Existing Fat/LBM composition - where more body fat will mean more body fat loss versus LBM.
- Adequate protein intake (see http://ajcn.nutrition.org/content/103/3/738.full)
- Presence or lack of muscle stimulus - Strength type exercise being touted as muscle sparing.
- The severity of the deficit - Steeper deficit will tilt the ratio of LBM/Fat loss towards the LBM
- Genetics - I assume (but I'm prepared to be wrong) that some people are genetically predisposed to retain more muscle in a loss situation than others.
Why would the body use muscle in the first place and not just burn off the fat? I think you've got it right in your original post, muscle is energetically expensive and in times of low food input the body will attempt to reduce energy consumption by making you move less (lethargy and reduction of NEAT) and by reduction in the energy overhead associated with muscle.
In my unscientific opinion, this is correct. Although I would argue that severity of the deficit only comes in to play when an individual is lean already. A large deficit when you have a high bodyfat percentage isn't really an issue.
Ah now, that's interesting. So the ratio lost could correlate with the original muscle/fat numbers, that would seem logical.
I'd always thought that if the body was storing surplus energy as fat, then why wouldn't it just reduce that fat in times of deficit as apposed to muscle which presumably takes more energy.
So, in my case (with high BF) I could probably eat at a higher deficit (assuming it's sustainable, adequate nutrition etc,) continue lifting heavy and probably suffer minimal muscle loss until my BF% was to drop.
I won't, there's no point if it's not sustainable and I'm happy with my progress, just curious really.
Your plan sounds spot on to me. Remember that as you get lighter and leaner, your maintenance calories (TDEE) will be lower so to keep the deficit high you will need to reduce your calories further.
Thanks for that, much appreciated.
At the moment, I use the MFP TDEE figure with my Garmin activity tracker linked to it. I weigh daily on a trending app, but log weekly on here which then allows MFP to recalculate TDEE if required. (I assume that's what it does!)
That way I get a fix on how the week has gone and whether it ties up with projected fat loss.
So far, I'm actually losing a bit quicker, goal is 1.5lb/week but I'm actually averaging 2 - 2.5lb/week (I have a lot to lose) but I do try and allow a couple of hundred calories float at the end of the day, preferably under target.
I know it sounds a bit slack, but I usually have IRO 2400-2600 calorie daily allowance so a couple of hundred calories is a smaller percentage than it sounds (I know I'll need to tighten up a lot more as it drops and I get closer to goal)
Does that sound like a good approach to you? Just keep on allowing MFP/Garmin to do the calculation and cross check it with weight lost? Or should I be a bit more pro-active with it?
1 -
And what sort of ratio to fat is it? Or does that vary wildly according to genetics/working out/protein intake etc.
Why does the body lose muscle at all, is it just easier to metabolise than fat, or is it stripped off as it's too "expensive" for the body to maintain when it's in calorific deficit?
I'm purely asking out of interest, I'm at a small deficit, keeping my protein up and lifting regularly, just curious as to what I'll lose and why! (if it's even answerable)
Think of muscle as a commodity...an expensive one...it requires a good deal of energy to maintain that commodity...when you diet you are depriving your body of energy. Yes, fat is going to make up much of the difference, but from an evolutionary standpoint, using that backup energy for essential functions is going to be more important than using it to preserving muscle mass, especially if it's not really being utilized.
In that regard, it's also a use it or lose it proposition...again, it's an expensive commodity for your body to maintain...you don't use it and you're depriving your body of energy...it is more efficient for your body to just unload some of this expensive commodity. When you provide stimulus and use it, your body recognizes that it's important and will divert resources to preserve it...at least more of it.
The ratio is going to depend on a number of factors which were laid out pretty well above.
2 -
trigden1991 wrote: »Thanks all, it makes sense to me, just something I'd wondered about.trigden1991 wrote: »StealthHealth wrote: »My, somewhat non-scientific, understanding is this.
Ratio of fat/LBM loss in caloric deficit will depend upon:- Existing Fat/LBM composition - where more body fat will mean more body fat loss versus LBM.
- Adequate protein intake (see http://ajcn.nutrition.org/content/103/3/738.full)
- Presence or lack of muscle stimulus - Strength type exercise being touted as muscle sparing.
- The severity of the deficit - Steeper deficit will tilt the ratio of LBM/Fat loss towards the LBM
- Genetics - I assume (but I'm prepared to be wrong) that some people are genetically predisposed to retain more muscle in a loss situation than others.
Why would the body use muscle in the first place and not just burn off the fat? I think you've got it right in your original post, muscle is energetically expensive and in times of low food input the body will attempt to reduce energy consumption by making you move less (lethargy and reduction of NEAT) and by reduction in the energy overhead associated with muscle.
In my unscientific opinion, this is correct. Although I would argue that severity of the deficit only comes in to play when an individual is lean already. A large deficit when you have a high bodyfat percentage isn't really an issue.
Ah now, that's interesting. So the ratio lost could correlate with the original muscle/fat numbers, that would seem logical.
I'd always thought that if the body was storing surplus energy as fat, then why wouldn't it just reduce that fat in times of deficit as apposed to muscle which presumably takes more energy.
So, in my case (with high BF) I could probably eat at a higher deficit (assuming it's sustainable, adequate nutrition etc,) continue lifting heavy and probably suffer minimal muscle loss until my BF% was to drop.
I won't, there's no point if it's not sustainable and I'm happy with my progress, just curious really.
Your plan sounds spot on to me. Remember that as you get lighter and leaner, your maintenance calories (TDEE) will be lower so to keep the deficit high you will need to reduce your calories further.
Thanks for that, much appreciated.
At the moment, I use the MFP TDEE figure with my Garmin activity tracker linked to it. I weigh daily on a trending app, but log weekly on here which then allows MFP to recalculate TDEE if required. (I assume that's what it does!)
That way I get a fix on how the week has gone and whether it ties up with projected fat loss.
So far, I'm actually losing a bit quicker, goal is 1.5lb/week but I'm actually averaging 2 - 2.5lb/week (I have a lot to lose) but I do try and allow a couple of hundred calories float at the end of the day, preferably under target.
I know it sounds a bit slack, but I usually have IRO 2400-2600 calorie daily allowance so a couple of hundred calories is a smaller percentage than it sounds (I know I'll need to tighten up a lot more as it drops and I get closer to goal)
Does that sound like a good approach to you? Just keep on allowing MFP/Garmin to do the calculation and cross check it with weight lost? Or should I be a bit more pro-active with it?
That's fine for now but as you get lighter and it is harder to lose, the more accurate you will need to be.
I calculate my own TDEE weekly by looking at calories consumed and weight lost.2 -
cwolfman13 wrote: »And what sort of ratio to fat is it? Or does that vary wildly according to genetics/working out/protein intake etc.
Why does the body lose muscle at all, is it just easier to metabolise than fat, or is it stripped off as it's too "expensive" for the body to maintain when it's in calorific deficit?
I'm purely asking out of interest, I'm at a small deficit, keeping my protein up and lifting regularly, just curious as to what I'll lose and why! (if it's even answerable)
Think of muscle as a commodity...an expensive one...it requires a good deal of energy to maintain that commodity...when you diet you are depriving your body of energy. Yes, fat is going to make up much of the difference, but from an evolutionary standpoint, using that backup energy for essential functions is going to be more important than using it to preserving muscle mass, especially if it's not really being utilized.
In that regard, it's also a use it or lose it proposition...again, it's an expensive commodity for your body to maintain...you don't use it and you're depriving your body of energy...it is more efficient for your body to just unload some of this expensive commodity. When you provide stimulus and use it, your body recognizes that it's important and will divert resources to preserve it...at least more of it.
The ratio is going to depend on a number of factors which were laid out pretty well above.
Thanks for that, it really is a win-win with the heavy lifting then.
Preserve muscle which helps raise TDEE, and you look better, and are stronger at goal. Perfect!1 -
trigden1991 wrote: »trigden1991 wrote: »Thanks all, it makes sense to me, just something I'd wondered about.trigden1991 wrote: »StealthHealth wrote: »My, somewhat non-scientific, understanding is this.
Ratio of fat/LBM loss in caloric deficit will depend upon:- Existing Fat/LBM composition - where more body fat will mean more body fat loss versus LBM.
- Adequate protein intake (see http://ajcn.nutrition.org/content/103/3/738.full)
- Presence or lack of muscle stimulus - Strength type exercise being touted as muscle sparing.
- The severity of the deficit - Steeper deficit will tilt the ratio of LBM/Fat loss towards the LBM
- Genetics - I assume (but I'm prepared to be wrong) that some people are genetically predisposed to retain more muscle in a loss situation than others.
Why would the body use muscle in the first place and not just burn off the fat? I think you've got it right in your original post, muscle is energetically expensive and in times of low food input the body will attempt to reduce energy consumption by making you move less (lethargy and reduction of NEAT) and by reduction in the energy overhead associated with muscle.
In my unscientific opinion, this is correct. Although I would argue that severity of the deficit only comes in to play when an individual is lean already. A large deficit when you have a high bodyfat percentage isn't really an issue.
Ah now, that's interesting. So the ratio lost could correlate with the original muscle/fat numbers, that would seem logical.
I'd always thought that if the body was storing surplus energy as fat, then why wouldn't it just reduce that fat in times of deficit as apposed to muscle which presumably takes more energy.
So, in my case (with high BF) I could probably eat at a higher deficit (assuming it's sustainable, adequate nutrition etc,) continue lifting heavy and probably suffer minimal muscle loss until my BF% was to drop.
I won't, there's no point if it's not sustainable and I'm happy with my progress, just curious really.
Your plan sounds spot on to me. Remember that as you get lighter and leaner, your maintenance calories (TDEE) will be lower so to keep the deficit high you will need to reduce your calories further.
Thanks for that, much appreciated.
At the moment, I use the MFP TDEE figure with my Garmin activity tracker linked to it. I weigh daily on a trending app, but log weekly on here which then allows MFP to recalculate TDEE if required. (I assume that's what it does!)
That way I get a fix on how the week has gone and whether it ties up with projected fat loss.
So far, I'm actually losing a bit quicker, goal is 1.5lb/week but I'm actually averaging 2 - 2.5lb/week (I have a lot to lose) but I do try and allow a couple of hundred calories float at the end of the day, preferably under target.
I know it sounds a bit slack, but I usually have IRO 2400-2600 calorie daily allowance so a couple of hundred calories is a smaller percentage than it sounds (I know I'll need to tighten up a lot more as it drops and I get closer to goal)
Does that sound like a good approach to you? Just keep on allowing MFP/Garmin to do the calculation and cross check it with weight lost? Or should I be a bit more pro-active with it?
That's fine for now but as you get lighter and it is harder to lose, the more accurate you will need to be.
I calculate my own TDEE weekly by looking at calories consumed and weight lost.
I shall do the same then! Thanks for your help, much appreciated.1 -
trigden1991 wrote: »trigden1991 wrote: »Thanks all, it makes sense to me, just something I'd wondered about.trigden1991 wrote: »StealthHealth wrote: »My, somewhat non-scientific, understanding is this.
Ratio of fat/LBM loss in caloric deficit will depend upon:- Existing Fat/LBM composition - where more body fat will mean more body fat loss versus LBM.
- Adequate protein intake (see http://ajcn.nutrition.org/content/103/3/738.full)
- Presence or lack of muscle stimulus - Strength type exercise being touted as muscle sparing.
- The severity of the deficit - Steeper deficit will tilt the ratio of LBM/Fat loss towards the LBM
- Genetics - I assume (but I'm prepared to be wrong) that some people are genetically predisposed to retain more muscle in a loss situation than others.
Why would the body use muscle in the first place and not just burn off the fat? I think you've got it right in your original post, muscle is energetically expensive and in times of low food input the body will attempt to reduce energy consumption by making you move less (lethargy and reduction of NEAT) and by reduction in the energy overhead associated with muscle.
In my unscientific opinion, this is correct. Although I would argue that severity of the deficit only comes in to play when an individual is lean already. A large deficit when you have a high bodyfat percentage isn't really an issue.
Ah now, that's interesting. So the ratio lost could correlate with the original muscle/fat numbers, that would seem logical.
I'd always thought that if the body was storing surplus energy as fat, then why wouldn't it just reduce that fat in times of deficit as apposed to muscle which presumably takes more energy.
So, in my case (with high BF) I could probably eat at a higher deficit (assuming it's sustainable, adequate nutrition etc,) continue lifting heavy and probably suffer minimal muscle loss until my BF% was to drop.
I won't, there's no point if it's not sustainable and I'm happy with my progress, just curious really.
Your plan sounds spot on to me. Remember that as you get lighter and leaner, your maintenance calories (TDEE) will be lower so to keep the deficit high you will need to reduce your calories further.
Thanks for that, much appreciated.
At the moment, I use the MFP TDEE figure with my Garmin activity tracker linked to it. I weigh daily on a trending app, but log weekly on here which then allows MFP to recalculate TDEE if required. (I assume that's what it does!)
That way I get a fix on how the week has gone and whether it ties up with projected fat loss.
So far, I'm actually losing a bit quicker, goal is 1.5lb/week but I'm actually averaging 2 - 2.5lb/week (I have a lot to lose) but I do try and allow a couple of hundred calories float at the end of the day, preferably under target.
I know it sounds a bit slack, but I usually have IRO 2400-2600 calorie daily allowance so a couple of hundred calories is a smaller percentage than it sounds (I know I'll need to tighten up a lot more as it drops and I get closer to goal)
Does that sound like a good approach to you? Just keep on allowing MFP/Garmin to do the calculation and cross check it with weight lost? Or should I be a bit more pro-active with it?
That's fine for now but as you get lighter and it is harder to lose, the more accurate you will need to be.
I calculate my own TDEE weekly by looking at calories consumed and weight lost.
I shall do the same then! Thanks for your help, much appreciated.
Not a problem man. Best of luck1
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