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PostPosted: Tue May 20, 2008 11:36 pm 
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As I understand it, your body doesn't burn stored bodyfat to build muscle. Except for beginners and de-trained people, you either get a caloric deficit and burn fat (assuming a proper diet/training plan) or a caloric surplus and build muscle (assuming a proper diet/training plan again).

My question is - why doesn't the body respond to a muscle-building workout by burning stored bodyfat to "fund" muscle growth? Why do you essentially store the fat until you dedicate some time to burning it off and generally maintain strength?

I understand that this doesn't happen, muscle doesn't "turn into" fat or vice-versa...what I don't understand is the technical/biological "why" of it. Is it that the body's survival mechanism prioritizes stored fat for emergency energy over muscle growth? Is it that stored fat doesn't have the complete proteins or aminos or whatever to build muscle, so it can't be used for that?

I realized recently that I know what occurs and what doesn't, but that I don't truly understand why this is the case. Can someone explain in relatively simple terms?

Thanks,

Peter


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PostPosted: Wed May 21, 2008 12:41 pm 
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Fat is ultimately oxidized into acetyl-CoA that can enter into the Krebs Cycle for energy (ATP) production. Basically, as you said, fat doesn’t have the required components for protein synthesis. Fat is an energy cell not a building block. This is true of both ingested and stored fat.

Think of it this way, you can start a fire with gas or wood......but of those two, you can only build a house out of the wood.


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PostPosted: Wed May 21, 2008 1:14 pm 
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Obviously fat can not build muscle directly. You need protein and carbs.

If you can stimulate your muscles intensly enough, you can convince your body that you need to conserve muscle or even build it while losing fat. The trouble as I see it, is that if you don't have enough energy in the form of carbs and protein at the time of the activity and during the key 24 hour period after, you probably won't be able to build muscle. It's hard to do that while you're in a calorie deficit.

It you are extremely precise in your nutrient intake with proper timing, I think it's possible to do both at the same time. Alwyn Cosgrove has shown that it's possible to lose 4-5 lbs a week while maintaing ALL of your muscle. I've seen some people gain muscle on his program although they were detrained. I would think that you could vary his program slightly and achieve a significant consecutive fat loss and muscle gain but it would be a significant balancing act. If you could get it to work consistently, you could probably write a book and make a fortune.

It's probably easier to just carb cycle. Eat more on workout days and less on the off days.

Stu


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PostPosted: Wed May 21, 2008 3:52 pm 
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@pdellorto:

Bodyfat is a slow burning, long lasting fuel that is not suited for strength training. The only way to use bodyfat as fuel is either through endurance training or dieting.

Bodyfat accumulation is an artifact of the pre-agricultural days when starvation was a serious day to day problem for people. These days, however, bodyfat accumulation itself is the problem - most people have more than enough to eat.


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PostPosted: Wed May 21, 2008 7:33 pm 
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Okay, that makes a lot of sense. It's the wrong fuel for the job and doesn't have the materials necessary to accomplish the job. That would explain why it's so hard to do both.

Thanks guys, that helps me wrap my head around the "why."


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PostPosted: Wed May 21, 2008 7:36 pm 
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"The only way to use bodyfat as fuel is either through endurance training or dieting."

I have to disagree with you Stephen, or maybe it is just a matter of symantics. I hate doing this without having the actual studies to quote from, but everything I have been reading lately is that resistance training is actually good for fat loss. The reasoning being that aerobic training primarily raises the metabolism only during the duration of the event. Resistance training doesn't give you as high of a spike in metabolism but the sustained rise in metabolism due to the bodies need to repair itself can be greater.

So it can't be used for muscle growth but can aid in energy needs.

This isn't saying that endurance training is bad or that weight training is better. As I said earlier, it might just be a matter of symantics.


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PostPosted: Wed May 21, 2008 8:47 pm 
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hoosegow wrote:
So it can't be used for muscle growth but can aid in energy needs.


That would explain why intense anaerobic exercise helps burn fat. When I try to burn fat I do metcons and complexes and heavy lifting, but eat less in the hopes of having my body burned stored fat.

When I try to bulk, I do metcons and complexes and heavy lifting and eat more. Heh. Clearly I've got a one-track mind.

(By the way guys, apologies for the grammar in the title, the character limit was too short for "doesn't." As an English teacher it pains me a bit but it had to be done).


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PostPosted: Wed May 21, 2008 10:37 pm 
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hoosegow wrote:
"The only way to use bodyfat as fuel is either through endurance training or dieting."

I have to disagree with you Stephen, or maybe it is just a matter of symantics. I hate doing this without having the actual studies to quote from, but everything I have been reading lately is that resistance training is actually good for fat loss. The reasoning being that aerobic training primarily raises the metabolism only during the duration of the event. Resistance training doesn't give you as high of a spike in metabolism but the sustained rise in metabolism due to the bodies need to repair itself can be greater.

So it can't be used for muscle growth but can aid in energy needs.

This isn't saying that endurance training is bad or that weight training is better. As I said earlier, it might just be a matter of symantics.


You have a point - weight training will cause a modest bump in your metabolism. But if your body's energy needs increase and your caloric intake doesn't match it, guess what? - You're dieting! :wink:

Like you said, it's just a matter of semantics. But it was worth bringing up. Thanks.


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PostPosted: Wed May 21, 2008 10:54 pm 
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hoosegow wrote:
"The only way to use bodyfat as fuel is either through endurance training or dieting."

I have to disagree with you Stephen, or maybe it is just a matter of symantics. I hate doing this without having the actual studies to quote from, but everything I have been reading lately is that resistance training is actually good for fat loss. The reasoning being that aerobic training primarily raises the metabolism only during the duration of the event. Resistance training doesn't give you as high of a spike in metabolism but the sustained rise in metabolism due to the bodies need to repair itself can be greater.

So it can't be used for muscle growth but can aid in energy needs.

This isn't saying that endurance training is bad or that weight training is better. As I said earlier, it might just be a matter of symantics.


You speak of EPOC: Excess Post-exercise Oxygen Consumption. It's the state your body enters after heavy exercise. Both aerobic and anaerobic exercise can cause this, but studies show that anaerobic exercise increases the EPOC effect far more.

Here's a quick Wiki article that sums it up.

http://en.wikipedia.org/wiki/Excess_pos ... onsumption


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PostPosted: Thu May 22, 2008 5:03 am 
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In terms of EPOC - I've not seen the studies myself, but the sources are widely trusted - Cosgrove, Berardi etc.

The elevation in metabolism is supposed to last about 36 hours... I've seen many different numbers, but 36 hours is the one you see most. The general concept is clear when you start doing anaerobic activity - your appetite shoots up.

KPj


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PostPosted: Thu May 22, 2008 6:34 am 
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Was doing some lunch time browsing, thought I would post this, from,

http://alwyncosgrove.blogspot.com/2006/ ... ffect.html

Quote:
Schuenke MD, Mikat RP, McBride JM.
Effect of an acute period of resistance exercise on excess post-exercise oxygen consumption (EPOC): implications for body fat management.
Eur J Appl Physiol 2002 Mar;86(5):411-7

This group looked at the effects of circuit weight training on EPOC.

The exercise routine consisted of three exercises (the bench press, the power clean and the squat), performed with 10RM loads as a circuit. The circuit was performed four times (i.e. twelve total sets) and took 31 mins.

EPOC was elevated for 38 hours post workout (possibly longer as this was when the researchers stopped measuring). The duration and magnitude of the EPOC observed in this study indicates the importance of the role of high intensity resistance training in a fat loss program.


Also, a quote I picken up on the PN forums which i really like,

Quote:
"Caring how much fat is burned during training makes as much sense as caring how much muscle is built during training."


KPj


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PostPosted: Thu May 22, 2008 4:28 pm 
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KPj wrote:
EPOC was elevated for 38 hours post workout


This study doesn't say how much EPOC was elevated. Apparently it's not a lot and although it lasts a long time it goes down quickly. Most is in the first hour and then declines. Overall there is a significant effect but it's not huge.


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