# Which Burns First, Fat or Muscle?



## trodizzle (Nov 13, 2015)

*Last Updated:* 06-28-2015
*Author:* Meredith Crilly
*Background: *Meredith C. has worked as a nutrition educator, chef and community health projects since 2011. She received a Bachelor of Science in nutrition from the University of Tennessee and is currently completing an MS/DI program in nutrition.
*References:*
Texas A&M University: Integration of Metabolism
Biochemistry, Fifth Edition; J. M. Berg, J. L Tymoczko, L. Stryer
University of Montana: Eat for Performance

*Article:*

Whether you're training for an event, trying to increase your muscle mass or just want to get in better shape, your body relies on three main nutrients for fuel. Because your body can break down carbohydrates, muscle and fat for energy, understanding the order of nutrient breakdown can help you save or build muscle mass and increase fat loss.

*Primarily Carbohydrates*
The first fuel that your body breaks down for energy is carbohydrates. After a meal, your body is in the "fed" state and preferentially breaks down carbohydrates since they are easily accessible and turned into energy. After your body has used up the carbohydrates from a meal or snack, your cells begin to break down glucose stored in your muscles and liver known as glycogen. Glycogen stores vary in each person, but are typically depleted within 24 hours, meaning your body has to begin breaking down other compounds for energy.

*Fat Preferentially Metabolized*
When glucose and glycogen are not available, your body preferentially breaks down fatty compounds known as triacylglycerols which are present in adipose or fat tissue. Because fat is a high-energy source with nine calories per gram, fat provides an efficient fuel source. Additionally, your body metabolically prefers to preserve lean body mass and, when possible, breaks down fat stores for fuel as much as possible. Only when your fat stores are extremely low or depleted does your body have to then break down protein.

*Muscle Breakdown*
When glucose and fat stores are depleted, your body will then turn to muscle to break down into individual amino acids for energy. Unlike carbohydrates and fat, your body does not store amino acids, which is why muscle breakdown is the only way to release amino acids for fuel. In typical conditions where you are eating on a regular basis, your body will not use muscle for energy. Typically, protein is used for fuel only in a starvation state. Because you need muscle tissue to survive and move, the natural tendency of metabolism is to spare muscle tissue and break down carbohydrates and fat first.

*Other Considerations*
While your body avoids breaking down muscle tissue, an inadequate diet prevents muscle gains. Although you may be working out and trying to gain muscle mass, if you are not following a diet adequate in protein and calories, your body will not build muscle cells and you may even notice muscle losses. If you are not eating adequate protein, the muscle damage that occurs during exercise cannot be fixed and muscle size or strength may decrease. Without adequate replenishment, you may think your body is breaking down muscle when instead, your cells lack the nutrients needed to repair and rebuild. If you are trying to gain muscle mass or increase your overall strength, consult with a dietitian and trainer to build a healthy, balanced diet that will help you reach your goals.


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## ToolSteel (Nov 13, 2015)

Is there a similar study done on super physiological levels of muscle mass?


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## trodizzle (Nov 13, 2015)

ToolSteel said:


> Is there a similar study done on super physiological levels of muscle mass?



Not that I have found, but I doubt there is some sort of line that when crossed (in regards to x levels of muscle mass) when your body starts working differently. It seems more logical that the processes of the human body would still continue to function the same way, using carbs first, then fats, then muscle mass (if fed properly) even if you were all jacked up like Yaya.


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## Uncle manny (Nov 13, 2015)

Nice little read


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## tunafisherman (Nov 13, 2015)

So what you are saying is that the obese people aren't out of shape, they are just fully fueled fighting machines waiting to unleash energy like the atom bomb right?? haha


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## stonetag (Nov 13, 2015)

I believe it's pretty well known that your body prefers to save lean muscle for the last supper.


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## PillarofBalance (Nov 13, 2015)

Hmmm...

I think your primary energy source depends on how your train; aerobic or anaerobic.  Fat for aerobic and glycogen for anaerobic primarily. 

The body is less likely to use muscle for energy first if training stress is significant to the muscle. Give your body the sign that you NEED that muscle and it will prioritize.


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## DieYoungStrong (Nov 13, 2015)

tunafisherman said:


> So what you are saying is that the obese people aren't out of shape, they are just fully fueled fighting machines waiting to unleash energy like the atom bomb right?? haha



It's like I tell my wife..."This isn't a gut. It's fuel for a sex machine!"


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## trodizzle (Nov 13, 2015)

PillarofBalance said:


> Hmmm...
> 
> I think your primary energy source depends on how your train; aerobic or anaerobic.  Fat for aerobic and glycogen for anaerobic primarily.
> 
> The body is less likely to use muscle for energy first if training stress is significant to the muscle. Give your body the sign that you NEED that muscle and it will prioritize.



Any docs or articles to back this up my ginger friend?


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## DocDePanda187123 (Nov 13, 2015)

trodizzle said:


> Any docs or articles to back this up my ginger friend?



That's why you lift during a cut, the stress if weightlifting will stimulate the muscle and help retain it. Cortisol also plays a huge role in what source of energy your body will use.


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## PillarofBalance (Nov 14, 2015)

trodizzle said:


> Any docs or articles to back this up my ginger friend?



Facts already in evidence I believe. Read any anatomy and physiology text. 

Fats > Fatty Acids > AcetylCoA > Citric Acid Cycle yada yada yada







Glycolosis can occur in the absence of oxygen.

This video explains fatty acid metabolism pretty well

https://www.youtube.com/watch?v=acA5iF1zrDI&list=PLbKSbFnKYVY0IFIZQsDo8ZfAq8oq8cgxg&index=6


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## widehips71 (Nov 14, 2015)

PillarofBalance said:


> Facts already in evidence I believe. Read any anatomy and physiology text.
> 
> Fats > Fatty Acids > AcetylCoA > Citric Acid Cycle yada yada yada
> 
> ...



You just turned jizzles world upside down. Poor guy has no idea what he's looking at


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## don draco (Nov 14, 2015)

Muscle will be the last thing to go, even in a state of starvation.  Proteins serve vital functions in the body, so even skeletal muscle proteolysis is curtailed until other energy-producing pathways such as glycolysis, the TCA cycle and beta oxidation are unable to proceed further. From an evolutionary and survival standpoint, it only makes sense -- if muscle tissue were degraded at the same rate as glucose or fatty acids, the organism would not only experience a decrease in efficiency of vital bodily functions necessary for survival, but it would also lack the muscle mass necessary to provide for itself in its environment. The body employs several mechanisms to protect muscle cells due to the vital role they play in the body.  

However, this does raise the question of whether the added muscle from resistance training is more prone to premature skeletal muscle proteolysis because of the chance that it is deemed physiologically unnecessary.  I am unsure whether the degradation sequence truly applies to those who have added more muscle to their frames than they would carry in their natural, untrained state.  This could also explain why it's extremely important to continue resistance training when in a caloric deficit -- the body needs a stimulus to "convince" it that the added calorie-consuming muscle mass is necessary for its survival.  

If any of you would like to read more about this topic, check out this publication. It's interesting stuff. 

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3775123/


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## GSgator (Nov 15, 2015)

Ya I dont  find that so true I'm sure we have all tried to get really shredded and in the process if not careful you can litterally melt away so much hard earned  muscle before even getting close to the desired look or fat %.. I've learned that the hard way on a couple of my first cutters I think there's alot of Variables to consider. I skipped over your post don and read it after making my post it makes total since.


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## rburdge84 (Nov 22, 2015)

This made me chuckle.

Too much crap flies around and people believe it.

It was said correct before. Your body burns combination of all fuel types depending what intensity you are at. At rest and mostly aerobic exercise the biggest fuel to the fire is fat but once your body is anerobic it kicks into almost all carbs with small percentage of fat. The only time you burn muscle is when you cut carbs completely for long periods of time and when your an endurance athletes.


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## AjSam (Nov 22, 2015)

Very good information, great read.


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## Coldblooded (Sep 17, 2018)

tunafisherman said:


> So what you are saying is that the obese people aren't out of shape, they are just fully fueled fighting machines waiting to unleash energy like the atom bomb right?? haha



That is possibly the best reasoning I've heard in a long time!!


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