The difference between burning muscle and fat

[PennState]

Well i want to start off this post by saying THANKS to whoever made this possible. This is actually my first post in a long time on the teen section. Just b/c everything i wrote got over ran with easier to answer questions.


Ok so here goes. I am cutting right now and trying to understand why exactly my body burns fat and not muscle. The body uses fat as stored energy and we have muscle to give us strength so we can do the work that is necessary in every day life. Well for bodybuilders we basically fool our body into thinking it needs lots of muscle to move lots of weight. But beyond that why when cutting do i have to be scared of loosing muscle. When in calorie deficiet should my body automatically burn fat? But that isn't true, b/c if i was to stop eating i would burn muscle right? So what is the difference between being catabolic in a good sense (burning fat) or being it in a bad sense (burning muscle)? Once we figure out when our bodies do this, sholdn't it be easier to manipulate the body to burn the most fat possible?

Perhaps this is just me rambling about fat loss. But i would like to know this difference. I just don't understand why when i do cardio the body burns calories and ups my metabolism and i don't loose muscle. But when i starve myself i'm going to loose all sorts of muscle. I know that my body thinks it is starving to death when i fast, but shouldn't it still want to burn the fat first? Since that is going to be longer term energy? And i still am faking the body into thinking i need the muscle with lifting daily.

Confusion...


All that aside i am cutting and loosing fat w/o loosing muscle (showing in BF% dropping ) and i'm loosing it slow 1-2 lbs a week. And things are going well. I just want to know this for my own peace of mind.

[LikeICare]

Well i want to start off this post by saying THANKS to whoever made this possible. .

oscar?

[PennState]

oscar?

nope...MTV video music award

[Peter Mundy]

The catabolic stage is when glycogen and fat are being depleted, but the catabolic state everyone fears is when glycogen and fat stores have run out resulting in musculer wastage.

Because muscle have no glycogen or fat to use for energy when starving yourself the once the body has finished with fat stores from our yellow bone marrow the only thing we can do is burn muscle for energy for our body to keep moving...

The best thing for you to do is simply perform cardio, lots of cardio. Then replenish glycogen and protien stores after hard cardio.

Don't know if any of thsi actually helped but i tried, your questions kind of confused me.

[the_kid]

Ok so here goes. I am cutting right now and trying to understand why exactly my body burns fat and not muscle. The body uses fat as stored energy and we have muscle to give us strength so we can do the work that is necessary in every day life. Well for bodybuilders we basically fool our body into thinking it needs lots of muscle to move lots of weight. But beyond that why when cutting do i have to be scared of loosing muscle. When in calorie deficiet should my body automatically burn fat? But that isn't true, b/c if i was to stop eating i would burn muscle right? So what is the difference between being catabolic in a good sense (burning fat) or being it in a bad sense (burning muscle)? Once we figure out when our bodies do this, sholdn't it be easier to manipulate the body to burn the most fat possible?

It comes down to a few variables - overall nutrition, training intensity, and conditioning of the individual come to mind immediately.

If you have a sound nutrition plan that compensates for your daily activities and goals, muscle loss should be kept to a minimum.

Training intensity will determine the primary energy pathway utilized by the body during training. High intensity is more anaerobic glycolytic and will use carbs mainly as fuel (glycogen, blood glucose). While low intensity is aerobic oxidative and will rely upon fats as the primary energy source. If one were to perform high intensity training without sufficient carbs (ingested or stored), the body will look elsewhere for immediate energy. This is when gluconeogenesis can take place as beta oxidation will likely not be able to keep up with the energy demands.

Specific conditioning may also determine the individual's primary energy source and fat burning efficiency. Those who train aerobics regularly and who have a good amount of red fibers will likely be more efficient at mobilizing and utilizing FFAs than those who predominantly train anaerobically and who have higher white fiber counts.


Good nutrition that compensates for training intensity = minimal muscle loss.

Perhaps this is just me rambling about fat loss. But i would like to know this difference. I just don't understand why when i do cardio the body burns calories and ups my metabolism and i don't loose muscle. But when i starve myself i'm going to loose all sorts of muscle. I know that my body thinks it is starving to death when i fast, but shouldn't it still want to burn the fat first? Since that is going to be longer term energy? And i still am faking the body into thinking i need the muscle with lifting daily.

Basically fasting equals no energy input into the body. Since the body relies upon glucose to perform vital tasks (not to mention feeding the brain), it will need to manufacture glucose from other compounds (gluconeogenesis). Amino acids and glycerol from triglycerides readily convert to glucose. Keep in mind that glucose is also needed to fuel gluconeogenesis and the Krebs cycle. Fat oxidation will still take place (depending on how much fat you have), but whether or not it will outweigh protein degradation in a fasting state I am unsure of.

[InTeNsIFieR]

Adipose tissue lipolysis tends to stay constant (From 3rd day to 40th day of starvation), while muscle protein degradation tends to decrease as the starvation goes on, to ensure the survival of the organism.

Why does it decrease?

Because as the starvation goes on ketone bodies become the major fuel of the brain. The conversion of fatty acids into ketone bodies (by the liver) and the use of ketone bodies by the brain reduces the need for glucose. So less muscle muscle protein degradation occurs within the body.

[irishbuilder]

Adipose tissue lipolysis tends to stay constant (From 3rd day to 40th day of starvation), while muscle protein degradation tends to decrease as the starvation goes on, to ensure the survival of the organism.

Why does it decrease?

Because as the starvation goes on ketone bodies become the major fuel of the brain. The conversion of fatty acids into ketone bodies (by the liver) and the use of ketone bodies by the brain reduces the need for glucose. So less muscle muscle protein degradation occurs within the body.

good post.

[Guardian]

The only real seperation is heart rate and energy levels. Heart rates to high will automattically trigger muscles to be used for energy. They sell heart moniters, although I dont know the exact levels, you can research into it and find it.

[BigTruckGuy3500]

Ok, if I understand your question correctly I'll try and answer it.

If you were simply in a caloric deficit your body would use a combination of fat and muscle for fuel. Almost at 50/50, excluding carbs. But when you lift weights you cause microtears and tension stimulus in your muscles. So your body therefore must repair and try and compensate for the tension in your muscles, thus repairing them. But since you're in a caloric deficit your body can only repair it to a certain extent.

And like someone said, absolute starvation leads to a lot of muscle loss and very little fat loss because your body thinks having fat stores will most likely help you survive more than having muscle. Also as your calories decrease your body creates higher levels of "bad" hormones, and less "good" ones.

[Gibblets]

There seems to be a lot of good answers here but i'm not really sure if they answer what he's asking. Without having the scientific terms for everything I think I know what he's asking.

Your body knows muscle is expendable. Stored fat is there incase your body needs to survive in starvation mode, and it is the body's last line of defense before the need to digest organs. Muscle however, is not the last line of defense, and if you were starving yourself your body would target the muscle first, knowing it provides nothing much more than the tissue that allows you to do that heavy anaerobic work you seem to be doing all the time. That is why it is much easier to lose muscle than fat, and why people who think starving themselves will make them leaner and better looking are dead wrong, all their muscle will be gone before serious fat loss begins.

Now to try and answer your question. The idea behind losing just fat is to convince your body that the adipose tissue (had to throw in one fancy word to keep up) is no longer necessary. By maintaining a solid diet made up of useful foods your body will be in no rush to burn off muscle, because you are giving it the fuel to maintain it, and if you continue to lift the heaviest weights possible, your body will get the message that it cannot afford to shed the muscle because you will continue to do such grueling work. If however you are in a caloric deficit, and the signal is being sent that weight needs to be shed, your body will start to shed bodyfat, because if you are eating frequently enough and convincing your body that starvation will not be occuring anytime soon, it will slowly start burning off fat, for most people to the tune of one pound a week. It's as if it doesn't believe you, because only a hundred years ago or so there were no refridgerators and our ancestors will still hunting for meals and starving occasionally. Our genetics make it so that the body readily stores fat to prevent against death from starvation, because that function was crucial to survival throughout evolution and was right up until around the industrial revolution, in this country at least. In lots of third world countries that function is still crucial to survival. In most of America however, it's the reason most people are fat, and the people that aren't have very little muscle mass.


So I really think it just comes down to proving to your body that the muscle is not expendable because you will continue to lift heavy weights and it needs muscle to support this frequent activity, and that you will continue to fuel it to support muscle tissue. It also comes down to being in a caloric deficit, eating frequently enough to demonstrate to the body that it doesn't need to worry about starvation too much, so it will slowly diminish fat stores.

And that's why every sound cutting diet/fat loss program follows that protocol.

[InTeNsIFieR]

Stored fat is there incase your body needs to survive in starvation mode, and it is the body's last line of defense before the need to digest organs. Muscle however, is not the last line of defense, and if you were starving yourself your body would target the muscle first, knowing it provides nothing much more than the tissue that allows you to do that heavy anaerobic work you seem to be doing all the time. That is why it is much easier to lose muscle than fat, and why people who think starving themselves will make them leaner and better looking are dead wrong, all their muscle will be gone before serious fat loss begins.

I'm stranded on an island. I have no food but I have water and I'm as fat as a Fat Bastard from Austin Powers. Now, my starvation goes on for about 50 days. Surely this must set off fat loss, yes? But wait a minute, using your 'hypothesis' my body will utilize all my muscle protein for energy (that is excluding body organs). So on a 51st day I wake up (hypothetically), encountering a large tiger running towards me. What do I do? I try to generate mechanical energy due to a fight or flight response, in order to save my fat ass from the tiger. But wait a minute, I have no muscles to aid me, but I have large fat stores to....use......later? I do not believe it works that way. It's an extreme example too I'll admit. An organism is required to have muscles to carry out its normal function. Hence as a protection, body will limit muscle-protein degradation as the starvation goes on. Gluconeogenesis is indeed rapid at the start of starvation, which in turn causes you to utilize muscle-protein for production of glucose, along with fats, until sufficient amount of ketone bodies are produced to be used as a source of fuel. Mind you the protein is still being degraded just not as much. In which case lipolysis will always dominate over muscle-protein degradation.

On another note, if what you're saying is true, then why does 1 gram of fat yields more kilocalories than one gram of protein?

Muscle protein is not preferred source of fuel over adipose tissue.

[Gibblets]

dude, geez

i wasnt putting forth a scientific theory. i was trying to explain why i thought fat tissue is primarily shed over muscle tissue when following a proper cutting diet. i didnt say every single muscle fiber is consumed before fat is lost in a starvation diet. im sure some fat gets lost in the early stages, but losses in muscle size and strength would be more noticeable in a starvation diet than fat losses. Obviously your body would burn off the fat you had before targeting the muscle your body uses to move and function. What i was talking about was the excessive, and as far as the body is concerned unneccessary muscle that a person would have as a result of being either naturally muscle bound or bigger from lifting.

I didn't say muscle protein was a preferred source of fuel either, but starvation is a lot different than day to day dietary habits. If a person is well fed the body wont target muscle tissue or use protein for fuel, but if the body is starving, excess muscle tissue will be targeted before fat stores. Thats why you dont see any jacked anorexics or even remotely healthy looking ones.

[BigTruckGuy3500]

Gibblets put down good info. So did Intensifier. If you are as fat as fat bastard, chances are you body willl use a majority of fat first, then protein from muscles. If you're leaner, say around 15% body fat, your body senses a threat faster because body fat levels affect hormone levels. If you don't use it, you lose it. So if you're completely starving, as long as you're moving around you won't lose all your muscle. But there are those people who break something, are stuck in bed for a couple months, and come out extremely weak, even though they are being fed well. I think you both probably know what you're talking about, you just misunderstood each other.