Fat Burning Zone?
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qkrzazzang
Posts: 67 Member
I'm now 22 years old, 5'8 and 189lb. 23.4% body fat.
On Monday, Wednesday, Friday and Sunday, I do 100 squats (10 sets of 10) followed by 30 minutes brisk walk (4.0mph) and some jogs in between.
Tuesday, Thursday and Saturday I do benchpress/weightlift (30 each) and cycling HIIT (20sec on/ 2min off for 5-7 times) at the level of 8.
I recently encountered what is called a fat burning zone, putting the effort of 60-75% of a max heart rate that is. I'm seeing half the time that it's a myth, and I see other half the time that it is true that less intensity burns more fat and higher intensity burns less fat but more glycogen like carbs. I can't just rely on statements that say this is true/not true, but I want to hear experiences about the actual intensity put into cardio exercises from those who successfully lost big chunks of fat. As I said, my body is 23.4% body fat, so this is what I need to get rid of the most. I'm on a low carb diet, so I'm not too worried about carbs (not sure if this is even logical to say). I don't measure HR for HIIT because I myself know that I put in 100% effort anyways. For treadmill exercise, I get an average HR of about 165 in the span of 30 minutes. According to my max heart rate, which is 198, this is about 83% of my max heart rate, but I'm getting this much when I'm not even jogging, but brisk walking at a speed of 4mph. Does this seem accurate? This is a HR monitor built into the treadmill (though I think it's a pretty high tech, having a large screen which the internet, bluetooth and etc are all accessible). I feel so lost at this point
Much help appreciated.
On Monday, Wednesday, Friday and Sunday, I do 100 squats (10 sets of 10) followed by 30 minutes brisk walk (4.0mph) and some jogs in between.
Tuesday, Thursday and Saturday I do benchpress/weightlift (30 each) and cycling HIIT (20sec on/ 2min off for 5-7 times) at the level of 8.
I recently encountered what is called a fat burning zone, putting the effort of 60-75% of a max heart rate that is. I'm seeing half the time that it's a myth, and I see other half the time that it is true that less intensity burns more fat and higher intensity burns less fat but more glycogen like carbs. I can't just rely on statements that say this is true/not true, but I want to hear experiences about the actual intensity put into cardio exercises from those who successfully lost big chunks of fat. As I said, my body is 23.4% body fat, so this is what I need to get rid of the most. I'm on a low carb diet, so I'm not too worried about carbs (not sure if this is even logical to say). I don't measure HR for HIIT because I myself know that I put in 100% effort anyways. For treadmill exercise, I get an average HR of about 165 in the span of 30 minutes. According to my max heart rate, which is 198, this is about 83% of my max heart rate, but I'm getting this much when I'm not even jogging, but brisk walking at a speed of 4mph. Does this seem accurate? This is a HR monitor built into the treadmill (though I think it's a pretty high tech, having a large screen which the internet, bluetooth and etc are all accessible). I feel so lost at this point
Much help appreciated. 0
Replies
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You can lose "big chunks of fat" training in the fat burning zone.
Or training close to your sustainable peak, or with HIIT, or strolling gently or doing absolutely no exercise at all.....
Fat loss is down to calorie balance over time not what HR you train at. It's fat loss over the whole day that matters not the hour you train.
For fat loss whether you predominately use fat to fuel exercise (low intensities) or carbs/glycogen (higher intensities) makes little difference - with the caveat at lower intensity you can train longer and have a higher overall burn.
Training zones have relevance for training for sport however. If you are into endurance cardio (long distance cycling for example) then zone training makes sense.
PS
Your max HR isn't the simple 220 minus age formula. That's just a very, very rough approximation. Better off doing a max HR test if you are reasonably fit/healthy.
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I think the "fat burning zone" is marketing.
My reasoning: Working out at close your max HR is hard work.
Now, if you haven't exercised for a while, chances are you also have issues with needing to loose fat.
As someone new to exercise, working out as hard as possible is going to suck - big time.
Chances are, that person might not want to work out again after enduring an intensive workout.
However, if they workout at a less intense pace - they might "enjoy" it.
If they enjoy the exercise - they may repeat doing said exercise.
But some people have an idea that exercise isn't about enjoyment.
So, trainers (from Big Sport) came up with this "fat burning zone" to counter this absurd idea that doing moderate exercise is fun.
It's not fun - it's not pleasant - it's "fat burning" TM.
This is probably complete rubbish.
My motto:
Use a kitchen to lose weight.
Use exercise to make you feel better (at whatever rate you feel most comfortable doing).
And you can always check your own heart rate by counting the number of beats in 15 seconds, and then multiplying by 4.0 -
The fat burning zone is not marketing. Although I can see why it would be perceived as such. There is plenty of research showing the fat burning zone. I do agree that it is used to keep clients motivated when they do not want to exert 100% effort. Your schedule of using HIIT some days and walking others is good because it is giving you a balance between both. The fat burning zone is simply a time when your body uses lipids (fat) as energy as opposed to sugars (carbs). When you workout at higher intensity you will still burn fat you just burn carbs at the same time. The higher intensity will allow you to burn more total calories which is your goal.0
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I agree, at a lower intensity level, the body dose rely more on fat as a fuel source (as it has more time to breakdown fat and convert it to energy).
In contrast, during high intensity efforts, the body metabolizes carbohydrates instead, preferring their speed of breakdown to fuel higher levels of exertion. This fuel preference is also dictated by the availability of oxygen which is required for fat utilization.
That's just science.
But, the idea that there is a "zone" for fat loss, without any consideration of a calorie deficit (derived either by diet and/or exercise), is something that could plausibly be dreamed up in an office somewhere. You may burn a little more fat during exercise, but if a calorie deficit isn't present, then it will all even out in the end you won't lose much fat at all.
dwick1017 is right - you need a balance of high and low intensity, and to burn more total calories (whichever way best suits you).0 -
The fat burning zone is not marketing. Although I can see why it would be perceived as such. There is plenty of research showing the fat burning zone. I do agree that it is used to keep clients motivated when they do not want to exert 100% effort. Your schedule of using HIIT some days and walking others is good because it is giving you a balance between both. The fat burning zone is simply a time when your body uses lipids (fat) as energy as opposed to sugars (carbs). When you workout at higher intensity you will still burn fat you just burn carbs at the same time. The higher intensity will allow you to burn more total calories which is your goal.
What you fail to mention is that the "fat burning zone" is entirely meaningless in the context of weight loss.
OP unless you're training for endurance events forget you ever heard the term, if you're a triathlete or marathoner training your body to burn fat a fuel is useful (most people will only have 90 - 120 minutes of stored glycogen, even a skinny marathoner will have fat stores that can be used as fuel)
Having said that....working at lower intensities for longer periods of time also helps build endurance but doesn't speed up fat loss.
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While it exists, it's NOT the best way to burn fat. Calorie deficit is. And believe it or not, one could exercise 1 hour a low level, and still not burn as much fat if they had a good night's sleep. Because at rest, the body burns the most body fat percentage wise.
That's why exercise isn't even needed to do it. I would encourage exercise to improve fitness and health and to help create a calorie deficit though.
A.C.E. Certified Personal and Group Fitness Trainer
IDEA Fitness member
Kickboxing Certified Instructor
Been in fitness for 30 years and have studied kinesiology and nutrition
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Aside from the term, "fat burning zone", the other stat you quote, "putting the effort of 60-75% of a max heart rate " is actually more relevant. We call this effort "easy" in running speak. It's around the level we call "conversational". When you exercise at 60-70% max heart rate, you are pretty much relying on your aerobic capability. Any intensity harder than ~80% of your max heart rate would put you ahead of your aerobic threshold which as a result increases your lactate accumulation.
What this means that if you exercised right at your threshold, it would be comfortably hard, and you could only sustain this level for at most 50-60 minutes. Along with lactate accumulation is hydrogen ions which makes your muscles and blood acidity. They makes the nerves in your muscles irritated and messages to your brain that tell you to stop.
So to make a long story short, staying within your aerobic zone means you can go a lot longer and further especially if you plan to exercise for longer than 90 minutes (you can burn more calories over time). Also, when you begin to go beyond your aerobic threshold, the body can only burn glycogen. Fat cannot be burned in the anaerobic zone.
However, you will also not burn any fat until your stored carb (glycogen) is in a pretty good depletion state. Your body prefers glycogen to fuel excercise because it is a much simplier process to burn carbs than it is to burn fatty acids. So in order to burn fat, you have to first deplete some of your glycogen anyway.
Different ways to deplete your glycogen in order to burn fat:
1) exercise fasted first thing in the morning
(you deplete lots of glycogen while you sleep for 8 hours) You also begin to burn lots of fat too while sleeping.
2) Exercise at your theshold for 30 minutes, then slow down the intensity for a fat burning workout.
3) Exercise at your comfortable easy (60-70% mhr) intensity for longer than 90 minutes.
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A lot of well reasoned responses here in my opinion, which can be rare sometimes on the forums.
Without much else to add, I think a lot of the "myth" of the fat burning or weight loss zone would exist (or not) depending on how it was defined by any particular person/group/entity.
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Aside from the term, "fat burning zone", the other stat you quote, "putting the effort of 60-75% of a max heart rate " is actually more relevant. We call this effort "easy" in running speak. It's around the level we call "conversational". When you exercise at 60-70% max heart rate, you are pretty much relying on your aerobic capability. Any intensity harder than ~80% of your max heart rate would put you ahead of your aerobic threshold which as a result increases your lactate accumulation.
What this means that if you exercised right at your threshold, it would be comfortably hard, and you could only sustain this level for at most 50-60 minutes. Along with lactate accumulation is hydrogen ions which makes your muscles and blood acidity. They makes the nerves in your muscles irritated and messages to your brain that tell you to stop.
So to make a long story short, staying within your aerobic zone means you can go a lot longer and further especially if you plan to exercise for longer than 90 minutes (you can burn more calories over time). Also, when you begin to go beyond your aerobic threshold, the body can only burn glycogen. Fat cannot be burned in the anaerobic zone.
However, you will also not burn any fat until your stored carb (glycogen) is in a pretty good depletion state. Your body prefers glycogen to fuel excercise because it is a much simplier process to burn carbs than it is to burn fatty acids. So in order to burn fat, you have to first deplete some of your glycogen anyway.
Different ways to deplete your glycogen in order to burn fat:
1) exercise fasted first thing in the morning
(you deplete lots of glycogen while you sleep for 8 hours) You also begin to burn lots of fat too while sleeping.
2) Exercise at your theshold for 30 minutes, then slow down the intensity for a fat burning workout.
3) Exercise at your comfortable easy (60-70% mhr) intensity for longer than 90 minutes.
Currently, I am on a low carb diet, so perhaps I could care less about depletion of carb (maybe?). But I did eat lots of high carb foods like breads before I started to get into a strict diet. Now my food is almost entirely based on chicken breast, eggs and vegetables. In my case, would I still need to consider carb burning prior to fat burning? I don't necessarily know how the idea of carb storage works.
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Glycogen is also formed from proteins, so essentially any diet and any body will store it. It's simply the easiest and quickest method for the body to store quick reserves of glucose. Think of it as a similar function to fat storage and use, it's just an easier and quicker form for the body to convert, and is also limited in the amount that can be stored.0
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However, you will also not burn any fat until your stored carb (glycogen) is in a pretty good depletion state. Your body prefers glycogen to fuel excercise because it is a much simplier process to burn carbs than it is to burn fatty acids. So in order to burn fat, you have to first deplete some of your glycogen anyway.
The type of fuel burned during exercise is irrelevant from a fat-loss perspective. Losing body fat only requires a sustained calorie deficit, not low-carb, and not even exercise.
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@Stoshew71However, you will also not burn any fat until your stored carb (glycogen) is in a pretty good depletion state. Your body prefers glycogen to fuel excercise because it is a much simplier process to burn carbs than it is to burn fatty acids. So in order to burn fat, you have to first deplete some of your glycogen anyway.
Sorry but that is incorrect. You burn a blend of fuel depending on the exercise intensity - it's not glycogen/carbs and then fat, it's a sliding scale from all fat, to a blend of both, to all carbs, to anaerobic.
Respiratory exchange ratio.
The respiratory exchange ratio (RER) is the ratio of carbon dioxide produced from the quantity of oxygen inhaled. This ratio can be used to estimate the source of fuel or mixture of fuels the individual is relying on. Values range from 0.7, indicating total reliance on fats as a fuel source, 0.85 being a mixture of fats and carbohydrates, 1.00 being total dependence on carbohydrate and anything above 1.00 indicating the
individual is now relying on anaerobic sources to meet their energy demands.
Putting my results from an old VO2 max test into that framework I'm burning fat/carb mix from 90bpm to 120bpm (c. 60 to 120 watts power output)
Around 150bpm I'm almost entirely carb fuelled (180 watts).
Between 155bpm and my max HR I'm switching to anaerobic (180 - 210 watts).
Pet peeve!
WIsh people would focus on exercise performance and not the type of fuel used during exercise which is pretty much irrelevant for weight loss/fat loss.0 -
@Stoshew71However, you will also not burn any fat until your stored carb (glycogen) is in a pretty good depletion state. Your body prefers glycogen to fuel excercise because it is a much simplier process to burn carbs than it is to burn fatty acids. So in order to burn fat, you have to first deplete some of your glycogen anyway.
Sorry but that is incorrect. You burn a blend of fuel depending on the exercise intensity - it's not glycogen/carbs and then fat, it's a sliding scale from all fat, to a blend of both, to all carbs, to anaerobic.
Respiratory exchange ratio.
The respiratory exchange ratio (RER) is the ratio of carbon dioxide produced from the quantity of oxygen inhaled. This ratio can be used to estimate the source of fuel or mixture of fuels the individual is relying on. Values range from 0.7, indicating total reliance on fats as a fuel source, 0.85 being a mixture of fats and carbohydrates, 1.00 being total dependence on carbohydrate and anything above 1.00 indicating the
individual is now relying on anaerobic sources to meet their energy demands.
Putting my results from an old VO2 max test into that framework I'm burning fat/carb mix from 90bpm to 120bpm (c. 60 to 120 watts power output)
Around 150bpm I'm almost entirely carb fuelled (180 watts).
Between 155bpm and my max HR I'm switching to anaerobic (180 - 210 watts).
Pet peeve!
WIsh people would focus on exercise performance and not the type of fuel used during exercise which is pretty much irrelevant for weight loss/fat loss.
Good info. But I'm curious, did your VO2 max testing not start low enough to where you were reliant only on fat? Understanding fully that 90 bpm is a fairly low starting point, just a curiosity question.
As for your pet peeve comment, I think that sometimes people get caught up in thinking "if I burn fat while in deficit it stays gone". From my understanding regardless of the fuel source (carb or fat) the carb/glycogen reserves will replenish to roughly the same amounts (barring major changes that allow better muscle/cell/organ retention), and the fat will replenish more based on total deficit.
So in the end, it really still comes down to deficit and the total calorie burn of any single workout might only affect what reserves the body must replenish.0 -
robertw486 wrote: »
@Stoshew71However, you will also not burn any fat until your stored carb (glycogen) is in a pretty good depletion state. Your body prefers glycogen to fuel excercise because it is a much simplier process to burn carbs than it is to burn fatty acids. So in order to burn fat, you have to first deplete some of your glycogen anyway.
Sorry but that is incorrect. You burn a blend of fuel depending on the exercise intensity - it's not glycogen/carbs and then fat, it's a sliding scale from all fat, to a blend of both, to all carbs, to anaerobic.
Respiratory exchange ratio.
The respiratory exchange ratio (RER) is the ratio of carbon dioxide produced from the quantity of oxygen inhaled. This ratio can be used to estimate the source of fuel or mixture of fuels the individual is relying on. Values range from 0.7, indicating total reliance on fats as a fuel source, 0.85 being a mixture of fats and carbohydrates, 1.00 being total dependence on carbohydrate and anything above 1.00 indicating the
individual is now relying on anaerobic sources to meet their energy demands.
Putting my results from an old VO2 max test into that framework I'm burning fat/carb mix from 90bpm to 120bpm (c. 60 to 120 watts power output)
Around 150bpm I'm almost entirely carb fuelled (180 watts).
Between 155bpm and my max HR I'm switching to anaerobic (180 - 210 watts).
Pet peeve!
WIsh people would focus on exercise performance and not the type of fuel used during exercise which is pretty much irrelevant for weight loss/fat loss.
Good info. But I'm curious, did your VO2 max testing not start low enough to where you were reliant only on fat? Understanding fully that 90 bpm is a fairly low starting point, just a curiosity question.
As for your pet peeve comment, I think that sometimes people get caught up in thinking "if I burn fat while in deficit it stays gone". From my understanding regardless of the fuel source (carb or fat) the carb/glycogen reserves will replenish to roughly the same amounts (barring major changes that allow better muscle/cell/organ retention), and the fat will replenish more based on total deficit.
So in the end, it really still comes down to deficit and the total calorie burn of any single workout might only affect what reserves the body must replenish.
@robertw486
They try and judge the VO2 max test start point to get you to "failure" in a reasonable length of time so can't start at too low an effort. I believe that should be within fifteen minutes ideally. Did mine on a bike and resistance is steadily added strictly every 2:30 minutes so you go up in a series of ramps. They actually started me at too low a point (because I'm old perhaps???) and it took 23 minutes to get to maximal effort so my score was probably a bit lower due to fatigue.0 -
robertw486 wrote: »Glycogen is also formed from proteins, so essentially any diet and any body will store it. It's simply the easiest and quickest method for the body to store quick reserves of glucose. Think of it as a similar function to fat storage and use, it's just an easier and quicker form for the body to convert, and is also limited in the amount that can be stored.
True: process known as gluconeogenesis. Not an expert on low carb or keto, so I am not sure how the ratios work out, but the idea behind low carb is that you deplete your glycogen stores over a period of a few days in order to force your body to work more off of fat then carbs. You go through a period known as Adkins flu where you feel very weak as you undergo the process of changing over from carbs to fat. Again not that i am an expert or actually gone through it before personally, but just from reading about low carb diets and effects.Cherimoose wrote: »However, you will also not burn any fat until your stored carb (glycogen) is in a pretty good depletion state. Your body prefers glycogen to fuel excercise because it is a much simplier process to burn carbs than it is to burn fatty acids. So in order to burn fat, you have to first deplete some of your glycogen anyway.
The type of fuel burned during exercise is irrelevant from a fat-loss perspective. Losing body fat only requires a sustained calorie deficit, not low-carb, and not even exercise.
The OP specifically was asking about fat burning zone (I am assuming from treadmill workout), so I answered from that prospective. However, I agree that diet works more for overall fat loss and working out is just a factor that plays into that.
@Stoshew71However, you will also not burn any fat until your stored carb (glycogen) is in a pretty good depletion state. Your body prefers glycogen to fuel excercise because it is a much simplier process to burn carbs than it is to burn fatty acids. So in order to burn fat, you have to first deplete some of your glycogen anyway.
Sorry but that is incorrect. You burn a blend of fuel depending on the exercise intensity - it's not glycogen/carbs and then fat, it's a sliding scale from all fat, to a blend of both, to all carbs, to anaerobic.
Respiratory exchange ratio.
The respiratory exchange ratio (RER) is the ratio of carbon dioxide produced from the quantity of oxygen inhaled. This ratio can be used to estimate the source of fuel or mixture of fuels the individual is relying on. Values range from 0.7, indicating total reliance on fats as a fuel source, 0.85 being a mixture of fats and carbohydrates, 1.00 being total dependence on carbohydrate and anything above 1.00 indicating the
individual is now relying on anaerobic sources to meet their energy demands.
Putting my results from an old VO2 max test into that framework I'm burning fat/carb mix from 90bpm to 120bpm (c. 60 to 120 watts power output)
Around 150bpm I'm almost entirely carb fuelled (180 watts).
Between 155bpm and my max HR I'm switching to anaerobic (180 - 210 watts).
Pet peeve!
WIsh people would focus on exercise performance and not the type of fuel used during exercise which is pretty much irrelevant for weight loss/fat loss.
I think we will both agree that for the first few moments you get on the treadmill and start running, you will more likely be burning more stored carbs than stored fat. But over time, you will be switching over to more fat and less carbs (as long as intensity is kept low enough). How long it takes, depends on intensity (as you suggested) and how well trained the runner is. If you are running at too hard of an intensity then you will be doing 1 of 2 things: forcing your body to continue burning carbs because the hard intensity requires glycolysis to be used (because you backed up the Krebs and ETC due to overprocessing oxygen beyond your capability) and only glucose from carbs can be used at this point, or eventually you continue this to the point where lactic and H-ions accumulate too much and you no longer can continue the exercise.
Your RER explanation is confusing. CO2 exhaled is a result of completing the aerobic (Krebs Cycle and ETC) process. In normal carb burning, you will first use glycolysis to make pyruvate and a small amount of ATP. if enough oxygen is available in the mitochondria then that pyruvate can be used to burn it all the way aerobically with water and CO2 as byproducts. Otherwise the the pyruvate undergoes fermintation with lactate and H-ions as byproducts. But fatty acids oxydation and in rarer cases amino acid catabolism can also be used in the aerobic process which would also result in exhaling of CO2. The amount of oxygen you breath in verses CO2 being breathed out shouldn't be a ratio what type of fuel used, but whether or not the Krebs and ETC was used to metabolized fuel which can be carbs, fats, and in rarer cases proteins. The ability to use Krebs and ETC is a matter of consistent aerobic base building. I would just think that measuring what ratios of different fuels is being used would be more complicated than just comparing how much O2 being breathed in verses CO2 being breathed out.
The bpm increase in your running would suggest a faster pace if stride length stayed the same.
However this is not always the case and in more experienced runners, they maintain stride rate (spm) no matter what the pace or intensity they are running at. Me, for example, I right now have a pretty consistent stride rate of 170 spm and working towards 180 spm.
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robertw486 wrote: »Glycogen is also formed from proteins, so essentially any diet and any body will store it. It's simply the easiest and quickest method for the body to store quick reserves of glucose. Think of it as a similar function to fat storage and use, it's just an easier and quicker form for the body to convert, and is also limited in the amount that can be stored.
True: process known as gluconeogenesis. Not an expert on low carb or keto, so I am not sure how the ratios work out, but the idea behind low carb is that you deplete your glycogen stores over a period of a few days in order to force your body to work more off of fat then carbs. You go through a period known as Adkins flu where you feel very weak as you undergo the process of changing over from carbs to fat. Again not that i am an expert or actually gone through it before personally, but just from reading about low carb diets and effects.Cherimoose wrote: »However, you will also not burn any fat until your stored carb (glycogen) is in a pretty good depletion state. Your body prefers glycogen to fuel excercise because it is a much simplier process to burn carbs than it is to burn fatty acids. So in order to burn fat, you have to first deplete some of your glycogen anyway.
The type of fuel burned during exercise is irrelevant from a fat-loss perspective. Losing body fat only requires a sustained calorie deficit, not low-carb, and not even exercise.
The OP specifically was asking about fat burning zone (I am assuming from treadmill workout), so I answered from that prospective. However, I agree that diet works more for overall fat loss and working out is just a factor that plays into that.
@Stoshew71However, you will also not burn any fat until your stored carb (glycogen) is in a pretty good depletion state. Your body prefers glycogen to fuel excercise because it is a much simplier process to burn carbs than it is to burn fatty acids. So in order to burn fat, you have to first deplete some of your glycogen anyway.
Sorry but that is incorrect. You burn a blend of fuel depending on the exercise intensity - it's not glycogen/carbs and then fat, it's a sliding scale from all fat, to a blend of both, to all carbs, to anaerobic.
Respiratory exchange ratio.
The respiratory exchange ratio (RER) is the ratio of carbon dioxide produced from the quantity of oxygen inhaled. This ratio can be used to estimate the source of fuel or mixture of fuels the individual is relying on. Values range from 0.7, indicating total reliance on fats as a fuel source, 0.85 being a mixture of fats and carbohydrates, 1.00 being total dependence on carbohydrate and anything above 1.00 indicating the
individual is now relying on anaerobic sources to meet their energy demands.
Putting my results from an old VO2 max test into that framework I'm burning fat/carb mix from 90bpm to 120bpm (c. 60 to 120 watts power output)
Around 150bpm I'm almost entirely carb fuelled (180 watts).
Between 155bpm and my max HR I'm switching to anaerobic (180 - 210 watts).
Pet peeve!
WIsh people would focus on exercise performance and not the type of fuel used during exercise which is pretty much irrelevant for weight loss/fat loss.
I think we will both agree that for the first few moments you get on the treadmill and start running, you will more likely be burning more stored carbs than stored fat. But over time, you will be switching over to more fat and less carbs (as long as intensity is kept low enough). How long it takes, depends on intensity (as you suggested) and how well trained the runner is. If you are running at too hard of an intensity then you will be doing 1 of 2 things: forcing your body to continue burning carbs because the hard intensity requires glycolysis to be used (because you backed up the Krebs and ETC due to overprocessing oxygen beyond your capability) and only glucose from carbs can be used at this point, or eventually you continue this to the point where lactic and H-ions accumulate too much and you no longer can continue the exercise.
Your RER explanation is confusing. CO2 exhaled is a result of completing the aerobic (Krebs Cycle and ETC) process. In normal carb burning, you will first use glycolysis to make pyruvate and a small amount of ATP. if enough oxygen is available in the mitochondria then that pyruvate can be used to burn it all the way aerobically with water and CO2 as byproducts. Otherwise the the pyruvate undergoes fermintation with lactate and H-ions as byproducts. But fatty acids oxydation and in rarer cases amino acid catabolism can also be used in the aerobic process which would also result in exhaling of CO2. The amount of oxygen you breath in verses CO2 being breathed out shouldn't be a ratio what type of fuel used, but whether or not the Krebs and ETC was used to metabolized fuel which can be carbs, fats, and in rarer cases proteins. The ability to use Krebs and ETC is a matter of consistent aerobic base building. I would just think that measuring what ratios of different fuels is being used would be more complicated than just comparing how much O2 being breathed in verses CO2 being breathed out.
The bpm increase in your running would suggest a faster pace if stride length stayed the same.
However this is not always the case and in more experienced runners, they maintain stride rate (spm) no matter what the pace or intensity they are running at. Me, for example, I right now have a pretty consistent stride rate of 170 spm and working towards 180 spm.
Not sure if I am misreading your comments, but RQ/RER are well-established measurements that are used to determine the ratio of carbs/fats used during exercise.
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robertw486 wrote: »
@Stoshew71However, you will also not burn any fat until your stored carb (glycogen) is in a pretty good depletion state. Your body prefers glycogen to fuel excercise because it is a much simplier process to burn carbs than it is to burn fatty acids. So in order to burn fat, you have to first deplete some of your glycogen anyway.
Sorry but that is incorrect. You burn a blend of fuel depending on the exercise intensity - it's not glycogen/carbs and then fat, it's a sliding scale from all fat, to a blend of both, to all carbs, to anaerobic.
Respiratory exchange ratio.
The respiratory exchange ratio (RER) is the ratio of carbon dioxide produced from the quantity of oxygen inhaled. This ratio can be used to estimate the source of fuel or mixture of fuels the individual is relying on. Values range from 0.7, indicating total reliance on fats as a fuel source, 0.85 being a mixture of fats and carbohydrates, 1.00 being total dependence on carbohydrate and anything above 1.00 indicating the
individual is now relying on anaerobic sources to meet their energy demands.
Putting my results from an old VO2 max test into that framework I'm burning fat/carb mix from 90bpm to 120bpm (c. 60 to 120 watts power output)
Around 150bpm I'm almost entirely carb fuelled (180 watts).
Between 155bpm and my max HR I'm switching to anaerobic (180 - 210 watts).
Pet peeve!
WIsh people would focus on exercise performance and not the type of fuel used during exercise which is pretty much irrelevant for weight loss/fat loss.
Good info. But I'm curious, did your VO2 max testing not start low enough to where you were reliant only on fat? Understanding fully that 90 bpm is a fairly low starting point, just a curiosity question.
As for your pet peeve comment, I think that sometimes people get caught up in thinking "if I burn fat while in deficit it stays gone". From my understanding regardless of the fuel source (carb or fat) the carb/glycogen reserves will replenish to roughly the same amounts (barring major changes that allow better muscle/cell/organ retention), and the fat will replenish more based on total deficit.
So in the end, it really still comes down to deficit and the total calorie burn of any single workout might only affect what reserves the body must replenish.
One is never "entirely reliant on fat". One probably burns the highest percentage of fat for fuel when sleeping.
The ratio of carbs:fats used during exercise is affected, among other things, by training. Someone who does primarily tempo, threshold, or high-intensity exercise, might find that they go primarily to carbs at a fairly low % of VO2 max.
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robertw486 wrote: »
@Stoshew71However, you will also not burn any fat until your stored carb (glycogen) is in a pretty good depletion state. Your body prefers glycogen to fuel excercise because it is a much simplier process to burn carbs than it is to burn fatty acids. So in order to burn fat, you have to first deplete some of your glycogen anyway.
Sorry but that is incorrect. You burn a blend of fuel depending on the exercise intensity - it's not glycogen/carbs and then fat, it's a sliding scale from all fat, to a blend of both, to all carbs, to anaerobic.
Respiratory exchange ratio.
The respiratory exchange ratio (RER) is the ratio of carbon dioxide produced from the quantity of oxygen inhaled. This ratio can be used to estimate the source of fuel or mixture of fuels the individual is relying on. Values range from 0.7, indicating total reliance on fats as a fuel source, 0.85 being a mixture of fats and carbohydrates, 1.00 being total dependence on carbohydrate and anything above 1.00 indicating the
individual is now relying on anaerobic sources to meet their energy demands.
Putting my results from an old VO2 max test into that framework I'm burning fat/carb mix from 90bpm to 120bpm (c. 60 to 120 watts power output)
Around 150bpm I'm almost entirely carb fuelled (180 watts).
Between 155bpm and my max HR I'm switching to anaerobic (180 - 210 watts).
Pet peeve!
WIsh people would focus on exercise performance and not the type of fuel used during exercise which is pretty much irrelevant for weight loss/fat loss.
Good info. But I'm curious, did your VO2 max testing not start low enough to where you were reliant only on fat? Understanding fully that 90 bpm is a fairly low starting point, just a curiosity question.
As for your pet peeve comment, I think that sometimes people get caught up in thinking "if I burn fat while in deficit it stays gone". From my understanding regardless of the fuel source (carb or fat) the carb/glycogen reserves will replenish to roughly the same amounts (barring major changes that allow better muscle/cell/organ retention), and the fat will replenish more based on total deficit.
So in the end, it really still comes down to deficit and the total calorie burn of any single workout might only affect what reserves the body must replenish.
@robertw486
They try and judge the VO2 max test start point to get you to "failure" in a reasonable length of time so can't start at too low an effort. I believe that should be within fifteen minutes ideally. Did mine on a bike and resistance is steadily added strictly every 2:30 minutes so you go up in a series of ramps. They actually started me at too low a point (because I'm old perhaps???) and it took 23 minutes to get to maximal effort so my score was probably a bit lower due to fatigue.
Thanks for the quick response. That answers another question I had, which was the wattage numbers and type of test. For some reason I was under the impression that most VO2 max testing ramped up quicker, so was expecting higher wattage numbers.
As for the start point thing, I've been there getting some heart testing done. I had to have my heart rate at IIRC 135 plus, and told the doctor when they started the treadmill that unless the thing went a lot quicker it wasn't going to happen. He was sure it would. After I maxed the treadmill they had to hit me with the IV stuff that raised my heart rate.0 -
robertw486 wrote: »Glycogen is also formed from proteins, so essentially any diet and any body will store it. It's simply the easiest and quickest method for the body to store quick reserves of glucose. Think of it as a similar function to fat storage and use, it's just an easier and quicker form for the body to convert, and is also limited in the amount that can be stored.
True: process known as gluconeogenesis. Not an expert on low carb or keto, so I am not sure how the ratios work out, but the idea behind low carb is that you deplete your glycogen stores over a period of a few days in order to force your body to work more off of fat then carbs. You go through a period known as Adkins flu where you feel very weak as you undergo the process of changing over from carbs to fat. Again not that i am an expert or actually gone through it before personally, but just from reading about low carb diets and effects.Cherimoose wrote: »However, you will also not burn any fat until your stored carb (glycogen) is in a pretty good depletion state. Your body prefers glycogen to fuel excercise because it is a much simplier process to burn carbs than it is to burn fatty acids. So in order to burn fat, you have to first deplete some of your glycogen anyway.
The type of fuel burned during exercise is irrelevant from a fat-loss perspective. Losing body fat only requires a sustained calorie deficit, not low-carb, and not even exercise.
The OP specifically was asking about fat burning zone (I am assuming from treadmill workout), so I answered from that prospective. However, I agree that diet works more for overall fat loss and working out is just a factor that plays into that.
@Stoshew71However, you will also not burn any fat until your stored carb (glycogen) is in a pretty good depletion state. Your body prefers glycogen to fuel excercise because it is a much simplier process to burn carbs than it is to burn fatty acids. So in order to burn fat, you have to first deplete some of your glycogen anyway.
Sorry but that is incorrect. You burn a blend of fuel depending on the exercise intensity - it's not glycogen/carbs and then fat, it's a sliding scale from all fat, to a blend of both, to all carbs, to anaerobic.
Respiratory exchange ratio.
The respiratory exchange ratio (RER) is the ratio of carbon dioxide produced from the quantity of oxygen inhaled. This ratio can be used to estimate the source of fuel or mixture of fuels the individual is relying on. Values range from 0.7, indicating total reliance on fats as a fuel source, 0.85 being a mixture of fats and carbohydrates, 1.00 being total dependence on carbohydrate and anything above 1.00 indicating the
individual is now relying on anaerobic sources to meet their energy demands.
Putting my results from an old VO2 max test into that framework I'm burning fat/carb mix from 90bpm to 120bpm (c. 60 to 120 watts power output)
Around 150bpm I'm almost entirely carb fuelled (180 watts).
Between 155bpm and my max HR I'm switching to anaerobic (180 - 210 watts).
Pet peeve!
WIsh people would focus on exercise performance and not the type of fuel used during exercise which is pretty much irrelevant for weight loss/fat loss.
I think we will both agree that for the first few moments you get on the treadmill and start running, you will more likely be burning more stored carbs than stored fat. But over time, you will be switching over to more fat and less carbs (as long as intensity is kept low enough). How long it takes, depends on intensity (as you suggested) and how well trained the runner is. If you are running at too hard of an intensity then you will be doing 1 of 2 things: forcing your body to continue burning carbs because the hard intensity requires glycolysis to be used (because you backed up the Krebs and ETC due to overprocessing oxygen beyond your capability) and only glucose from carbs can be used at this point, or eventually you continue this to the point where lactic and H-ions accumulate too much and you no longer can continue the exercise.
Your RER explanation is confusing. CO2 exhaled is a result of completing the aerobic (Krebs Cycle and ETC) process. In normal carb burning, you will first use glycolysis to make pyruvate and a small amount of ATP. if enough oxygen is available in the mitochondria then that pyruvate can be used to burn it all the way aerobically with water and CO2 as byproducts. Otherwise the the pyruvate undergoes fermintation with lactate and H-ions as byproducts. But fatty acids oxydation and in rarer cases amino acid catabolism can also be used in the aerobic process which would also result in exhaling of CO2. The amount of oxygen you breath in verses CO2 being breathed out shouldn't be a ratio what type of fuel used, but whether or not the Krebs and ETC was used to metabolized fuel which can be carbs, fats, and in rarer cases proteins. The ability to use Krebs and ETC is a matter of consistent aerobic base building. I would just think that measuring what ratios of different fuels is being used would be more complicated than just comparing how much O2 being breathed in verses CO2 being breathed out.
The bpm increase in your running would suggest a faster pace if stride length stayed the same.
However this is not always the case and in more experienced runners, they maintain stride rate (spm) no matter what the pace or intensity they are running at. Me, for example, I right now have a pretty consistent stride rate of 170 spm and working towards 180 spm.
Not sure if I am misreading your comments, but RQ/RER are well-established measurements that are used to determine the ratio of carbs/fats used during exercise.
Not saying they are wrong, just don't quite understand how they work. Maybe I have to do more research on knowing the science behind it.
Edited after reading just a little bit on this.
Not that wikipedia is the most reliable source and I still have more reading to do, but here are some things that I was concerned about it when I first read your post on this.
Measuring this ratio can be used for estimating the respiratory quotient (RQ), an indicator of which fuel (carbohydrate or fat) is being metabolized to supply the body with energy. This estimation is only valid if metabolism is in a steady state.
During moderate or higher intensity aerobic exercise and anaerobic exercise, using RER for estimating RQ loses accuracy because of factors including bicarbonate buffering of hydrogen ions, which affects the CO2 levels being expelled by the respiratory system.
Anyway, not trying to stir an argument up. It's just the first time I heard this and am very curious on how this all works and why it works, and what limitations are there.0 -
Putting my results from an old VO2 max test into that framework I'm burning fat/carb mix from 90bpm to 120bpm (c. 60 to 120 watts power output)
Around 150bpm I'm almost entirely carb fuelled (180 watts).
Between 155bpm and my max HR I'm switching to anaerobic (180 - 210 watts).The bpm increase in your running would suggest a faster pace if stride length stayed the same.
However this is not always the case and in more experienced runners, they maintain stride rate (spm) no matter what the pace or intensity they are running at. Me, for example, I right now have a pretty consistent stride rate of 170 spm and working towards 180 spm.
This one I have to apologize on. My mind was defenitely somewhere else yesterday. We both were talking 2 different animals. You were refering to heart rate in beats per minute and I was for some reason thinking pace you were running.
I was involved in a completely different discussion talking about using music at certain rythms to help us run at a certain cadence. Part of that other discussion went into faster music made people run faster. Ideally, elite runners run at a cadence of 180 strides per second or more. Most recerational runners run at 160-165 spm. You can use music at certain beats per minute to help you speed up your cadence. My mistake on this one.
As far as heart rate, usually I just speak in terms of max HR since everyone's HRmax is different. What your HR of 150 bpm means something completely different to someone else who is in a different fitness level and VDOT measurement.
For example, I use 60-65% of MaxHR to say easy conversational effort.
80-85% MaxHR would suggest threshold running where you are near your lactate threshold.
90% and more and you are pretty much running anaerobically.
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