Burning Fat Calories
- Thread starter azspud
- Start date
azspud said:
while riding at a lower intensity (compared to a higher intensity) will promote greater fat oxidation, the actual amount of energy used will be less than if you exercised at a higher intensity.
To lose weight (fat) all that matters is that you expend more energy than you consume -- it doesn't matter what the 'fuel' mix is.
If you are therefore try to maximise fat loss, you should aim to exercise at the highest intensity that you can for the duration of the time you have available and that, that allows recovery for the next consecutive training session.
ric
I certainly agree with this.ric_stern/RST said:
I don't quite agree on this, but it might be because of limited knowledge.ric_stern/RST said:
I would argue that medium intensity training (zone 1-3) is better for weight loss.
Lets say I do an hour on the bike in zone 2 and expend a total of 600 calories, 300 calories from fat and 300 calories from glycogen. After the exercise I do not have to replace the fat I have burned, but I do, at some point have to replace the 300 calories of glycogen in order to recover properly. Net result: I have lost 300calories worth of fat, but I need to eat 300calories of carbo to restock my limited glycogen stores.
Now if I did an hour in the bike in zone 4, maybe I would expend 800 calories, but all of those calories would be from glygocen (assumption picked up from one of your earlier posts Ric). In order to restock and recover properly I would have to replace all of that glycogen with 800 calories of carbo. Net result: I have not lost any calories from fat, only from glycogen which is a scarce resource and has to be filled up by eating those extra 800cal at some point in time (unless I'm willing to sacrifice my recovery and feel like sh.. during my next ride...
)
azspud said:
I went from 205 lbs to 145 lbs by biking in the 80% to 87% Max Heart Rate zones. Did 2080 miles last year and this year did 1590.4 miles. Went from 193 to 159 last year and 162 to 145 this year.
Being in the 140's has made me a fast biker compared to when I started. Last year I would cruise at 18mph at 87% MHR. This year I can do 23 mph at 87% MHR.
You can still burn a lot of fat on an 87% MHR workout, but you have to bike at least 32 miles. My workouts are 35 to 56 miles long.
Aaberg said:
I'm certainly no expert but from what I've read: As intensity increases, the Fat to Glycogen fuel burn ratio decreases, yes, but not as fast as the total energy burn increases, with the result that at higher intensity MORE fat is burned than at any lower intensity (along with a LOT more glycogen), regardless of HR zone. Your point about recovery is a good one though. No point in burning more fat today if your too broken down to ride tomorrow
. When I'm trying to drop weight, which I am right now, I try to ride pretty hard most of the time because I don't have the hours available to build a negative balance at lower intensity since I can't diet for beans.
Just one opinion
azspud said:
Well, I keep meticulous records of my performance, mileage, and workouts to see if I'm improving from biking. I bike to lose weight but not enough to be a Cat 5 racer. To race I think I should do at least 160 miles a week.
Looking at my 2005 workout data shows that I lost the most weight from a workout when the workout averaged 79% MHR.
Check out my chart.
This thread has made me start to think more about properly using my HRM. I did some calculations and figured out that I pretty much have been riding in a range from 72-79% of my MHR. I use a Timex HRM that indicates the following zone information (based on a MHR).JTE83 said:
ZONE Lower Limit Upper Limit
5 ❘ 90% MHR ❘ 100% MHR
4 ❘ 80% ❘ 90%
3 ❘ 70% ❘ 80%
2 ❘ 60% ❘ 70%
1 ❘ 50% ❘ 60%
My question is am I understanding it correctly that if I continue to train in the Timex "Zone 4" that this actually corresponds to a real Zone 3? Also, the Timex indicates that the Total Calories Burned are calculated from elapsed time, heart rate data and body weight. This just gives me an approximate amount of calories burned but does not compute which are from Fat and which are from Glycogen.
Other information available while in review mode:
• In Zone - The amount of time your heart rate was within the target
zone you specified.
• Average Heart Rate
• Peak Heart Rate
• Total Calories Burned
Is there a way of calculate which calories burned are from Fat and which are from Glycogen based on the information that I have available?
Those two paragraphs are inaccurate, but I see what you're thinking. There is an intensity when you will burn approximately 50% fat and 50% carbohydrate (approximately being the key word there), but maintaining that for an entire ride isn't the easiest thing. You'll end up using more of one or the other as you go on in the ride and begin to become depleted of your blood glucose and/or muscle and liver glycogen stores. When you do burn those 600 calories after the ride, you didn't necessarily burn 300 from carbs and 300 from fat because during the ride, when it's over, during your recovery period, and at rest, there are all sorts of biochemical changes going on in your body where it's attempting to interconvert carbohydrate, protein, and fat appropriately to not only allow you to recover from the workout, but to also provide all of the other tissues and processes of the body with the appropriate amounts and types of energy.Aaberg said:I would argue that medium intensity training (zone 1-3) is better for weight loss.
Lets say I do an hour on the bike in zone 2 and expend a total of 600 calories, 300 calories from fat and 300 calories from glycogen. After the exercise I do not have to replace the fat I have burned, but I do, at some point have to replace the 300 calories of glycogen in order to recover properly. Net result: I have lost 300calories worth of fat, but I need to eat 300calories of carbo to restock my limited glycogen stores.
Now if I did an hour in the bike in zone 4, maybe I would expend 800 calories, but all of those calories would be from glygocen (assumption picked up from one of your earlier posts Ric). In order to restock and recover properly I would have to replace all of that glycogen with 800 calories of carbo. Net result: I have not lost any calories from fat, only from glycogen which is a scarce resource and has to be filled up by eating those extra 800cal at some point in time (unless I'm willing to sacrifice my recovery and feel like sh.. during my next ride...
But you will absolutely positively never ever in a million years have ALL of your calories come from glycogen. Think about the time spent warming up and getting up to that glycogen-burning zone (speaking hypothetically)...that time spent in lower intensities would burn at least 1 calorie from fat, so that negates any way of you burning all glycogen.
This fuel usage during exercise is actually a continuum. I can't seem to find the picture/graph that shows exactly what we're discussing, but will post it if I find it. Just know that there is always some ratio of fat to carbohydrate that is being used for energy at rest and during exercise, and depending on the exercise intensity, this ratio can and will change.
You and Ric both have valid points, but the subject of the post is "Burning Fat Calories" and we seem to have gotten into "Weight Loss (i.e. where total calories, not just fat, comes into play)."
If you want to focus on burning the most fat calories, you will need to ride at a moderate intensity for the longest amount of time you have available. At intensities up to about 65% of VO2 max, fat is the preferred fuel that is oxidized for energy. While there is still energy provided by carbohydrate oxidation, fat is the preferred fuel for moderate intensity exercise. As you go above 65%, the rate of fat oxidation begins to fall and the % of carbohydrate (blood glucose, muscle, and liver glycogen) that is oxidized for energy gradually increases. Ric's comment was slightly off when he said that "If you are therefore try to maximise fat loss, you should aim to exercise at the highest intensity that you can for the duration of the time you have available and that, that allows recovery for the next consecutive training session." (This comment would fit in better in the next paragraph).
If you want to talk about total caloric expenditure (for weight loss), then the highest intensity you can maintain for the longest period of time is best. This will cause you to consume the most oxygen, and as long as you can maintain the intensity, you'll burn the most calories. For weight loss, where the calories come from isn't as important as the fact that they're being used.
Hope this helps!
Unfortunately there is no way to do this. If you get tested in a lab where you have your gases (not THAT gas!962817 said:
) analyzed (O2 and CO2), you can see what's called a Respiratory Quotient that shows you about how much fat vs. carbohydrate is being used for energy. The RQ = VCO2/V02, so as you get into higher intensities and start to blow off more CO2 (i.e. getting close to hyperventilating as you exercise harder and harder), then you're using more and more carbohydrate for energy, where as if you stay in the lower intensity, the CO2 in the expired air will be lower than the O2, and you'll see an RQ closer to .80 or .90 (approximately). If you have an RQ over .98, and especially over 1.00, then you're going into that zone where you will burn more carbohydrate than fat for energy.
This is kind of what I was looking for. Not exactly the graph I was hoping for, but it's a nice table.
Do the levels of fat burned change if you ride in a glycogen-depleted (fasting) state such as in the morning versus in the evening? I assume that if you ride after eating that you would primarily be burning glycogen and then fat once the glycogen is depleted.Orange Fish said:
Wow, on one ride you actually gained weight! Were you riding backwards on that one?JTE83 said:
We have some breakfast group rides around here where it is possible to gain weight while riding. Really though, a pound of fat is worth about 3300 calories, so the calories expended on most of those rides don't justify the amount of weight loss that was measured. I'd guess that water loss would be significant enough to mask any actual loss of body fat on any specific ride. That chart clearly shows a successful long-term weight loss regime, though. Congrats!
Now we're getting into the fasted vs. fed areas. If you ride fasted, your body will just have less to work with basically. Usually your body will be able to regulate blood glucose and muscle/liver glycogen levels by interconverting protein and/or fat as needed to maintain homeostasis. So you won't necessarily burn more glycogen or fat as you deplete your stores. A few things may happen.962817 said:
#1 you probably won't run out of fat stores because we have thousands of calories of fat at our disposal.
#2 as you become depleted, you won't be albe to maintain the appropriate intensity for whatever training you're doing and will slow down as needed anyway because your body won't be able to burn any more glycogen (if you're depleted) and it won't be able to yield energy fast enough from fat, so your inensity will have to drop because you'll need to consume more O2 to help the conversion of fat to energy.
frenchyge said:Wow, on one ride you actually gained weight! Were you riding backwards on that one?
Really though, a pound of fat is worth about 3300 calories, so the calories expended on most of those rides don't justify the amount of weight loss that was measured. I'd guess that water loss would be significant enough to mask any actual loss of body fat on any specific ride. That chart clearly shows a successful long-term weight loss regime, though. Congrats!
I use a Polar S720i for my calorie and HRM measurements. My weight the next day in the morning after a pee is compared to the day before with the ride to determine my weight loss. Factors such as eating too much after a ride may have resulted in a weight gain, but mostly - I don't overeat. I can't explain why on some long distance rides I don't lose weight. I'm now switching to "mixed" training where I do 7 mile laps a low HR (~80%) and then other laps at higher HR (~87% MHR) or with intervals. That way I get fat burning and speed training. My weight loss results are definitely not water, and I do drink a lot of water during rides. I think Polar's calorie expenditure is not accurate based on my weight losses.
Thanks for your reply.Orange Fish said:If you want to talk about total caloric expenditure (for weight loss), then the highest intensity you can maintain for the longest period of time is best. This will cause you to consume the most oxygen, and as long as you can maintain the intensity, you'll burn the most calories. For weight loss, where the calories come from isn't as important as the fact that they're being used.
Hope this helps!
First, I didn't mean to use absolutes in my arguments (although in hindsight I can see that I did speak in absolutes when I talked about all calories coming from glycogen).
Second, I totally agree that weight loss is the result of total calories consumed minus total calories expended.
Third, I must confess that I am not an expert on this subject, and I'm not saying that my reasoning is correct, but I have not seen the arguments yet to convince me that I am wrong.
So... I will still argue that it is better to train at lower intensities also when the goal is weight loss. I am arguing that where the calories come from does matter.
My point is that glycogen is a finite energy store that has to be filled up once you have used some of it.
Let's say you eat and expend 2500kcal a day when you don't train. Then there's no weight loss. We agree on that.
The next day you eat 2500kcal as usual, but in addition, you do a 1 hour high intensity workout. Let's say you expend 1000kcal, with 800kcal coming from glycogen and 200kcal from fat (these are just example numbers). That day you have consumed your 2500kcal, but you have expended ~3500kcal because of your workout. Now, I argue that you can not conclude that there has been a weight loss corresponding to 1000kcal. You are in glycogen debt, and this debt will have to be repaid! If not today, then later.
Lets say you repeated the regime described above one more day. You will then have achieved a calorie deficit of 2000kcal over the two day period, but at the same time you have depleted your glycogen stores with 1600kcal.
Anyone who has been glycogen depleted knows that you can not complete even lower intensity workouts when you have run out of glycogen.
It will simply not be possible to repeat this over a longer period of time.
At some point in time you will have to refuel those 1600kcal of glycogen, bringing your total energy intake on the inevitable "refuelling day" up to 2500kcal+1600kcal=4100kcal. You will however, still have lost the 400kcal that came from fat utilization.
Unless there is some kind of shift in metabolism is favor of fat occuring when you deplete you glycogen stores, I can not see why the above is not true.
Riding after fasting will just cause one to bonk earlier. That'll keep them from working harder and burning more calories, which is what needs to be done.962817 said:
I think Ric once said that the ideal fat burning zone was sitting on the couch watching TV as those are the conditions when a person burns the highest fat/glycogen percentages. Works for me. Where's my remote?!
I believe the body will continue to metabolize it's own fat and protein stores to replenish the glycogen stores that have been depleted. You don't *have* to eat more to refill your depleted stores, but you'll probably feel like total **** while you're waiting for your energy to come back on its own.Aaberg said:
You're thinking is mostly correct, though, that optimal weight loss is much more complicated that just "____ intensity will produce the best weight loss." Even though caloric debt is the driving mechanism, there are other factors such as:
1) how much time is available for exercise, and how often?
2) does exercising above a certain intensity force a person to miss out on available exercise time for recovery?
3) does exercising below a certain intensity generate boredom (ie, less fun)?
4) does exercise above a certain intensity make the person want to quit or look for excuses not to exercise (ie, less fun)?
5) high-intensity exercise can promote severe hunger cravings due to glycogen depletion. How much can be withstood before the person starts to increase their calorie intake above their baseline?
I believe that exercising as much as possible, at an intensity that is considered "fun" is the way to make the program stick long enough to achieve the desired results. What that means is highly dependent on the individual, though.
Agreed. Weight loss occurs when the number of calories expended exceed the number of calories consumed:Aaberg said:
Calories consumed > Calories expended --> weight gain
Calories consumed < Calories expended --> weight loss
Calories consumed = Calories expended --> weight maintenance
Research has shown that exercise at 65% of VO2 max will use fat as the primary energy source, while carbohydrate becomes more and more the preferred source at increasing intensities above 65%.
Weight loss depends on total caloric expenditure, not total fat expenditure. If you consume more Oxygen by exercising more inensely, you burn more calories, hence weight loss. I'm not sure how else to say this. I have my masters degree in sports nutrition, so what I'm telling you is no joke. I've seen the research and I know what works.
Right. Glycogen is finite and we only have a relatively small amount stored in muscle and liver when compared to fat storage in our bodies. And after exercise we need to refuel those stores because glucose is an extremely important energy source for nearly every tissue of the body. That's why post-exercise we should consume carbohydrate, whether it's in the form of a sports drink, pasta, or whatever.
Agreed.
Ok, a 1 hour high-intensity workout. I'll consider high-intensity 85% of VO2 max.
Where do you get the ~3500kcal expended in one workout? That's not going to happen in a 1 hour high-intensity ride.
The typical body can store approximately 350 grams of carbohdyrate in the form of glycogen, which works out to 1,400kcal, so with a high-intensity workout of 1 hour, you MAY come close to depleting your glycogen stores, but I wouldn't bet my last dollar on it. Remember, you will never burn ALL glycogen, so in that 1 hour, you will have a time when fat is the preferred fuel and will be providing 50% or more of the energy required to get you up to that higher intensity.
Regarding your last point in that paragraph, I NEVER concluded that there was a weight loss corresponding to 1000kcal. There may be a total caloric deficit of 1000kcal due to that workout, but I never said anything about weight loss due to this workout. Weight loss must occur over time, not in one workout.
About the glycogen debt, you're right. It will have to be repaid, and this should be easy in the post-workout meal and normal diet thereafter.
Is this assuming we're not eating for those two days?
This "refuelling day" is what makes me wonder if you're considering that the person even had a post-exercise meal and is continuously eating after that meal through the next day and after this second workout.
If we deplete glycogen stores and enter the "fasted" state, then there will be interconversion of the macronutrients (fat, carbohydrate, protein) primarily in the pathway of gluconeogenesis (generation of new/more glucose) so that we can provide the body with the required amounts of glucose to continue functioning properly.
As for fats, the glycerol portion of the fats can be converted back into glucose via DHAP in a reverse reaction (the reverse of glycolysis).
However, I don't see how this arguement holds true to anything we're talking about here since, as cyclists, we KNOW that we need to refuel our bodies with a post-exercise meal that is rich in carbohydrates. So if we talk about 2 days of working out in a glycogen depeleted state (unless it's dealing with carbohydrate loading), then it's just a silly arguement.
If we become depleted of glycogen stores and enter a "fasted" state, some fat (the glycerol portion at least) in our bodies will be used to "make" new glucose since glucose is extremely important for bodily functions and since we simply cannot live without it.
AND they'll impede the recovery process ... AND their immune system will take a dump. Hardly worth it if you ask me.frenchyge said:
What ever happened to sensible weight loss, Frechyge? Is everyone looking for a gimmick, a magic formula or a McDiet these days?
