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  1. #1
    Making a kilometer blurry waterrockets's Avatar
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    How to figure fat Calories burned in WKO+?

    I'm going to embark on a 6-week weight loss cycle starting next week. For a given ride, is there an accepted power threshold for fat burning? It seems like all the active recovery, endurance, and maybe the bottom of tempo zones would be fueled by fat.

    So, it seems like a spreadsheet could be used to look at a power file from a ride and integrate over the power distribution to come up with a calories from fat estimate. For a given power level, take it's % of time from the ride and figure how many kJ were burned up at that level, and so on...

    Has anyone done this, or is there an easier way to do it?

  2. #2
    RacingBear UmneyDurak's Avatar
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    Ehh just ride a lot. Having a powermeter will help in determining how many calories you burned, at that point adjust your diet accordingly.
    Although at lower intensities you do burn higher percentage of fat, you also don't burn as many calories total. At higher intensities you burn more carbohydrates, but you also expand more energy so you burn more total calories. Plus part of the food you eat will be used to replenish your glycogen stores. Also side benefit of riding at higher intensity is that it boosts your metabolism slightly. So you end up burning 200-300 (don't remember exact number) calories. Problem with higher intensity is that you just can't keep it up for long, so you need to find a good balance: LSD! Which is Long steady distance.
    I see hills.... Bring them on!!!
    Stay calm and bring a towel.

  3. #3
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    Come one, WR....calories burned > calories eaten = weight loss.
    If you are incorporating your weight loss period with a base period, just ride what you would and adjust caloric intake to lose the desired weight.

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    Making a kilometer blurry waterrockets's Avatar
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    It's not that simple. When I'm training normally, I can't limit my intake carefully enough to lose weight. I need to cut intensity so I'm not looking at the refrigerator through glycogen-starved eyes.

    I've been the same weight for three years, and my training has increased significantly in 2008. No weight loss. I tried cutting some Calories and was rewarded with bonking on 60 minute training rides.

    So, what is that threshold between carb burning and fat burning? At the Coggan endurance/tempo line?

  5. #5
    Killing Rabbits
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    There is no distinct cutoff, it is a continuum. You can see that even at very low exercise intensity some plasma glucose is being used and at moderate intensities both muscle glycogen and plasma glucose is used. Only at fairly high intensities is the contribution from free fatty acids and muscle triglycerides reduced.

    If you think about it I'm sure you can figure out a way to use IF and total KJ to come up with a good guess as to fat kcals burned.


  6. #6
    Killing Rabbits
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    Also

    Fat metabolism in exercise.
    http://www.ncbi.nlm.nih.gov/pubmed/9...ubmed_RVDocSum
    At the start of low intensity exercise, lipolysis increases further, thereby providing sufficient FFA to provide energy substrates in excess of requirements. However, lipolysis does not increase further as exercise intensity increases, and fatty acid oxidation becomes approximately equal to the total amount of fatty acids available at 65% of VO2 max.

  7. #7
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    t's not that simple. When I'm training normally, I can't limit my intake carefully enough to lose weight.
    I can't drop weight in season either..and from everything I've read you really shouldn't. Training intensely + calorie deficit = bad results. It's pretty common knowledge that you burn more fat as a percentage of cals burned at lower intensities, but like Enthalpic said, it's a continuum and also somewhat dependent on the individual.

    I'm planning on doing the same thing now that the season is over and for me, I expect my ideal zone to be mid Z2 to low Z3. You shouldn't be bonking if you are eating appropriately on the bike and around your rides.

    I've been the same weight for three years, and my training has increased significantly in 2008. No weight loss.
    Has your body composition changed? What's your bodyfat %?

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    Quote Originally Posted by Enthalpic View Post
    Also

    Fat metabolism in exercise.
    http://www.ncbi.nlm.nih.gov/pubmed/9...ubmed_RVDocSum
    At the start of low intensity exercise, lipolysis increases further, thereby providing sufficient FFA to provide energy substrates in excess of requirements. However, lipolysis does not increase further as exercise intensity increases, and fatty acid oxidation becomes approximately equal to the total amount of fatty acids available at 65% of VO2 max.
    nice find

  9. #9
    NeoRetroGrouch
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    Quote Originally Posted by waterrockets View Post
    I'm going to embark on a 6-week weight loss cycle starting next week. For a given ride, is there an accepted power threshold for fat burning? It seems like all the active recovery, endurance, and maybe the bottom of tempo zones would be fueled by fat.

    So, it seems like a spreadsheet could be used to look at a power file from a ride and integrate over the power distribution to come up with a calories from fat estimate. For a given power level, take it's % of time from the ride and figure how many kJ were burned up at that level, and so on...

    Has anyone done this, or is there an easier way to do it?
    I would say:
    Below LT (95% FTP? or is it the other way around??) figure 200 Cal/hr from fat - rest carbohydrates.
    Above LT, all carbohydrates.

    This should get you in the ball park. If you bonk, adjust slightly and keep trying. If you never bonk, try 225/hr from fat.

    TF

  10. #10
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    Quote Originally Posted by waterrockets View Post
    It's not that simple. When I'm training normally, I can't limit my intake carefully enough to lose weight. I need to cut intensity so I'm not looking at the refrigerator through glycogen-starved eyes.
    Are you sure it's the depleted glycogen that's triggering your hunger or is it due to muscle recovery after a hard workout? I've been riding and losing weight all summer. The hardest rides I do are usually 90 minutes at 90-95% of LT with no intervals. I'm sure Sat group rides deplete most of my glycogen stores but I don't really notice any extra hunger pangs. I tend to eat more when I take a day off.

    If you try and lose weight by staying in a fat burning zone you'll have to spend an awful lot more time on the bike.

  11. #11
    Making a kilometer blurry waterrockets's Avatar
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    Thanks for the replies. It looks like if I shoot for that high Z2/low Z3, I'll be safe with a modest diet.

    Body composition hasn't changed. It looks like I'm at 10% BF from the bathroom scale guesstimator.

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    IIRC, in another post you said you were around 170( and 6' plus)? Assuming the scale is somewhat accurate - and it's probably as accurate as most ways of testing - the most you should expect to drop without dropping lean mass is ~3%, or about 5 lbs. How much are you hoping to lose?

    Also, make sure you are eating for recovery when you do your longer rides and/or are riding back-to-back days. I really notice a big difference when I eat properly after a ride, especially when trying to work on a deficit the rest of the day. Carefully measure what you are eating - a kitchen scale is great. And keep track of what you are eating on the bike and adjust accordingly.
    Last edited by ottsville; 09-18-08 at 05:57 AM.

  13. #13
    Making a kilometer blurry waterrockets's Avatar
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    Quote Originally Posted by ottsville View Post
    IIRC, in another post you said you were around 170( and 6' plus)? Assuming the scale is somewhat accurate - and it's probably as accurate as most ways of testing - the most you should expect to drop without dropping lean mass is ~3%, or about 5 lbs. How much are you hoping to lose?

    Also, make sure you are eating for recovery when you do your longer rides and/or are riding back-to-back days. I really notice a big difference when I eat properly after a ride, especially when trying to work on a deficit the rest of the day. Carefully measure what you are eating - a kitchen scale is great. And keep track of what you are eating on the bike and adjust accordingly.
    I'm 182, at 6'4". I'm planning on 5lbs, hoping for 10. I'm only working on this for about 6 weeks total, then it's back to SST.

    I did my first easier ride today and could certainly tell my hunger was lower than normal. I didn't eat nearly as much as the rest of the day.

    The cool thing is that I've got one great big bundle of calories I can easily eliminate: the 14 Oreos I eat each day. I think that's ~780 Calories.

  14. #14
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    Quote Originally Posted by waterrockets View Post

    The cool thing is that I've got one great big bundle of calories I can easily eliminate: the 14 Oreos I eat each day. I think that's ~780 Calories.
    That's 6 pounds in a month right there.

    My weakness is good chocolate. But oreos with a big glass of milk are always a good treat!

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