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  1. #1
    . . . rosebud . . . Diggy18's Avatar
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    Effects of Cold on Metabolism

    Maybe this goes better in the Training and Nutrition Forum, but anyways:

    1) Is it true that you will burn significantly more calories riding in cold weather? (Will I have to eat more on my rides?)

    2) Is it true that the body's metabolism naturally slows down and tries to make more fat as the temperature drops and daylight decreases?

  2. #2
    無くなった HereNT's Avatar
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    I believe both are true, but have no actual evidence. For 1, it only makes sense - you have to burn calories just to stay warm, then you are riding on top of that. For 2, it seems like thats how most mammals work, so I'd imagine humans aren't much different...

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    My Bike Journal Profile

    Oh, you hate your job? There's a support group for that, it's called EVERYONE and they meet at the PUB!

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    Bike Happy DanFromDetroit's Avatar
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    I can't read the link above, it seems to be blocked by the corporate firewall.

    I have no evidence either but this is what I have heard.

    1. You don't burn more calories because it is cold. Remember you are dressed in clothing. If you burn calories because it is cold, the way that is done is by shivering. If you are shivering, then you have already gone wrong.

    2. Your metabolism doesn't slow down, but your activity level might. If it is cold and unpleasant outside, you would tend to spend less time there and be less active.

    Dan
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    Quote Originally Posted by DanFromDetroit
    I can't read the link above, it seems to be blocked by the corporate firewall.


    Dan
    Here is what it says.


    Does the cold weather make it harder to get in shape?
    Print Report | Bookmark

    Now that winter is well and truly here (in England, at least), I've had a few questions from people wanting to know whether the cold weather makes it harder to get in shape.

    I think it does.

    This depends, of course, on where you live. What you're about to read assumes that it gets colder and darker in the winter, and lighter and hotter in the summer.

    You see, there's plenty of research to show that your body will respond very differently to the same program of diet and exercise in the summer than it does in the winter.

    Here's why...

    Firstly, the temperature in which you exercise affects the number of fat calories your body burns for energy. Some evidence for this comes from a trial published in the journal Medicine and Science in Sports and Exercise [5]. Nine male subjects cycled for 90 minutes in several different temperatures.

    Minus 10 degrees Celsius

    0 degrees Celsius

    10 degrees Celsius

    20 degrees Celsius

    The number of fat calories burned for energy was reduced at both minus 10 degrees Celsius (0.15 grams of fat per minute) compared with 10 degrees Celsius (0.35 grams of fat per minute) and 20 degrees Celsius (0.40 grams of fat per minute). Previous research at Kent State University also shows an increase in protein breakdown when you exercise in the cold [1].

    This is not the only study to look at the effect of cold air on fat metabolism. And the results are far from conclusive. In fact, during submaximal exercise in the cold, fat metabolism has been reported to be elevated, unchanged or reduced.

    Other studies have combined whole body precooling before the exercise. This can reduce core body temperature, leading to a "shivering" response. It might explain why some trials show that the cold actually increases the amount of fat burned for energy.

    In this study, the normal rise in core temperature associated with exercise stopped the subjects from shivering. That's why I think it's more relevant to people like you and me who exercise regularly.

    Skin temperature also affects growth hormone levels. In fact, simply taking a hot (38-39 degrees Celsius) bath for 25 minutes will raise growth hormone levels more than ten-fold [4].

    A single surge in growth hormone increases both the number of fat calories your body burns for energy and your metabolic rate [3]. That's why growth hormone therapy often leads to a reduction in fat mass (but it doesn't mean you can lose fat sitting in the bath sorry).

    Hibernation

    Hibernating animals (those that sleep during the winter) tend to store fat before they hibernate. One of the ways they accomplish this is via an increase in the activity of enzymes (such as lipoprotein lipase, known also as LPL) that promote the storage of fat.

    More interesting still, LPL levels in humans also rise and fall in tandem with the seasons [2]. Researchers from the University of Colorado studied a group of 12 women and 6 men in both the summer and winter.

    Summer was classed as May through August. Winter was classed as November through February. LPL activity in both muscle and fat increased during the winter, and dropped during the summer.

    Winter also sees a change in the activity of several fat-burning and muscle-building hormones.

    For example, cortisol levels reach a low point in the summer [7]. Not only is cortisol associated with the storage of abdominal fat, it's also been linked to all kinds of health problems, including diabetes, heart disease and depression. Cortisol may also weaken your immune system, leaving you more susceptible to colds and flu.

    Testosterone, a powerful hormone which helps you build muscle and lose fat, tends to peak in the summer and early autumn. It also reaches a low point in the winter and early spring [6].

    Serotonin
    There's also evidence to show that you'll find it harder to control your appetite in the winter rather than the summer. Some studies, for instance, show a link between the "winter blues" and a drop in serotonin levels [7].

    Serotonin is a chemical that helps messages pass from one nerve cell to another. It helps different parts of your brain "talk" to each other.

    When serotonin drops below a certain level, your brain "thinks" that your body is starving and "tells" you to start eating. In fact, some researchers believe that there's direct link between obesity (due to overeating) and decreased brain serotonin levels.

    Overweight people with low levels of serotonin feel almost compelled to eat more. Once they get their carbohydrate "fix", serotonin levels rise, and they feel better again albeit temporarily.

    Dr Albert Stunkard, a professor of psychiatry at the University of Pennsylvania, thinks that people with an almost uncontrollable urge to raid the fridge late at night are doing it to help themselves sleep by boosting serotonin levels.

    In other words, some people who suffer from the "winter blues" may use foods high in carbohydrate to make themselves feel better.

    The bottom line is that many people will find it harder to get in shape in the winter rather than the summer. This is normal. During the winter months, it's perfectly reasonable to expect a slower rate of fat loss and muscle gain.

  6. #6
    You need a new bike supcom's Avatar
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    Quote Originally Posted by Diggy18
    Maybe this goes better in the Training and Nutrition Forum, but anyways:

    1) Is it true that you will burn significantly more calories riding in cold weather? (Will I have to eat more on my rides?)

    2) Is it true that the body's metabolism naturally slows down and tries to make more fat as the temperature drops and daylight decreases?
    Any effects of cold on metabolism are likely to be minor to insignificant and I would not be concerned about it. The biggest effect cold has on metabolism is it reduces the incentive to get off the couch and exercise.

  7. #7
    Packfodding 3 caloso's Avatar
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    Quote Originally Posted by supcom
    The biggest effect cold has on metabolism is it reduces the incentive to get off the couch and exercise.
    Damn straight.
    Cyclists of the world, unite! You have nothing to lube but your chains!

  8. #8
    DEADBEEF khuon's Avatar
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    Quote Originally Posted by caloso
    Damn straight.
    Tell me about it. I usually don't catch colds. Sometimes I will not feel right but I can function fine and it goes away pretty quickly. But when I do come down with something, it knocks me out for weeks. I managed to succumb to a nasty bug last week and it's taking all my energy just to get in some actual work during the day. Afterwards, I'm totally wiped. Between my business travel and my recent illness, I haven't had more than a couple of days on the bike in the past month. Hopefully this stuff will pass soon but I also dread getting back on the bike after such a lapse.
    1999 K2 OzM 2001 Aegis Aro Svelte OCP Club Member
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  9. #9
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    Quote Originally Posted by Diggy18
    Maybe this goes better in the Training and Nutrition Forum, but anyways:

    1) Is it true that you will burn significantly more calories riding in cold weather? (Will I have to eat more on my rides?)

    2) Is it true that the body's metabolism naturally slows down and tries to make more fat as the temperature drops and daylight decreases?
    I was thinking about this thread on my ride today. While it wasn't really all that cold (30's F) it was VERY windy. The wind was 20-40 MPH out of the North. I don't know if the metabolism actually changes but it usually is a LOT more work to ride in the cold. That should translate into burning more calories.

    The bike and your body just don't want to go in the cold. It simply takes more effort to go. I had a horrible average speed of like 11.8 mph. It took me nearly 2 hours to go 22.xx miles on my mountain bike. Granted the wind was most of the problem, but my times slow in general when it is cold out. Subsequently, i am on the bike longer and presumeably pedalling more and burning more calories.

    On top of that i am way more tired right now than normal. I ride at least that many miles every day and am usually not tired at supper time. Right now i could go to bed.

  10. #10
    . . . rosebud . . . Diggy18's Avatar
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    For sure the wind makes you work harder and takes more out of you. I noticed too that a sustained wind won't annoy me since it's blowing all the time and I just forget that it's there, whereas gusts of wind bug the heck out of me since all of a sudden the wind makes it hard to go. However, the constant wind definitely makes me more tired at the end of the ride. It's like I don't realize it until a coupe hours after the ride, and then boom, I'm wondering why I'm so worn out. Had that happen last Saturday on 57 mile ride.

  11. #11
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    I am used to wind. That is part of the game. It is wind and cold that I am speaking of. The combo is like a jab followed by a devastating uppercut. I can handle wind and i can handle cold. I can even handle cold and wind like today. It just makes me more tired.

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    One effect of cold weather that no one has mentioned, and that is that your muscles tend to tighten when your limbs get cold. I no longer commute to work, but when I did I would get cramps in the evening when the weather turned cold in the late fall. It took me a long time to figure out why. I think the muscles may acturally shorten and fatten to conserve heat. I am only guessing at that cause.

  13. #13
    Member jgwilliams's Avatar
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    This is a topic of particular concern to me at the moment. I have always felt that my ride to work (22 miles) is much harder in Winter, even though the winds here are normally lighter. This year, for the first time, I have been using a heart-rate monitor, and the results have been quite interesting. Just lately we have had a cold snap - around 5 or 6 degrees (C that is, which is 41 to 43 in Fahrenheit) - and my average calory count according to the HRM jumped by 15 to 20%, which is a huge amount. The strange thing is, I didn't feel as if I was getting cold, so I don't really understand it. Today the temperature was closer to 10 degrees C (50 F), and my calory count was back down to my normal usage!

    I also have to say that my trousers do seem to be fitting a little tighter, but that is very subjective. It makes sense, if your body is feeling the cold, that it would redistribute the fat to try and compensate.

  14. #14
    . . . rosebud . . . Diggy18's Avatar
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    Hey that's interesting. And you have a chance to get some real empirical data! If your average calorie count increased, does that mean that your heart rate was up, too? (I guess that's how the machine calculates calorie usage, right?) Were you riding harder?

    If the average speed stays the same, see how your calorie consumption goes in relation to the temperature, and post back if you can. I'd be interested to see the results of this.

  15. #15
    Member jgwilliams's Avatar
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    Well, I was trying not to ride harder, but for the last part of my ride the HRM was bleeping away madly to tell me that I was over budget. It's because I have a tendency to just go flat out that I bought it in the first place, so I try not to ignore it when it does start bleeping. Some days it just isn't possible, though.

  16. #16
    Member jgwilliams's Avatar
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    Reading through this forum I can see that our winters here are pretty mild compared to what some of you guys cycle through. I have one problem, though, that doesn't seem to have been addressed by any of the questions here. Why is it that in cold weather I seem to have problems lasting my whole journey to/from work (around 90 minutes) without taking a leak? I normally have pretty good bladder control, but during cold weather I have to make sure I've squeazed everything out before I set off, or risk ending my journey in extreme discomfort.

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