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Efficient Fat Burning
What does it mean, exactly, when the body is said to become more efficient at burning fat? Does it mean that the body burns more fat or less fat? "Efficient" could mean "less fat" in the same way that fuel efficiency in cars means *less* fuel used for the same distance. Thus, the more "efficient" our bodies become at using fat, the more intense our workouts have to be to burn the same amount as before! But that's semantics...what's the actual physiology?? |
#2
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Efficient Fat Burning
On Jan 21, 11:54*pm, Prisoner at War
wrote: What does it mean, exactly, when the body is said to become more efficient at burning fat? Does it mean that the body burns more fat or less fat? "Efficient" could mean "less fat" in the same way that fuel efficiency in cars means *less* fuel used for the same distance. *Thus, the more "efficient" our bodies become at using fat, the more intense our workouts have to be to burn the same amount as before! But that's semantics...what's the actual physiology?? Yes. |
#3
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Efficient Fat Burning
"Prisoner at War" wrote in message ... What does it mean, exactly, when the body is said to become more efficient at burning fat? Does it mean that the body burns more fat or less fat? "Efficient" could mean "less fat" in the same way that fuel efficiency in cars means *less* fuel used for the same distance. Thus, the more "efficient" our bodies become at using fat, the more intense our workouts have to be to burn the same amount as before! But that's semantics...what's the actual physiology?? For the physiology, I think Gary Taubes' "Good Calories, Bad Calories" may help. The phrase seems ambiguous to me, thus, might need contextual clarification. |
#4
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Efficient Fat Burning
On Jan 22, 11:36 am, "Cubit" wrote:
For the physiology, I think Gary Taubes' "Good Calories, Bad Calories" may help. The phrase seems ambiguous to me, thus, might need contextual clarification. Indeed! But it's such a popular sentiment, and when I just read it again in "Runner's World Complete Book of Running" I just had to ask and find out, once and for all...the usual context appears to suggest that our bodies burn more fat as it becomes more "efficient," though I've also read somewhere (Noakes?) that being more efficient means that less calories are burned for the same work.... |
#5
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Efficient Fat Burning
"Prisoner at War" wrote in message
... What does it mean, exactly, when the body is said to become more efficient at burning fat? Does it mean that the body burns more fat or less fat? Without context, it's difficult to know, but it seems a poor choice of wording. During aerobic exercise, it is *more* efficient to burn *more* fat because that means that you're burning less glycogen, and glycogen is much more scarce than fat (you only have ~400gm of it and that only provides as much energy as about 200gm fat) This is fairly basic stuff -- any book on exercise physiology or endurance training will discuss it. Cheers, -- Elflord |
#6
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Efficient Fat Burning
On Jan 21, 8:54*pm, Prisoner at War wrote:
What does it mean, exactly, when the body is said to become more efficient at burning fat? Efficiency refers to how high a yield of some desired output we obtain relative to some costly inputs to some process. There is always some frame of reference defined by human values which determine what efficiency means in that context. E.g. the efficiency of a computer program is how much calculation it gets done in a given amount of time. Time is a costly input to the process, the result is the deisred output. The energy efficiency of computation is important: we want CPU's to use less electricity, while still running fast. The efficiency of an engine is how much work you obtain from the energy source, such as fuel. The energy that doesn't become work is wasted as heat. Heating can be efficient also. Heating a poorly insulated home is less efficient than heating an insulated one. Maintaining the place at a given temperature (the benefit) requires more input (energy) if heat escapes easily. When heat is easily available (basically, is already the waste from another process), you don't care about heat efficiency. A big engine can easily heat the interior of a car, even if the car is poorly insulated. The heat is produced even if you don't use it for heating, so wasting it doesn't matter. To be more efficient at burning fat, it means that the body gets rid of fat (the desired effect of the process) with less effort (the costly input). Effort consists of diet and exercise. So the claim that a body is more efficient at burning fat means that it can shed body fat with less exercise and less dieting effort than an inefficient body. But that's semantics...what's the actual physiology?? The actual physiology is fat mobilization. The difficulty in losing fat isn't actually burning it, but getting it to march out of the fat cells and into circulation. Think about it; you could easily consume a pound of butter over the next week, without putting any of it on as fat. You could not with equal ease get a pound of fat to leave your adipose tissue, particularly if you're already lean. But if you could mobilize a pound of fat, it would be as easily burned off as that pound of butter. |
#7
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Efficient Fat Burning
Dnia 2008-01-22 Elflord napisał(a):
"Prisoner at War" wrote in message ... What does it mean, exactly, when the body is said to become more efficient at burning fat? Does it mean that the body burns more fat or less fat? Without context, it's difficult to know, but it seems a poor choice of wording. During aerobic exercise, it is *more* efficient to burn *more* fat because that means that you're burning less glycogen, and glycogen is much more scarce than fat (you only have ~400gm of it and that only provides as much energy as about 200gm fat) That would be liver alone, AFAIR. Most of glycogen is stored in muscles and it takes a while to burn it all. I remember reading about glycogen depletion workouts (recent fad in some sport related training regimes) and it took quite an effort to burn it all, plus some fasting too. Fat isn't good fuel source for aerobic workouts, because it needs more oxygen to use it. IOW you get winded more easily and overall intensity must go down (a lot). This is fairly basic stuff -- any book on exercise physiology or endurance training will discuss it. I'm missing context too, so it could be that I write about unrelated topic. Anyway, we have more than 400mg of glycogen and fat is bad fuel for intense aerobic activity. Your body will use it, if it has no choice, but your training will be lousy. -- Andrzej Rosa 1127R |
#8
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Efficient Fat Burning
On 2008-01-22, Andrzej Rosa wrote:
During aerobic exercise, it is *more* efficient to burn *more* fat because that means that you're burning less glycogen, and glycogen is much more scarce than fat (you only have ~400gm of it and that only provides as much energy as about 200gm fat) That would be liver alone, AFAIR. Most of glycogen is stored in muscles and it takes a while to burn it all. I don't think so. We enough to cover about 2hrs of hard running -- that's a bit over 2000 calories. That's where the "hitting the wall" theory came from -- you don't have enough glycogen to run a marathon without using some fat. I remember reading about glycogen depletion workouts (recent fad in some sport related training regimes) and it took quite an effort to burn it all, plus some fasting too. Fat isn't good fuel source for aerobic workouts, because it needs more oxygen to use it. Without qualification, it's hard to say whether it's a "good" fuel source for aerobic workouts. It's "good" in the sense that it's abundant, but "bad" in the sense that it doesn't provide energy as quickly. Any kind of speed work depends heavily on glycogen stores, because intensity is key. But at least for longer events (e.g. 2hrs+), it is advantageous to be able to metabolise fat as quickly as possible, because fat is abundant whereas glycogen is not. IOW you get winded more easily and overall intensity must go down (a lot). This is fairly basic stuff -- any book on exercise physiology or endurance training will discuss it. I'm missing context too, so it could be that I write about unrelated topic. Anyway, we have more than 400mg of glycogen and fat is bad fuel for intense aerobic activity. Your body will use it, if it has no If you're doing the exercise for any purpose besides competing in endurance events, I'd agree. People competing in endurance events can and should do base training to address this. Cheers, -- Elflord |
#9
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Efficient Fat Burning
On Jan 22, 12:02*pm, Elflord wrote:
"Prisoner at War" wrote in message ... What does it mean, exactly, when the body is said to become more efficient at burning fat? Does it mean that the body burns more fat or less fat? Without context, it's difficult to know, but it seems a poor choice of wording. During aerobic exercise, it is *more* efficient to burn *more* fat because that means that you're burning less glycogen, and glycogen is much more scarce than fat (you only have ~400gm of it and that only provides as much energy as about 200gm fat) That's different. The desired result during this type of sport is (for instance) to go the farthest in the least amount of time, not to lose the most adipose fat with the least effort. You can't discuss the efficiency of a process without knowing what the important result that that process must yield, and what input resources are to be optimized. |
#10
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Efficient Fat Burning
Dnia 2008-01-22 Elflord napisał(a):
On 2008-01-22, Andrzej Rosa wrote: That would be liver alone, AFAIR. Most of glycogen is stored in muscles and it takes a while to burn it all. I don't think so. We enough to cover about 2hrs of hard running -- that's a bit over 2000 calories. That's where the "hitting the wall" theory came from -- you don't have enough glycogen to run a marathon without using some fat. That 2 hours of hard running rings true, so it may be that I mixed the numbers (that is miligrams with calories). [...] I'm missing context too, so it could be that I write about unrelated topic. Anyway, we have more than 400mg of glycogen and fat is bad fuel for intense aerobic activity. Your body will use it, if it has no If you're doing the exercise for any purpose besides competing in endurance events, I'd agree. And endurance events, which take more than 2000 cal to finish. Most of them is way shorter. Even ten miles run should be safely within the limits of our glycogen stores. [...] -- Andrzej Rosa 1127R |
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