ACSM rebuttal?

[jksinrod]

Anyone have an answer to the ACSM report bashing LC diets? They claim that carbs burn first, then muscle, then fat. If you've read it, they present scientific proof that LC diets are short term and don't work.

[GeorgeMead]

Acsm??????

[322432]

Alcohol burns first--must be the body's preferred fuel. The other explanation is that the body burns the toxic fuel first. Niether case is a good argument for carbs.

[Dodger]

Anyone have an answer to the ACSM report bashing LC diets? They claim that carbs burn first, then muscle, then fat. If you've read it, they present scientific proof that LC diets are short term and don't work.
A link to the report would be nice. ASCM = American College of Sports Medicine?

If muscle is used before fat, then all biochemistry books must be wrong. All endurance athletes would be without muscles.

Define short term. I have been on low-carb for over two and a half years and it seems to be working fine.

[jksinrod]

I'm not the basher, I'm just looking for a rebuttal. By the way I'm a 7 year Atkins guys with a permanent loss of 50 lbs.
OK sorry folks I assumed their report would be known to you. The ACSM is the American College of Sports Medicine. A group of top flight researchers. Here's the gist of it:

The reason you lose the weight is because the average body has about 10lbs of gycogen (the main thing your body uses to produce ATP ((A form of energy for the body to use))) in storage. Now each molecule of glycogen carries 2.5 molecules of water with it. So that means if you have 10lbs of glycogen then you have 25lbs of water with it totaling to about 35lbs on average. When you cut the carbs, your body isn't getting the glycogen it needs and in consequence water is now not getting into the blood cells. You just dropped 35lbs in water and glycogen, things your body most definitely needs. If the body doesn't have glycogen to use for energy it'll next go to protein before it goes to fat. So now after those 35lbs your now losing lean body mass.

[mrfreddy]

The ACSM is the American College of Sports Medicine. A group of top flight researchers. Here's the gist of it:

The reason you lose the weight is because the average body has about 10lbs of gycogen (the main thing your body uses to produce ATP ((A form of energy for the body to use))) in storage. Now each molecule of glycogen carries 2.5 molecules of water with it. So that means if you have 10lbs of glycogen then you have 25lbs of water with it totaling to about 35lbs on average. When you cut the carbs, your body isn't getting the glycogen it needs and in consequence water is now not getting into the blood cells. You just dropped 35lbs in water and glycogen, things your body most definitely needs. If the body doesn't have glycogen to use for energy it'll next go to protein before it goes to fat. So now after those 35lbs your now losing lean body mass.

so where does the ACSM crowd think humans got all these necessary carbs before ogranized agriculture, ie. before 10,000 years ago, ie. the first 2 MILLION years of our evolutionary adaptation to a diet of animal protein and fat?

I would suggest that carrying around 35 pounds of glycogen and water is not very healthy and if indeed that is the case, I for one am glad to be rid of it!

[K Walt]

I'll have to find a citation for you, but the body ONLY 'burns' muscle tissue for fuel under EXTREME starvation situations. The body is NOT that stupid, to consume itself when there are plenty of food calories coming in -- as on a low-carb way of eating.

This ASCM 'person' is dead wrong there. Just reciting myths and folklore, because low-carbing challenges some cherished faith and beliefs.

And besides many, many low-carb studies have shown that you lose MORE muscle mass on a starchy-carby 'runner's diet, than on a low-carb diet. That's consistent, and not disputed.

In addition, it's been shown that marathon runners actually burn a lot of fat, NOT exclusively glucose during their runs. In fact, the crackpot 'carbo-loading' that they do cannot increase the amount of glycygen in their tissues. Most of those loaded carbos are stored overnight as fat (about 42% saturated by the way) and burned during the race as fat. NOT as carbs.

The spokesperson is stuck in the glucose world.

[Dodger]

Jksinrod,

I checked the ASCM web site and could not find a report that seemed to be the one you are referring to. Do you know the report title and authors?

[Lisa N]

I'm not the basher, I'm just looking for a rebuttal. By the way I'm a 7 year Atkins guys with a permanent loss of 50 lbs.
OK sorry folks I assumed their report would be known to you. The ACSM is the American College of Sports Medicine. A group of top flight researchers. Here's the gist of it:

The reason you lose the weight is because the average body has about 10lbs of gycogen (the main thing your body uses to produce ATP ((A form of energy for the body to use))) in storage. Now each molecule of glycogen carries 2.5 molecules of water with it. So that means if you have 10lbs of glycogen then you have 25lbs of water with it totaling to about 35lbs on average. When you cut the carbs, your body isn't getting the glycogen it needs and in consequence water is now not getting into the blood cells. You just dropped 35lbs in water and glycogen, things your body most definitely needs. If the body doesn't have glycogen to use for energy it'll next go to protein before it goes to fat. So now after those 35lbs your now losing lean body mass.

All I can say to this is, "boloney!" and the scientific studies back it up:
http://atkins.com/Archive/2002/1/11-918650.html
http://atkins.com/Archive/2003/4/16-90624.html
http://atkins.com/Archive/2004/1/19-51552.html
http://atkins.com/Archive/2004/12/6-493360.html
http://atkins.com/Archive/2002/1/11-65155.html

[mcsblues]

I realise this is not your view jksinrod, but I thought I would add a little bit about glycogen just so you know the summary of the report you provided is nonsense from the very beginning!

- I'm sure he won't mind me posting this here, but these are the words of Gabriel Guzman posted on the Protein Power forum - (Gabe is a biochemist who actually knows what he is talking about here!)

"Q: Are muscle glycogen levels kept relatively constant? Meaning, is there a 'set' level of glycogen that the muscle and liver likes to keep in stock, so to speak? Or is it purely a function of how much carbohydrate you eat?

A:Yes, there is a level of glycogen in the muscle that is always kept. Although we normally talk about "glycogen depletion", in the case of the muscles, which is where most of the glycogen is stored, their content fluctuates less markedly than that of the liver. The human body can store up to ~450 g of glycogen (THATS ONE POUND NOT TEN!), a third of that in the liver and the rest in the muscles. Is important to understand that the glycogen in the liver serves, above all, in the maintenance of the blood glucose level. Muscle glycogen, on the other hand, serves as energy reserve, and it is not involved in maintaining blood glucose levels. The reason for this is simple: muscle lacks an important enzyme that converts an intermediate into glucose. The intermediate itself cannot leave the muscles a go into the bloodstream.

Muscle glycogen is never completely degraded. So, let's say that the muscle can store up to 300 g of glycogen, at least two thirds of that remain fairly constant. Extreme situations such as prolonged fast (true starvation) results in the depletion of protein, rather than glycogen (remember that glucose produced from glycogen canot leave the muscle).

Q: Is there a blood test or some other way to measure glycogen state?

A: I don't think you can measure glycogen state in a blood test. Glycogen is never free in the blood stream. However, it is possible to measure the rate of glycogenesis and glycogenolysis (the making and the breakdown of glycogen, respectively). There is also a recent breath test that measures liver glycogen oxidation. I think these tests are normally useful in the assessment of diseases related to glycogen storage or utilization.

Q: Does carbohydrate loading actually increase the amount of glycogen available? Or is there a maximum amount of glycogen 'space' as it were?

A: That has always been debated. Since the liver content of glycogen is the one that fluctuates the most, that is the one that is synthesized first in the well-fed state. Now, this assumes that there is enough carbohydrate in the diet for glycogen synthesis. Muscle glycogen reserves, since they don't fluctuate that much, are not likely to be altered by carbohydrate loading. This, of course, needs to be put in the right context, and here one needs to distinguish between those who constantly put an energy demand in their muscles and those who are sedentary. Sedentary people rarely deplete their muscle glycogen and since there is always a "base line glycogen", probably not even very active people can completely deplete their muscle reserves of glycogen. So, it is the liver reserves the ones supplied first. After that requirement is met, and since the muscles replenish only a fraction of what they already have, excess carbohydrate doesn' go into glycogen synthesis but to other pathways, such as fat synthesis.

Q: I'm assuming that people who eat LC create glycogen from available amino acids, and tend to replenish their stores this way after severe exercise, perhaps slower?

A: That is only if there is a need for it. Remember that the only purpose of having glycogen is to 1) maintain blood glucose levels and 2) supply energy to the muscles. Those on a carbohydrate-controlled diet still make glycogen with whatever carbohdyrate comes in the diet (note that LC may mean different things). People who don't eat carbohydrates at all (because of geographical locacion where no carbohdyrates are availabe, for example), would supply their muscles with glucose made de novo by gluconeogenesis.

Q:I would think that humans would be engineered to provide a way to create this turbo-charging fuel even if the diet didn't contain large amounts of carbs.

A: Precisely, and gluconeogenesis is one such mechanism. Evolutionary, it is important that the muscles always have some glycogen that they can use for a quick, but powerful, production of energy. That could be the difference between life and dead in a hunter-prey situation. For example, think of an animal that's feeding. It could be us sitting next to a nice fire or a deer grazing. The metabolic status in which feeding stimulates insulin release would at the same time shut down those pathways controlled by glucagon. However, if a predator appears, the animal should be able to flee the site and for that it needs a powerul generation of energy to run, thus it is necessary to have glycogen available for quick glycogenolysis, which in turn produces glucose that is used by the muscles. For liver glycogen to be replenished, it's not necessary to load excess carbohydrate."

The whole thread is here if you are interested;
http://bbs.eatprotein.com/viewtopic.php?t=3308&highlight=glycogen

Cheers,

Malcolm

[dstartz]

If muscle is used before fat, then all biochemistry books must be wrong. All endurance athletes would be without muscles.

As part of my long distance bicycling training I did 2 days of sprint training in addition to my 3 days of distance riding each week. (Sa & M 15 miles w/sprints ; W 50-60 miles; Th 25 miles slow twiddle to deplete lactic acid build up.)

Unless endurance athletes do interval training as part of their overall training they will, in fact, become basically unmuscular (look at long distance runners, for instance) because the body will canabolize muscle for energy in stable speed training. Sprinters and similar atheletes use glycogen from the liver first and then metabolized fat as their energy source.

Check out info on HIIT (High Intensity Interval Training) for more info on this subject.

[mcsblues]

As part of my long distance bicycling training I did 2 days of sprint training in addition to my 3 days of distance riding each week. (Sa & M 15 miles w/sprints ; W 50-60 miles; Th 25 miles slow twiddle to deplete lactic acid build up.)

Unless endurance athletes do interval training as part of their overall training they will, in fact, become basically unmuscular (look at long distance runners, for instance) because the body will canabolize muscle for energy in stable speed training. Sprinters and similar atheletes use glycogen from the liver first and then metabolized fat as their energy source.

Check out info on HIIT (High Intensity Interval Training) for more info on this subject.

Hmmm, while I have no intention of taking my exercise regime to your extremes :), I would have to disagree here. Whilst all athletes "use up" available glycogen first, sprinters are one class of athlete who will probably perform better on higher carbs because the conversion of metabolised fat for energy is not fast enough for the sort of explosive bursts they require. Endurance athletes on the other hand, if they adjust to a low carb diet* have been shown to improve their performance by utilising fat as the predominate energy source. Another benefit of this option is reduced lactic acid production (a byproduct of glucose metabolism.)

*http://www.nutritionandmetabolism.com/content/1/1/2

Cheers,

Malcolm

[dstartz]

Check out:

http://www.sport-fitness-advisor.com/energysystems.html

and

http://www.firstendurance.com/glutamine_essential_amino_acid.html

[mcsblues]

Half Marathon
Without doubt the aerobic system makes the greatest contibution to this event. The other two energy systems will predominate during the first minute or so of the race and in a sprint finish.

What determines whether the athlete is 'burning' carbohydrate or fat during the run?

Well, as the aerobic system begins to predominate, carbohydrate (in the form of glucose and glycogen) will make the greatest contribution to energy production. If exercise intensity is relitively low, fat will be relied on more and more as the duration increases. Again the body doesn't suddenly switch from one substrate to another, the cross over is a gradual shift.

If exercise intensity is relatively high the body will continue to rely predominantly on carbohydrate.

As a very basic summary of energy production for endurance events I don't necessarily disagree. But as Phinney (see the reference above) and many others have concluded there is a different and beneficial outcome for endurance athletes once they have adapted to a low carb diet - where the predominate source of energy for these events comes from fat. The ideal training/adaptation period seems to be 4 - 6 weeks minimum (although some benefits are seen earlier than this), after which time a low carb/high fat approach is superior.

You might like to look at Stuart Trager's experience here - he is one of the chiefs at Atkins Nutritionals - he runs marathons and iron man events on low carb. http://atkins.com/Archive/2003/11/21-571145.html

see also http://atkins.com/Archive/2002/6/17-496610.html

Cheers,

Malcolm

[Lisa N]

You might like to look at Stuart Trager's experience here - he is one of the chiefs at Atkins Nutritionals - he runs marathons and iron man events on low carb. http://atkins.com/Archive/2003/11/21-571145.html

see also http://atkins.com/Archive/2002/6/17-496610.html

You might also want to Google Stu Mittleman, an ultra long distance runner who supports an Atkins-like approach and follows it himself:
http://www.amazon.com/exec/obidos/ASIN/0062716123/103-0894006-0951852

[dstartz]

But none of these address the fact that endurance athletes eat up muscles in the course of practicing their chosen sports and those muscles, when broken down for Glutamine, then become a source of energy, thus slowing down the consumption of fat.

[mcsblues]

I think this is more likely to be as a result of specific training methods that elite athletes use for specific sports. Great marathon runners do tend to be a fairly slim (nonmuscular) build - perhaps this helps them cope with heat stress?. On the other hand, check out the calf muscles on an elite cyclist!

Cheers,

Malcolm

[dstartz]

endurance athletes eat up muscles in the course of practicing their chosen sports
I think this is more likely to be as a result of specific training methods that elite athletes use for specific sports.

""There is evidence that during times of stress the body cannot produce enough glutamine to keep up with demand which in-turn can reduce performance, immune function and reduced mood.

"Intense physical exercise drains Glutamine stores faster than the body can replenish them. When this occurs, the body breaks down muscles and becomes catabolic."
http://www.firstendurance.com/gluta...amino_acid.html


Speaking of "reduced mood", I wonder if the second wind so many endurance athletes experience is a re-elevation of mood from the body starting to catabolize muscle....

[dstartz]

BTW In case anyone is interested, I became overweight due to a fight with thyroid cancer.

I'm looking forward to the day I can get back on my beloved bike and truly ride it again. These days that's looking closer and closer....

[Lisa N]

A few more studies:

http://atkins.com/Archive/2002/1/11-376754.html
http://atkins.com/Archive/2002/1/11-488629.html
http://atkins.com/Archive/2002/1/11-534846.html

[mcsblues]

"Intense physical exercise drains Glutamine stores faster than the body can replenish them. When this occurs, the body breaks down muscles and becomes catabolic."


Yes I saw that. I think again this depends a great deal on what sort of exercise you are doing, how intense it is, how long you do it for AND what sort of diet you are on.

Glutamine like any amino acid is not just available from muscle - so even if glutamine is being used during exercise - the length of time one can do so while sparing muscle (always the body's preference) will be determined also by the stores of free amino acids - which will be influenced to a degree at least by dietary intake (or supplemenation as suggested by this article).

The other major question when it comes to endurance exercise is how intense it actually is. When "we" see a marathon runner or a cyclist in the Tour de France we are amazed (and somewhat alarmed!) at what they can do and we would be forgiven for thinking that they are exercising for long periods at an "intense" level. Well we certainly would be if we tried to keep up! - but these super athletes are for the most part not exceeding 70% of their (superior) VO2 Max (the short sprint to the finish excepted of course.). So that may explain how they can and do train on a low carb diet without their muscles wasting away.

Cheers,

Malcolm

[Dodger]

All hard exercise is catabolic. It breaks down muscle. That is why the recuperation/rest periods are important for suslce growth. If you exercise hard day after day, the body cannot rebuild muscle as fast as it is torn-down. But this doesn't mean that the muscle is being used as a primary source for fuel.

If you lift heavy weights using the same muscles day after day, you will not be getting stronger.

[dstartz]

But this doesn't mean that the muscle is being used as a primary source for fuel.
Which of us said that?