AWARE72
MuscleHead
- Oct 17, 2010
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The Fasted Cardio Roundtable
Featuring Christian Thibaudeau, Dr. Lonnie Lowery, David Barr, and Dr. John Berardi
Moderated by Chris Shugart
It's a subject that always leads to a heated debate: cardio performed in the morning on an empty stomach. Is this the fastest way to lose fat, or is it a sure way to "eat up" all that hard-earned muscle? We sat down with four T-Nation experts and decided to find out.
T-Nation: Several years ago, fasted cardio was touted as being the quickest way to drop excess body fat. The general suggestion was to wake up, drink some water, then do your cardio before eating.
But then many experts started harping about muscle loss in this state. They said that fasted morning cardio was just too catabolic. So, fasted energy systems work: good or bad? Lead us off, Lonnie!
Dr. Lonnie Lowery: From a biological perspective, fasting for a few hours or overnight does result in much lower insulin concentrations in the blood. This facilitates fat oxidation because insulin, as a necessary storage hormone, indirectly degrades the secondary messenger "cyclic AMP" within adipocytes or fat cells.
Cyclic AMP is a signal to break things down within a cell such as glycogen (stored carbohydrate in muscle tissue) and yes, triacylglycerols (stored fat in muscle and fat tissue). So in weight loss situations, well-timed lower insulin concentrations can be helpful.
There are even data suggesting that its effects linger for many hours, making the first few waking hours an advantageous target. That is, we don't always want cAMP being degraded, and prior to breakfast it won't be. This isn't to say insulin is bad by any means; we need it to preserve protein balance and maintain muscle mass, as well as for other critical bodily functions. We just don't need it elevated at certain times.
Conversely, cAMP can indeed be preserved by methylxanthines in coffee and tea, as they interfere with a cAMP destroyer called phosphodiesterase. So why aren't heavy coffee/tea drinkers all extremely lean? Because much of the fat that's broken down and mobilized circulates throughout the bloodstream of a sedentary person and eventually gets re-esterified or rebuilt into stored fat. It doesn't get taken up by contracting skeletal muscle and burned on its trip through the blood.
T-Nation: So mobilizing the fatty acids from adipose tissue isn't enough?
Dr. Lowery: No, moderate intensity exercise (muscle contractions to take up the circulating fatty acids) is necessary.
It should also be noted that exercise itself, particularly after fasting for a couple of hours, stimulates cAMP naturally by way of hormones such as epinephrine (adrenalin). This is a better long term approach to fat loss because excessive, ongoing coffee/caffeine intake can lead to higher cortisol concentrations over time, which ironically could worsen central body fat gain according to relatively new research. Not to mention cardiac arrhythmias (skipped beats), sleeplessness, anxiety, and the other classic side effects of excess caffeine.
Lastly, the intensity of the exercise bout affects whether fat or carbohydrate is used as a fuel source. This is the well-known crossover effect. Intense exercise is too rapid/demanding to allow for fat breakdown/oxidation. Carbohydrate (glycogen) must be used. Hence, fasting or drinking a cup of coffee prior to intense exercise isn't as helpful.
There's a school of thought that moderate, non-panting exercise in a mostly-fasted state can be done frequently and effectively for direct fat burning and subsequent body composition improvements. A cup of coffee or green tea would be helpful in such a situation biochemically, although there's no research to my knowledge directly investigating the all-important end result of better fat loss over time.
And there's an opposing and equally valid school of thought that more intense exercise also leads to leanness over time, as well as cardiovascular benefits. The choice becomes situation specific.
Now, when physique is paramount, I prefer fasted or mostly-fasted (half a scoop protein in water or coffee), non-panting AM cardio for 45-75 minutes that facilitates rather than harms recovery. (About 60% of VO2max keeps one below neuro-endocrine thresholds.)
It doesn't feel like a workout because it's not meant to be one. It doesn't add to training volume or risk overtraining and staleness, which, by the way, hits about half of individual sport athletes.
This approach also directly mobilizes and burns fat stores without draining biological resources toward cardiovascular adaptations. I don't want to be a runner. (Many bodybuilders don't care about much other than highly visible muscle mass.)
T-Nation: Holy crap, Lowery, leave something for the others to talk about! Okay, Barr, let's hear your opinion. Is fasted cardio good or bad?
David Barr: It's horrible! We should never be completely fasted for any reason. As soon as you're protein starved, you start breaking down muscle, which directly contradicts our goals, whether they be fat loss, muscle growth, or athletic performance.
Throw a catabolic activity like cardio on top of that and you're practically begging to waste away. Fortunately, it's not too difficult to prevent this muscle catabolism, because all we have to do is eat a little protein.
When it comes to cardio, eating protein before the session will preserve muscle tissue without impacting on fat loss. While some of the protein will be "burned off" as energy, the amount of muscle saved will more than make up for any minor alterations in fat calorie expenditure. Low-Carb Grow! is the perfect protein for this, because its slow entry into the blood limits the amount of amino acids that'll be used for energy (i.e. oxidized).
As for the other macronutrients, it's fine to be fasted as long as you're strictly going for fat loss. Understand that at first you'll feel the energy depravation, and may even want to prematurely cut your cardio short. If this occurs, then using something like Spike or especially HOT-ROX will not only enhance energy levels, but directly increase fat loss.
T-Nation: Thank you, you Biotest whore. What are your thoughts on morning cardio, Thib?
Christian Thibaudeau: Well, I'd first like to say that nothing is 100% good or bad. Morning cardio is no exception. When faced with such a subject, I always end up doing a pros and cons list and go from there. This way I can better organize my own opinion and give the readers a chance to make up their own minds.
First, let's look at the pros of fasted morning cardio:
Pro #1: Morning cardio could potentially increase the amount of free fatty acids (FFA) used up as fuel. This is not due to performing cardio in a glycogen depleted state though, since this isn't happening here. Unless you go to sleep in an already depleted state, you won't wake up in such a state.
During sleep almost 100% of the energy expended comes from fatty acids because of the extremely low intensity of the activity and because of the natural hGH burst which occurs 30 minutes or so after you enter the deep sleep phase (hGH increases fatty acid mobilization).
So you really aren't depleting your intramuscular glycogen stores during the night. You might be tapping your hepatic glycogen stores slightly, but even then that can't account for much since at best this contains maybe 200-300kcals of stored energy. So it's a fallacy to believe that when you wake up your muscles are emptied of their glycogen.
However, since fat is the primary energy source during your sleeping period, chances are that upon waking you have a greater amount of free fatty acids available. Since you don't have to mobilize them (they're already freed up) they become easier to oxidize for fuel and are thus more readily used up during morning cardio.
Pro #2: Fasted morning cardio could also potentially be glycogen-sparing for the same reason as stated above: the greater availability of FFAs reduces the reliance of glycogen for fuel during low-intensity energy systems work.
Pro #3: Fasted morning cardio could lead to an improved fatty acid mobilization during exercise and increase insulin sensitivity afterwards. This might be true of exercise at a low level of intensity (50-75% of max VO2) since this decreases insulin levels via the stimulation of adrenergic receptors. A lower insulin level can increase fatty acid mobilization.
However, a higher intensity of work (above 75% of max VO2) can actually have the opposite effect. So in that regard a moderate or even low intensity of work would seem to be superior in the morning as far as fat mobilization goes. (Galbo, 1983, Poortmans et Boiseau, 2003)
To counterbalance the reduction in insulin production during exercise at a moderate intensity, insulin sensitivity is increased, especially in the muscle. Since insulin sensitivity is already high in the fasted state, morning cardio could allow you to significantly increase glycogen storage and reduce the storage of carbohydrates as body fat.
So in that regard, morning cardio in a fasted state could increase fat loss during a cutting period and allow a bodybuilder in a bulking phase to significantly increase his carb intake without gaining more fat.
T-Nation: Okay, all that sounds good, so what are the cons?
Thibaudeau: If fasted state cardio could potentially increase fat mobilization, it's also potentially more catabolic to muscle tissue. This is due to an increase in cortisol production during fasted exercise. Since cortisol levels are already high in the morning, this could lead to more muscle wasting than during non-fasted cardio.
In fact, cortisol levels could increase muscle breakdown and the use of amino acids as an energy source. This is especially true if high-intensity energy systems work is performed. If an individual uses lower intensity (around 60-65% of maximum heart rate), the need for glucose and cortisol release are both reduced and thus the situation becomes less catabolic.
I personally do believe in the efficacy of morning cardio, but not in a completely fasted state. For optimal results I prefer to ingest a small amount of amino acids approximately 15-30 minutes before the cardio session. A mix of 5g of BCAA, 5g of glutamine (yeah, I know that Dave Barr won't agree with me on this!), and 5g of essential amino acids would do the trick in preventing any unwanted muscle breakdown.
However, I'll also play devil's advocate and say that morning cardio won't be drastically more effective than post-workout or afternoon cardio work when it comes to fat loss. Personally, I prefer to split up my cardio into two shorter sessions (morning and post-workout).
T-Nation: Interesting. Now let's hear what Berardi has to say.
Dr. John Berardi: Geez, is there much left to say? These guys hogged all the sciency sounding arguments so I'll just shoot straight and to the point.
I wish there were a simple "good or bad" answer to this question, but there isn't. Things are never this simple. After all, I believe that AM cardio performed on an empty stomach is incredibly awesome for fat loss in certain situations and should be avoided at all costs in others. How's that for an answer?
Here are the circumstances in which I think fasted cardio is awesome and in which I think fasted cardio isn't so awesome:
• AM fasted cardio should be done when you're only interested in body comp and you have either a mesomorphic or endomorphic body type.
• AM fasted cardio should never be done when you're an anaerobic athlete requiring strength and power or you simply have an ectomorphic (naturally skinny) body type.
To make it even simpler, here's a chart to determine if AM fasted cardio is for you:
Attachment:
chart.JPG [ 11.56 KiB | Viewed 30 times ]
Featuring Christian Thibaudeau, Dr. Lonnie Lowery, David Barr, and Dr. John Berardi
Moderated by Chris Shugart
It's a subject that always leads to a heated debate: cardio performed in the morning on an empty stomach. Is this the fastest way to lose fat, or is it a sure way to "eat up" all that hard-earned muscle? We sat down with four T-Nation experts and decided to find out.
T-Nation: Several years ago, fasted cardio was touted as being the quickest way to drop excess body fat. The general suggestion was to wake up, drink some water, then do your cardio before eating.
But then many experts started harping about muscle loss in this state. They said that fasted morning cardio was just too catabolic. So, fasted energy systems work: good or bad? Lead us off, Lonnie!
Dr. Lonnie Lowery: From a biological perspective, fasting for a few hours or overnight does result in much lower insulin concentrations in the blood. This facilitates fat oxidation because insulin, as a necessary storage hormone, indirectly degrades the secondary messenger "cyclic AMP" within adipocytes or fat cells.
Cyclic AMP is a signal to break things down within a cell such as glycogen (stored carbohydrate in muscle tissue) and yes, triacylglycerols (stored fat in muscle and fat tissue). So in weight loss situations, well-timed lower insulin concentrations can be helpful.
There are even data suggesting that its effects linger for many hours, making the first few waking hours an advantageous target. That is, we don't always want cAMP being degraded, and prior to breakfast it won't be. This isn't to say insulin is bad by any means; we need it to preserve protein balance and maintain muscle mass, as well as for other critical bodily functions. We just don't need it elevated at certain times.
Conversely, cAMP can indeed be preserved by methylxanthines in coffee and tea, as they interfere with a cAMP destroyer called phosphodiesterase. So why aren't heavy coffee/tea drinkers all extremely lean? Because much of the fat that's broken down and mobilized circulates throughout the bloodstream of a sedentary person and eventually gets re-esterified or rebuilt into stored fat. It doesn't get taken up by contracting skeletal muscle and burned on its trip through the blood.
T-Nation: So mobilizing the fatty acids from adipose tissue isn't enough?
Dr. Lowery: No, moderate intensity exercise (muscle contractions to take up the circulating fatty acids) is necessary.
It should also be noted that exercise itself, particularly after fasting for a couple of hours, stimulates cAMP naturally by way of hormones such as epinephrine (adrenalin). This is a better long term approach to fat loss because excessive, ongoing coffee/caffeine intake can lead to higher cortisol concentrations over time, which ironically could worsen central body fat gain according to relatively new research. Not to mention cardiac arrhythmias (skipped beats), sleeplessness, anxiety, and the other classic side effects of excess caffeine.
Lastly, the intensity of the exercise bout affects whether fat or carbohydrate is used as a fuel source. This is the well-known crossover effect. Intense exercise is too rapid/demanding to allow for fat breakdown/oxidation. Carbohydrate (glycogen) must be used. Hence, fasting or drinking a cup of coffee prior to intense exercise isn't as helpful.
There's a school of thought that moderate, non-panting exercise in a mostly-fasted state can be done frequently and effectively for direct fat burning and subsequent body composition improvements. A cup of coffee or green tea would be helpful in such a situation biochemically, although there's no research to my knowledge directly investigating the all-important end result of better fat loss over time.
And there's an opposing and equally valid school of thought that more intense exercise also leads to leanness over time, as well as cardiovascular benefits. The choice becomes situation specific.
Now, when physique is paramount, I prefer fasted or mostly-fasted (half a scoop protein in water or coffee), non-panting AM cardio for 45-75 minutes that facilitates rather than harms recovery. (About 60% of VO2max keeps one below neuro-endocrine thresholds.)
It doesn't feel like a workout because it's not meant to be one. It doesn't add to training volume or risk overtraining and staleness, which, by the way, hits about half of individual sport athletes.
This approach also directly mobilizes and burns fat stores without draining biological resources toward cardiovascular adaptations. I don't want to be a runner. (Many bodybuilders don't care about much other than highly visible muscle mass.)
T-Nation: Holy crap, Lowery, leave something for the others to talk about! Okay, Barr, let's hear your opinion. Is fasted cardio good or bad?
David Barr: It's horrible! We should never be completely fasted for any reason. As soon as you're protein starved, you start breaking down muscle, which directly contradicts our goals, whether they be fat loss, muscle growth, or athletic performance.
Throw a catabolic activity like cardio on top of that and you're practically begging to waste away. Fortunately, it's not too difficult to prevent this muscle catabolism, because all we have to do is eat a little protein.
When it comes to cardio, eating protein before the session will preserve muscle tissue without impacting on fat loss. While some of the protein will be "burned off" as energy, the amount of muscle saved will more than make up for any minor alterations in fat calorie expenditure. Low-Carb Grow! is the perfect protein for this, because its slow entry into the blood limits the amount of amino acids that'll be used for energy (i.e. oxidized).
As for the other macronutrients, it's fine to be fasted as long as you're strictly going for fat loss. Understand that at first you'll feel the energy depravation, and may even want to prematurely cut your cardio short. If this occurs, then using something like Spike or especially HOT-ROX will not only enhance energy levels, but directly increase fat loss.
T-Nation: Thank you, you Biotest whore. What are your thoughts on morning cardio, Thib?
Christian Thibaudeau: Well, I'd first like to say that nothing is 100% good or bad. Morning cardio is no exception. When faced with such a subject, I always end up doing a pros and cons list and go from there. This way I can better organize my own opinion and give the readers a chance to make up their own minds.
First, let's look at the pros of fasted morning cardio:
Pro #1: Morning cardio could potentially increase the amount of free fatty acids (FFA) used up as fuel. This is not due to performing cardio in a glycogen depleted state though, since this isn't happening here. Unless you go to sleep in an already depleted state, you won't wake up in such a state.
During sleep almost 100% of the energy expended comes from fatty acids because of the extremely low intensity of the activity and because of the natural hGH burst which occurs 30 minutes or so after you enter the deep sleep phase (hGH increases fatty acid mobilization).
So you really aren't depleting your intramuscular glycogen stores during the night. You might be tapping your hepatic glycogen stores slightly, but even then that can't account for much since at best this contains maybe 200-300kcals of stored energy. So it's a fallacy to believe that when you wake up your muscles are emptied of their glycogen.
However, since fat is the primary energy source during your sleeping period, chances are that upon waking you have a greater amount of free fatty acids available. Since you don't have to mobilize them (they're already freed up) they become easier to oxidize for fuel and are thus more readily used up during morning cardio.
Pro #2: Fasted morning cardio could also potentially be glycogen-sparing for the same reason as stated above: the greater availability of FFAs reduces the reliance of glycogen for fuel during low-intensity energy systems work.
Pro #3: Fasted morning cardio could lead to an improved fatty acid mobilization during exercise and increase insulin sensitivity afterwards. This might be true of exercise at a low level of intensity (50-75% of max VO2) since this decreases insulin levels via the stimulation of adrenergic receptors. A lower insulin level can increase fatty acid mobilization.
However, a higher intensity of work (above 75% of max VO2) can actually have the opposite effect. So in that regard a moderate or even low intensity of work would seem to be superior in the morning as far as fat mobilization goes. (Galbo, 1983, Poortmans et Boiseau, 2003)
To counterbalance the reduction in insulin production during exercise at a moderate intensity, insulin sensitivity is increased, especially in the muscle. Since insulin sensitivity is already high in the fasted state, morning cardio could allow you to significantly increase glycogen storage and reduce the storage of carbohydrates as body fat.
So in that regard, morning cardio in a fasted state could increase fat loss during a cutting period and allow a bodybuilder in a bulking phase to significantly increase his carb intake without gaining more fat.
T-Nation: Okay, all that sounds good, so what are the cons?
Thibaudeau: If fasted state cardio could potentially increase fat mobilization, it's also potentially more catabolic to muscle tissue. This is due to an increase in cortisol production during fasted exercise. Since cortisol levels are already high in the morning, this could lead to more muscle wasting than during non-fasted cardio.
In fact, cortisol levels could increase muscle breakdown and the use of amino acids as an energy source. This is especially true if high-intensity energy systems work is performed. If an individual uses lower intensity (around 60-65% of maximum heart rate), the need for glucose and cortisol release are both reduced and thus the situation becomes less catabolic.
I personally do believe in the efficacy of morning cardio, but not in a completely fasted state. For optimal results I prefer to ingest a small amount of amino acids approximately 15-30 minutes before the cardio session. A mix of 5g of BCAA, 5g of glutamine (yeah, I know that Dave Barr won't agree with me on this!), and 5g of essential amino acids would do the trick in preventing any unwanted muscle breakdown.
However, I'll also play devil's advocate and say that morning cardio won't be drastically more effective than post-workout or afternoon cardio work when it comes to fat loss. Personally, I prefer to split up my cardio into two shorter sessions (morning and post-workout).
T-Nation: Interesting. Now let's hear what Berardi has to say.
Dr. John Berardi: Geez, is there much left to say? These guys hogged all the sciency sounding arguments so I'll just shoot straight and to the point.
I wish there were a simple "good or bad" answer to this question, but there isn't. Things are never this simple. After all, I believe that AM cardio performed on an empty stomach is incredibly awesome for fat loss in certain situations and should be avoided at all costs in others. How's that for an answer?
Here are the circumstances in which I think fasted cardio is awesome and in which I think fasted cardio isn't so awesome:
• AM fasted cardio should be done when you're only interested in body comp and you have either a mesomorphic or endomorphic body type.
• AM fasted cardio should never be done when you're an anaerobic athlete requiring strength and power or you simply have an ectomorphic (naturally skinny) body type.
To make it even simpler, here's a chart to determine if AM fasted cardio is for you:
Attachment:
chart.JPG [ 11.56 KiB | Viewed 30 times ]