Yet ANOTHER Study Debunking "fasted cardio"
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I just want to say thank you for this. I got a good chuckle out of it this morning.Foamroller wrote: »
As I said. I don't care about statistical significance. I only care about the actual numbers
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I prefer to do my workouts in the morning before I eat. I get better results.
Ditto.
Like Mr Knight, I'll actually do my workouts first thing in the morning... later in the day, not so regularly. Consistency = results.
It's not possible for me to keep food (or liquid) down if I eat too soon after waking. I can't even imagine how my stomach would fare if I ate before working out
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Like with all studies I wish the sample size was larger, the duration was longer, the calorie intake was not self reported, the subjects were my exact height, weight, age, fitness level....
This study is another useful bit of information, even with its limitations. Maybe the fat loss results would start to show a difference over a longer period of time but so might FFM loss. NOT MY GAINS!
Performance, adherence, recovery and probably some other things would not be measured in any case but are just as important when considering things like this.
I think "personal preference" is still the correct answer for fasted vs fed cardio. I have not seen one study that show any significant advantage but have not seen one showing anything bad about it either.
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mustgetmuscles1 wrote: »I have not seen one study that show any significant advantage but have not seen one showing anything bad about it either.
Well, one downside is it could make your breath smell. I can often tell when someone at my gym is in a fasted state, because of the stank. It seems that some people can't smell it though. Presumably the smell is from muscle being burned as fuel.. which doesn't seem to be an optimal state to be in.
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Foamroller wrote: »
Anyway, I would say that if the scientist who made this study was after statistical significance, then why was the study comprised of only 20 participants, effectively making the numbers in each group consisting only of 10 individuals. It's also a bit concerning that although the participants were randomized. ALL the younger females were clumped into the fed group. Could a more spread population perhaps have differed the results? I don't know.
Could the fact that all the participants were not very fat, probably very athletic also give different results compared to, let's say BMI above 28 people.
Since you are so much more scholarly endowed than me, I'm sure you would know that a "study" of 20 people is NOT a big enough number to make conclusions about the GENERAL POPULATION. So based on that the whole study is not statistically significant whichever conclusion you want to believe is right.
Actually that weird clumping makes it look more like it was a truly randomised study. Despite what common sense tells us, you expect clumps in random samples.0 -
redfiona99 wrote: »Foamroller wrote: »
Anyway, I would say that if the scientist who made this study was after statistical significance, then why was the study comprised of only 20 participants, effectively making the numbers in each group consisting only of 10 individuals. It's also a bit concerning that although the participants were randomized. ALL the younger females were clumped into the fed group. Could a more spread population perhaps have differed the results? I don't know.
Could the fact that all the participants were not very fat, probably very athletic also give different results compared to, let's say BMI above 28 people.
Since you are so much more scholarly endowed than me, I'm sure you would know that a "study" of 20 people is NOT a big enough number to make conclusions about the GENERAL POPULATION. So based on that the whole study is not statistically significant whichever conclusion you want to believe is right.
Actually that weird clumping makes it look more like it was a truly randomised study. Despite what common sense tells us, you expect clumps in random samples.
Yup, you expect a lot of things with random samples, including random people being unable to understand why a study has a certain size, or that groups were done in a certain way.0 -
The study proves nothing based on the small demo of participants and the short duration. Plus, just based on the statistical significance, it would be impossible to get any real data because not matter what, the numbers would always be too close to call.
Personally, I do my morning runs fasted because, if I eat before running, I get gastro issues. I also do my strength training fasted for no real reason other than I don't want to eat at 5:30 AM. I'd rather eat after my workout at 7 AM.
Science never proves anything. It simply provides evidence for or against a hypothesis. The law of gravity is never "proven" true....it just hasn't ever been shown to be false in any study. No matter the scale, if the evidence is there, then the statement can be made. The law of averages come into play, of course, so if the sample size is small, and it is a single study, it cannot scientifically represent the whole group (a whole population).
Significance is also subjective. 0.1 lbs to a 400 lb person is not the same as it is to a 150 lb person. Same with the data in this study. When measuring body fat composition, it could be argued that 0.01% is significant considering the length of time it takes to lose overall body fat.
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Given the time and effort involved in doing any study such as this, sample sizes are always going to be small. Within the context of this type of research, the sample size is acceptable--usually it has to be if the study is going to be accepted for publication (peer review and all).Foamroller wrote: »I'd say using a word like "DEBUNKED" is jumping the gun. You forgot to mention that the study consisted of 20 women. ...Although peer reviewed, that's a very scant sample to generalized conclusion up to a general population.
Any study has to control for variables and one must always exercise caution when generalizing results to the general population (as one must always exercise caution and restraint trying to microparse a study to cast it in a negative light because the results challenge a strongly-held dogma).
While this study is somewhat unique in that (per the authors) it is the first to look at actual effects of fasted vs non-fasted (as opposed to extrapolating results from an acute response), it is hardly groundbreaking. It mostly confirmed what exercise researchers already know.Burning fat cells only starts after 20 minutes of continuous exercise. I really wonder how that significant "fat loss" could occur. I've been taught that the total kcal burn is higher at higher intensity, and thereby also the fat burn. I tested it myself in 10 minute intervals. I burn 45 kcal at 70%, 55 kcal at 75% and a whopping 80 kcal at 80% almost doubling the burn. (the burns are low cause I'm old and not overweight anymore)
See my earlier remarks about extrapolating (wrongly) from acute responses. Substrate utilization during exercise has no effect on fat loss. The amount of fat burned during an exercise session is trivial to begin with and the difference between "fasted" and "non-fasted" is no more than about 1/2 oz after a 60 min workout. And, even that tiny difference is wiped out because the body up and down regulates fat oxidation over the following hours, so that at the end of the day, total fat oxidation is equal.
(Exerc Sport Sci Rev. 2009 April ; 37(2): 93–101.
Exercise improves fat metabolism in muscle but does not increase 24-h fat oxidation
Edward L Melanson, Ph.D., Paul S. MacLean, Ph.D., and James O. Hill, Ph.D.)
Your point about intensity vs calories is irrelevant in that it has nothing to do with fasted vs unfasted exercise.
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IMO, if they were going to do a study on this with more accuracy, they should use twins who are are the same weight and body fat percentage.
A.C.E. Certified Personal and Group Fitness Trainer
IDEA Fitness member
Kickboxing Certified Instructor
Been in fitness for 30 years and have studied kinesiology and nutrition
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i don't eat or drink before i run just because it makes me feel sick. not sure why anyone would think when you consume your calories will make a difference to fat loss. it's still going to come back to in vs. out.0
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From the study it seems that caloric deficit is far more important that doing cardio while fasted. I would like to see a longer term study to verify this, but 4 weeks is enough to make a good case for the difference being small enough to not be something to consider in the big picture.0
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IMO, if they were going to do a study on this with more accuracy, they should use twins who are are the same weight and body fat percentage.
A.C.E. Certified Personal and Group Fitness Trainer
IDEA Fitness member
Kickboxing Certified Instructor
Been in fitness for 30 years and have studied kinesiology and nutrition
Ha! good luck finding that here in America! And all the Swedes' twins are taken: they are doing behavioral, developmental, and genetics studies on them.
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Honestly, if you get it done at all, that seems like quite enough to me. Go with your individual preference regarding food, whatever, seriously.0
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Honestly, if you get it done at all, that seems like quite enough to me. Go with your individual preference regarding food, whatever, seriously.
Nice contribution to the conversation. I think that has to be the most generic and basic staple of thought here on the forums. You can pretty much just say that on any thread, because, why study anything? "Get it done....nothing else matters, maaaan! You don't need to get smarter. That's for dummies!"
I jest...-1 -
If people want to fast for 24 hours and then workout or eat while they run, it makes absolutely no difference to me.
Everyone should do what works for them!0 -
I agree it's pretty much confirming what we already know, or thought. I remember when Body for Life came out and Phillips' claims about fasted exercise were so wrong-- he almost said "if you can't do it fasted, don't even bother"-- and Phillips did later retract that and admit it was based on misunderstanding the science.
Given the time and effort involved in doing any study such as this, sample sizes are always going to be small. Within the context of this type of research, the sample size is acceptable--usually it has to be if the study is going to be accepted for publication (peer review and all).Foamroller wrote: »I'd say using a word like "DEBUNKED" is jumping the gun. You forgot to mention that the study consisted of 20 women. ...Although peer reviewed, that's a very scant sample to generalized conclusion up to a general population.
Any study has to control for variables and one must always exercise caution when generalizing results to the general population (as one must always exercise caution and restraint trying to microparse a study to cast it in a negative light because the results challenge a strongly-held dogma).
While this study is somewhat unique in that (per the authors) it is the first to look at actual effects of fasted vs non-fasted (as opposed to extrapolating results from an acute response), it is hardly groundbreaking. It mostly confirmed what exercise researchers already know.
I also agree that small samples are usually acceptable. It's a foundation of statistics. That's why we see the significance factors in all the studies. It's possible that 20 college students react significantly differently in this circumstance than most adults, but it's very unlikely. If we couldn't learn from samples, there would be very little science. If *this* sample was too small to gain knowledge from, the study wouldn't pass peer review and be published.
Totally as an aside-- Note that the 20 subjects ate under 1300/day for the 4 weeks and neither wasted away nor failed to complete their hour long workouts.
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WalkingAlong wrote: »
Given the time and effort involved in doing any study such as this, sample sizes are always going to be small. Within the context of this type of research, the sample size is acceptable--usually it has to be if the study is going to be accepted for publication (peer review and all).Foamroller wrote: »I'd say using a word like "DEBUNKED" is jumping the gun. You forgot to mention that the study consisted of 20 women. ...Although peer reviewed, that's a very scant sample to generalized conclusion up to a general population.
Any study has to control for variables and one must always exercise caution when generalizing results to the general population (as one must always exercise caution and restraint trying to microparse a study to cast it in a negative light because the results challenge a strongly-held dogma).
While this study is somewhat unique in that (per the authors) it is the first to look at actual effects of fasted vs non-fasted (as opposed to extrapolating results from an acute response), it is hardly groundbreaking. It mostly confirmed what exercise researchers already know.
Totally as an aside-- Note that the 20 subjects ate under 1300/day for the 4 weeks and neither wasted away nor failed to complete their hour long workouts.
Nice catch. Some of the most valuable info I get from studies comes from that "secondary" reading of the data.
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Translation: Ignorance is blissFoamroller wrote: »
I know the meaning of statistical significance. Now you remind me of why I'm very happy I never pursued an academic carrier.FunkyTobias wrote: »Foamroller wrote: »FunkyTobias wrote: »Foamroller wrote: »I don't care if that is statistically insignificant. I'll take a 0.6% extra bodyfat loss for fasted cardio any day, ha-ha.
Then you clearly don't understand statistical significance. 0.6% is far below the accuracy of ANY bodyfat measuring technique (except perhaps vivisection).
As I said. I don't care about statistical significance. I only care about the actual numbers
Derp.
Lack of statistical significance means that the difference in the results is no different than you would expect from random chance. If, instead of fasted/fed, they plotted the results by the color of their outfits, you find a similar result.Anyway, I would say that if the scientist who made this study was after statistical significance, then why was the study comprised of only 20 participants, effectively making the numbers in each group consisting only of 10 individuals.
You say you understand "statistical significance" then you proceed to conflate it with "effect size". Please take a course in fundamental statistics before spewing more crap.It's also a bit concerning that although the participants were randomized. ALL the younger females were clumped into the fed group. Could a more spread population perhaps have differed the results? I don't know.
And now you show you don't understand randomization either.Could the fact that all the participants were not very fat, probably very athletic also give different results compared to, let's say BMI above 28 people.
Very different. The proposed mechanism of action for fasted cardio has always been fat mobilization, which has never been an issue for anyone but the already lean trying to get even leaner.Since you are so much more scholarly endowed than me, I'm sure you would know that a "study" of 20 people is NOT a big enough number to make conclusions about the GENERAL POPULATION. So based on that the whole study is not statistically significant whichever conclusion you want to believe is right.
Once again you show that you don't understand how any of this works.
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I just died laughing.
Thanks, now my wife gets to turn in my life insurance.0 -
I do my best running fasted, for the simple reason that's the only way my stomach doesn't get upset. I didn't even know it was a 'fat burning' thing.
Fasted exercise = actually being able to run
non fasted exercise = throwing up at the side of the road.
But the amount of people who have told me that I'm doing it wrong is astonishing, that my performance would be better, that I'm just eating the wrong foods, I'm going to lose all muscle mass blah blah.
If it's between 90% performance and a nauseous half a mile and then vomiting on my shoes, I know what I'd prefer.0 -
JenniDaisy wrote: »I do my best running fasted, for the simple reason that's the only way my stomach doesn't get upset. I didn't even know it was a 'fat burning' thing.
Fasted exercise = actually being able to run
non fasted exercise = throwing up at the side of the road.
But the amount of people who have told me that I'm doing it wrong is astonishing, that my performance would be better, that I'm just eating the wrong foods, I'm going to lose all muscle mass blah blah.
If it's between 90% performance and a nauseous half a mile and then vomiting on my shoes, I know what I'd prefer.
People have a tendency to vastly underestimate the amount of stored fuel we have-even in a "fasted" state--and overestimate the quality of their workouts.0 -
JenniDaisy wrote: »I do my best running fasted, for the simple reason that's the only way my stomach doesn't get upset. I didn't even know it was a 'fat burning' thing.
Fasted exercise = actually being able to run
non fasted exercise = throwing up at the side of the road.
But the amount of people who have told me that I'm doing it wrong is astonishing, that my performance would be better, that I'm just eating the wrong foods, I'm going to lose all muscle mass blah blah.
If it's between 90% performance and a nauseous half a mile and then vomiting on my shoes, I know what I'd prefer.
People have a tendency to vastly underestimate the amount of stored fuel we have-even in a "fasted" state--and overestimate the quality of their workouts.
Truth!
I also prefer exercising fasted, not because I think it will result in greater fat loss, but because I simply prefer it. I don't notice a performance decrease, so I do what I prefer. If I did notice I performed better fed, I would eat first simple as that.
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I suppose it also depends where the notion that fasted cardio increases fat burning is derived. I thought this came from advice to people on keto or slow carb diet that fasted cardio increased the speed at which you could return to keto following a refeed. I think this is because the fasted cardio depletes liver glycogen. If this the case then I could see that fasted cardio would increase the amount of time spent in ketosis and therefore improve the proportion of fat lost versus lbm...but only relevant to keto dieters.0
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Hello everyone, I'm one the study authors. First off, thanks for your interest in this stuff. We spent many months grinding this baby out, and it's great to see it unleashed into the public, spawning discussions like this one. I see that there are some highly knowledgable folks in this thread regarding research methodology - I suggest you listen to them rather than wrestle with them. There's no such thing as research devoid of limitations, and if you read the text, we explicitly discuss the limitations of our work.
You'll notice that there's a disparity between the reported caloric totals and the degree of weight loss - this is undoubtedly due to under-reported intake. But note that under-reporting to a substantial degree is a common occurrence in diet research; it comes with the territory.
Last but not least, an important point I want to make that often eludes folks is that our study (like any study) is merely a piece of the larger puzzle. No single study is capable of defining or "owning" the entire body of evidence. It merely adds to it, nudging the weight of the evidence in one way or the other. The current body of evidence - both acute & chronic data - does not lean compellingly in favor or either fed or fasted cardio for weight/fat loss. To end off, I'll reiterate what I've posted elsewhere:
______________________________________
If I were to plunk down a practical application for the audience here, it would be that for the goal of fat loss, a net caloric deficit sustained over a period of weeks or months is what matters, not the micromanagement of the placement of your first meal relative to cardio (if you happen to do cardio at all). As seen in our work, fed or fasted moderate-intensity cardio can be done according to individual preference since one doesn't appear to have a meaningful advantage over the other. On a side-note, some people get very uncomfortable at the idea that there's flexibility of the smaller details within a larger framework. "Just tell me which way is better, either fed or fasted HAS to be better, right?" Nope, some things matter, some things might actually not matter, so personal preference should take precedence in the latter.0 -
Thanks for dropping by Alan....long time fan, over a decade and counting. Basically daily CICO dominate and trying to manipulate the minutia is basically trying to swim upstream. I'm also in the camp that believes that adherence (preference) is king.AlanAragon wrote: »Hello everyone, I'm one the study authors. First off, thanks for your interest in this stuff. We spent many months grinding this baby out, and it's great to see it unleashed into the public, spawning discussions like this one. I see that there are some highly knowledgable folks in this thread regarding research methodology - I suggest you listen to them rather than wrestle with them. There's no such thing as research devoid of limitations, and if you read the text, we explicitly discuss the limitations of our work.
You'll notice that there's a disparity between the reported caloric totals and the degree of weight loss - this is undoubtedly due to under-reported intake. But note that under-reporting to a substantial degree is a common occurrence in diet research; it comes with the territory.
Last but not least, an important point I want to make that often eludes folks is that our study (like any study) is merely a piece of the larger puzzle. No single study is capable of defining or "owning" the entire body of evidence. It merely adds to it, nudging the weight of the evidence in one way or the other. The current body of evidence - both acute & chronic data - does not lean compellingly in favor or either fed or fasted cardio for weight/fat loss. To end off, I'll reiterate what I've posted elsewhere:
______________________________________
If I were to plunk down a practical application for the audience here, it would be that for the goal of fat loss, a net caloric deficit sustained over a period of weeks or months is what matters, not the micromanagement of the placement of your first meal relative to cardio (if you happen to do cardio at all). As seen in our work, fed or fasted moderate-intensity cardio can be done according to individual preference since one doesn't appear to have a meaningful advantage over the other. On a side-note, some people get very uncomfortable at the idea that there's flexibility of the smaller details within a larger framework. "Just tell me which way is better, either fed or fasted HAS to be better, right?" Nope, some things matter, some things might actually not matter, so personal preference should take precedence in the latter.
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AlanAragon wrote: »Hello everyone, I'm one the study authors. First off, thanks for your interest in this stuff. We spent many months grinding this baby out, and it's great to see it unleashed into the public, spawning discussions like this one. I see that there are some highly knowledgable folks in this thread regarding research methodology - I suggest you listen to them rather than wrestle with them. There's no such thing as research devoid of limitations, and if you read the text, we explicitly discuss the limitations of our work.
You'll notice that there's a disparity between the reported caloric totals and the degree of weight loss - this is undoubtedly due to under-reported intake. But note that under-reporting to a substantial degree is a common occurrence in diet research; it comes with the territory.
Last but not least, an important point I want to make that often eludes folks is that our study (like any study) is merely a piece of the larger puzzle. No single study is capable of defining or "owning" the entire body of evidence. It merely adds to it, nudging the weight of the evidence in one way or the other. The current body of evidence - both acute & chronic data - does not lean compellingly in favor or either fed or fasted cardio for weight/fat loss. To end off, I'll reiterate what I've posted elsewhere:
______________________________________
If I were to plunk down a practical application for the audience here, it would be that for the goal of fat loss, a net caloric deficit sustained over a period of weeks or months is what matters, not the micromanagement of the placement of your first meal relative to cardio (if you happen to do cardio at all). As seen in our work, fed or fasted moderate-intensity cardio can be done according to individual preference since one doesn't appear to have a meaningful advantage over the other. On a side-note, some people get very uncomfortable at the idea that there's flexibility of the smaller details within a larger framework. "Just tell me which way is better, either fed or fasted HAS to be better, right?" Nope, some things matter, some things might actually not matter, so personal preference should take precedence in the latter.
Law of Averages: it provides that unless you have an enormous patient field in the end, including variation in sex, gender, body types, ages, and physical ability, or was able to perform a meta-analysis, it CANNOT be counted as a result for the entire said population. I am performing an n=1 experiment about a ketogenic diet on myself, but I will never say that "this diet is for you." I am simply providing the evidence that I physically have so that another can decide what is best for them, if they wish to try the ketogenic diet, or wish to replicate the experiment to find out the results for themselves. My body is vastly different than anyone else's, so I will never proclaim (from here on out- I have dim-wittingly done so in the past) that this diet or that method is best.
Just my input though....I am on a ketogenic diet and I do run fasted all the time. I have a tough stomach, so I don't throw up that often, but I have only thrown up from a workout when I am doing HIIT and have eaten foods that are made up of carbs.
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So in....,,,0
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AlanAragon wrote: »Hello everyone, I'm one the study authors. First off, thanks for your interest in this stuff. We spent many months grinding this baby out, and it's great to see it unleashed into the public, spawning discussions like this one. I see that there are some highly knowledgable folks in this thread regarding research methodology - I suggest you listen to them rather than wrestle with them. There's no such thing as research devoid of limitations, and if you read the text, we explicitly discuss the limitations of our work.
You'll notice that there's a disparity between the reported caloric totals and the degree of weight loss - this is undoubtedly due to under-reported intake. But note that under-reporting to a substantial degree is a common occurrence in diet research; it comes with the territory.
Last but not least, an important point I want to make that often eludes folks is that our study (like any study) is merely a piece of the larger puzzle. No single study is capable of defining or "owning" the entire body of evidence. It merely adds to it, nudging the weight of the evidence in one way or the other. The current body of evidence - both acute & chronic data - does not lean compellingly in favor or either fed or fasted cardio for weight/fat loss. To end off, I'll reiterate what I've posted elsewhere:
______________________________________
If I were to plunk down a practical application for the audience here, it would be that for the goal of fat loss, a net caloric deficit sustained over a period of weeks or months is what matters, not the micromanagement of the placement of your first meal relative to cardio (if you happen to do cardio at all). As seen in our work, fed or fasted moderate-intensity cardio can be done according to individual preference since one doesn't appear to have a meaningful advantage over the other. On a side-note, some people get very uncomfortable at the idea that there's flexibility of the smaller details within a larger framework. "Just tell me which way is better, either fed or fasted HAS to be better, right?" Nope, some things matter, some things might actually not matter, so personal preference should take precedence in the latter.
You should hang out here more often.
But don't invite Fred...
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