Yet ANOTHER Study Debunking "fasted cardio"

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.

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.

FrenchMob wrote: »

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.

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.

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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.

Honestly, if you get it done at all, that seems like quite enough to me. Go with your individual preference regarding food, whatever, seriously.

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!

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.

Azdak wrote: »

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.

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.

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.

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.












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