fasted exercise

[BT_707]

That was a very interesting podcast.

Honestly, I think some of this stuff is mental. I think anything that helps you stay consistent will be most effective.

If fasted cardio gives you the mental boost, I say do it. I respond best to hard and fast rules. If my rule is I don't eat till 1, and that I MUST do fasted cardio, its a good way to ensure my workout gets done.

All of his content is awesome. Dr’s. Galpin and Attia are also great.

 

[Mtnmilsurp]

fasted exercise doesn’t really activate fat burning, you’re still burning your huge stores of muscle glycogen and blood glucose first

…and your body’s going to replace that muscle/blood sugar with broken down fat if you’re fasted and don’t have sugar coming from recently eaten food. The body doesn’t burn fat as fat. It only burns fat by first breaking it down into sugar but it won’t do that if you’re putting sugar straight into your bloodstream by what/when you eat. If you train your body to replenish the ready supply (blood/muscle sugar) from fat stores while exercising you can sustain a much higher effort level for much longer (I mean hours) without hitting the wall. But, no doubt, the only stuff that gets thrown directly on the fire is the simple sugars. The question is how to keep them topped up—with food or stored fat.

 

[Marbles]

…and your body’s going to replace that muscle/blood sugar with broken down fat if you’re fasted and don’t have sugar coming from recently eaten food. The body doesn’t burn fat as fat. It only burns fat by first breaking it down into sugar but it won’t do that if you’re putting sugar straight into your bloodstream by what/when you eat. If you train your body to replenish the ready supply (blood/muscle sugar) from fat stores while exercising you can sustain a much higher effort level for much longer (I mean hours) without hitting the wall. But, no doubt, the only stuff that gets thrown directly on the fire is the simple sugars. The question is how to keep them topped up—with food or stored fat.

Muscle can burn ketone bodies. Gluconeogenesis from fat is to fuel the few tissues that cannot burn ketones.

If engaged in long course endurance starting fasted will likely result in depleting glycogen stores sooner, especially if it has been a moderately long fast as they will already have been partly consumed. In the end, it still comes down to replacing fewer calories than one burns to loose weight. Otherwise, even if one is burning fat stores for fuel, the body just replenishes the fat stores as the calories become available.

 

[V2Pnutrition]

To silo nutrition into this approach or that approach being the ultimate fix or “best” for performance (to speak to the OP’s original post) is missing the forest from the trees.

For example:

• Good economy of energy production (ATP) depends on vitamin intake- most of which are predominantly in grains and vegetables (which would nullify the carnivore approach as universally “best”).
• The higher the carb intake, the greater the preservation of the muscle for long-distance mountain events. (Which would mean fasted cardio isn’t the best approach- at least for people wanting to retain or build muscle-I.e. every red-blooded human on the planet).
• If training low-carb and then going to high carb for an event (as suggested in UA with the OP original comments), you have impaired utilization of carb when you DO go to use it (vs the guy who trained with it).
• 90g of carbs per hour for high outputs (as ‘recommended’ by summaries from the ISSN and based on data) would cause significant problems in the gut (even with optimal performance) for someone who hasn’t trained with it. Not to mention what it would do to the blood sugar of a sedentary individual.

The best thing about the world of nutrition is the ever-changing process of finding what works best for you. The goose and gander metaphor isn’t applicable. True, there are a few “absolutes”. Outside of that, it’s exploring what works best for you and what you want out of training, life, and performance.

We did a podcast on nutrient timing and what matters from a muscle preservation/performance standpoint. It’s linked here if you’re interested in checking out the science.

@Marbles hit the nail on the head if you’re looking at different approaches for weight loss- create a deficit. Period.

Side note to the OP @mtwarden excellent job on your midlayer review.

 

[P Carter]

To silo nutrition into this approach or that approach being the ultimate fix or “best” for performance (to speak to the OP’s original post) is missing the forest from the trees.

For example:

• Good economy of energy production (ATP) depends on vitamin intake- most of which are predominantly in grains and vegetables (which would nullify the carnivore approach as universally “best”).
• The higher the carb intake, the greater the preservation of the muscle for long-distance mountain events. (Which would mean fasted cardio isn’t the best approach- at least for people wanting to retain or build muscle-I.e. every red-blooded human on the planet).
• If training low-carb and then going to high carb for an event (as suggested in UA with the OP original comments), you have impaired utilization of carb when you DO go to use it (vs the guy who trained with it).
• 90g of carbs per hour for high outputs (as ‘recommended’ by summaries from the ISSN and based on data) would cause significant problems in the gut (even with optimal performance) for someone who hasn’t trained with it. Not to mention what it would do to the blood sugar of a sedentary individual.

The best thing about the world of nutrition is the ever-changing process of finding what works best for you. The goose and gander metaphor isn’t applicable. True, there are a few “absolutes”. Outside of that, it’s exploring what works best for you and what you want out of training, life, and performance.

We did a podcast on nutrient timing and what matters from a muscle preservation/performance standpoint. It’s linked here if you’re interested in checking out the science.

@Marbles hit the nail on the head if you’re looking at different approaches for weight loss- create a deficit. Period.

Side note to the OP @mtwarden excellent job on your midlayer review.

Just real quick, would you agree with the following assertions? (This is how I understand “fasted cardio”; not interested in another forum debate but I am interested in the topic.)

-since the aerobic pathway is the most important pathway for endurance activities, one should develop the aerobic pathway through activities that stress the aerobic pathway “from below” to raise the level of intensity at which your body uses the aerobic pathway versus anaerobic pathway, usually long slow distance. (This assumes the goal is to train optimally for an endurance activity, I completely agree that strength training is important even for endurance activities.)

-the aerobic pathway uses fat for fuel. So fasted aerobic training can assist in developing the aerobic pathway insofar as the body can deplete existing glycogen supplied more quickly and “get to” using fat as fuel more quickly

- but, performance is degraded in a fasted state since the ideal “fuel mix” would be partly from carb intake and partly from fat. In other words, if you train too much in a fasted stated you can’t go as far or as fast, so your performance will be unnecessarily capped.

-And if you’re training for an ultra event, you’ll need to train your gut for carb intake during the evebt

-fasted cardio has nothing to do with weight loss or altering your “on the body” mix of lean mass versus fat…At most it’d be to train one energy system (aerobic) over another (anaerobic). “Burning fat” sounds like a diet add and people take it as something to do with a “diet” or “losing fat” rather than training one energy pathway over another.

-at the end of the day, there’s no magic tricks. Volume is the key driver of aerobic development. So the ideal mix of fasted to non-fasted training a) doesn’t really matter to the non-elite athlete and b) I’d be better off to be training right now rather than posting about topics that would at most result in minimal improvements even if you got it 100% right, if there even is a 100% right in the context.

 

[mtwarden]

• If training low-carb and then going to high carb for an event (as suggested in UA with the OP original comments), you have impaired utilization of carb when you DO go to use it (vs the guy who trained with it).

UA advocates some training in a fasted state, but certainly not all- typically no more than two hours and always in Zone 1 or 2.

If training for longer events, which I think would definitely include hunters- then you need to train beyond two hours and should be ingesting calories as you go (predominately carbs, but likely some mix).

this was pointed out earlier in the thread and might be true; and if true, it might not matter a tinkers damn

Given your level of aerobic base, it wouldn’t surprise me at all if you didn’t notice a difference. I’d bet you’re a butter burner already; if you’re primarily running on the aerobic system, and your aerobic base is big enough, I think you primarily use fat as fuel even if you have glycogen available.

I can't say that I noticed any difference with morning fasted exercise, it certainly didn't hurt my aerobic capacity- that I'm certain. Improved- possibly? With the switch of the seasons, I've been getting my training in later (it's warmer ) so no fasted exercise. When "summer" rolls around and I'm training earlier to beat the heat, I likely go back to fasted again, if for no other reason than it's easier to just get up and go.

Side note to the OP @mtwarden excellent job on your midlayer review.

Thanks!

 

[P Carter]

I can't say that I noticed any difference with morning fasted exercise, it certainly didn't hurt my aerobic capacity- that I'm certain. Improved- possibly? With the switch of the seasons, I've been getting my training in later (it's warmer ) so no fasted exercise. When "summer" rolls around and I'm training earlier to beat the heat, I likely go back to fasted again, if for no other reason then it's easier to just get up and go.

I would imagine this is the most important part! Just get up and go is the 90%, tinkering on fasted versus non-fasted might have limited impact on the 10%.

 

[*zap*]

almost daily fasted liss worked very well for me both for fat loss and the ability to just keep moving/working. after 45 minutes I would have a small cliff bar/sit for 5 and I never did many sessions for more than 90 minutes. that was over the course of a year so as far as I am concerned the results were there for both things..

If you do not have nutrients in the bloodstream from having eaten and keep the heart rate low then you will have minimal insulin/glucose to fuel atp production. Thus you will burn fat. I am no expert but that sure makes sense to me..

I have known older folks with boundless energy who never exercise but just walk daily at a normal pace and keep moving thorough the day...all the women I see group walking every day are all slim. Not sure they walk fasted thou.

I think the best base exercise for anyone is walking, swimming or biking at slower pace for 45-90 minutes a day. Add a good strength program/stretching program and you should be golden. Sauna 3-4 hr. a week is also good.

I would do strength fed thou...and eat a bit right after.

 

[Marbles]

If you do not have nutrients in the bloodstream from having eaten and keep the heart rate low then you will have minimal insulin/glucose to fuel atp production. Thus you will burn fat. I am no expert but that sure makes sense to me..

This is really just discussion for the sake of discussion.

Insulin is a storage hormone, it triggers storage of fat, sugar, and creation of protein. I would bet (but human data is not available) that insulin is very low during exercise, and glucagon, epi, and other catabolic hormones are at work to fuel exercise.

 

[*zap*]

Wiki:
Low insulin levels in the blood have the opposite effect by promoting widespread catabolism, especially of reserve body fat.

So, I believe that insulin levels are low when you do not eat for 14 hours...but maybe not. If they are they low then that would promote using reserve body fat. Which is why some people say that to get rid of the hard to loose gender specific fat you will have good results by doing liss in a fasted state. That would align with my personal experience over a 14 month period.

 

[Marbles]

Well, it is too early to be certain, but I decided to start tracking when my runs are fasted vs feed. I did a long run today, eat breakfast before going on it, and started eating snacks after the half way mark and before I felt spent. So far, if I eat after feeding spent, it doesn't feel like it makes and difference, however this time I felt a lot stronger for the rest of the run.

There are several confounding factors.
1. My fasted long runs so far this year were in nasty conditions (snow, ices, wind) and this was a beautiful spring day.
2. Today's run was the longest one so far this year and I really wanted to bail on going the full distance at the start, the half way point is powerful psychologically as I'm stuck either finishing the run or calling my wife to come pick me up.
3. I cheated before this run and took ibuprofen and Tylenol because I new it was going to suck.
4. Part of my snack was a 8.4 ounce RedBull, though technically that only has enough caffeine to be a placebo athletically.

I plan to keep watching and see if I can identify a clear trend regarding pace between fasted and fed (objective data) and how I feel at the end of the run (subjective data). Fasted means a run where I have not consumed calories for at least 10 hours prior to running.

 

[Marbles]

Well, I did a fasted threshold run today. 20 minutes very easy warm up, followed by a 51 minute hard pace, followed by a 25 minute cool down.

My average HR for the 51 minute threshold portion was 185 bpm, I set a personal best 10 k time, and I felt good after it. I also did not have any noticable decoupling of pace and HR, even the a headwind for the second half. I was fasted for at least 12 hour prior, though I did have 2 cups of black coffee prior to heading out. It felt better than the 6k run I did Wednesday which was not fasted. I did stuff my face when I got back though.

This, in combination with the studies on ulta endurance athletes makes me inclined to put the conventional wisdom of "needing" to fuel during activity in the realm of dogma. Now, many individuals probably do need to fuel frequently, but the human body is certainly capable of functioning very well without fuel for longer than and higher outputs than modern society gives it credit for. It was not that long ago when running 100 miles was thought physically impossible.

Some of the endurance studies.
https://pubmed.ncbi.nlm.nih.gov/29628417/ https://pubmed.ncbi.nlm.nih.gov/30662406/ https://pubmed.ncbi.nlm.nih.gov/27669446/

 

[mtwarden]

^ I agree fueling is going to vary individually; for me it's when I get into the 2 hour-ish (and plus) range that I need to be thinking about fueling, under 2 hours I've thus far survived just fine

 

[unpossibly]

I like fasted cardio in the morning and weight training at night.

 

[doc holiday13]

I'm jumping in late on the game but there are different types of fast too.
I guess there has to be an end goal for what your purpose for doing cardio/lifting weights in a fasted state is. Are you trying to loose weight or boost performance?? An intermittent fast won't put you in a full calorie deficit.

If you're looking for max fat burn results from fasting and working out, you'll want to be in a true caloric deficit. A true fasted state (ie 24+ hours without sustenance) and working out will burn a lot of fat. I will do 48 hour fast occasionally and continue to workout but I don't think I've bothered to see if it makes a difference. You burn ~1500 calories just being alive. So if you go 48 hours without eating you're going to be in a 3000 calorie deficit. Throw 2 workouts in there with the assumption you're burning ~400 calories just working out, you have the potential to have burned ~4000 calories

The understood part of all this is that you are not eating like a chub chub. That being said, I think next monday and tuesday I'll refrain from eating but continue to workout hard and see what the does for me.

 

[mtwarden]

Bumping this up as I’m in my “forced” fasting exercise regimen- forced as in the weather sucks- we’ve been 90-100 degrees for a couple of weeks, with no end in sight.

Soooooo I’m on the trails when the sun is coming up to beat the heat.

8 miles (1400’) and about 2.5 hours without eating breakfast ( BIG breakfast when I got home ). No ill effect.

 

[Mike Islander]

Bumping this up as I’m in my “forced” fasting exercise regimen- forced as in the weather sucks- we’ve been 90-100 degrees for a couple of weeks, with no end in sight.

Soooooo I’m on the trails when the sun is coming up to beat the heat.

8 miles (1400’) and about 2.5 hours without eating breakfast ( BIG breakfast when I got home ). No ill effect.

Smart!

Been running 95+ here for days and days, with high humidity. Dewpoints high 70s and even 81 on Monday. Riding my dirt bike between 7-11 AM. Still hot, but not nearly as bad as the afternoons. I can ride with no food but prefer a piece of toast with lots of butter two hours before the ride.

 

[mtwarden]

When I was running mountain ultras, every year I said I would do some heat training the following year. The races where I DNF'd were all "hot" races, so it was obvious that I needed to do some training in the heat.

When the next year came around (like every year previous) I would still do everything I could to avoid the heat

Slow learner here

 

[Mike Islander]

When I was running mountain ultras, every year I said I would do some heat training the following year. The races where I DNF'd were all "hot" races, so it was obvious that I needed to do some training in the heat.

When the next year came around (like every year previous) I would still do everything I could to avoid the heat

Slow learner here

I'm blessed to be cursed with working in my warehouse all summer, lifting 50 pound sacks from ground level over my head and pushing 2500 pounds totes of liquid around. Best heat training I could ever force myself to do!

 

[mtwarden]

I've read enough research to know it's a good thing (obviously not taken to an extreme) with numerous benefits- increased plasma volume, lower hear rate, increase in VO2 Max- the list goes on. Knowing this and seeing my own results of poor performance in the heat—I still can't get out there and do it.

Maybe I should get a summer job roofing, road flagger or a hot warehouse like you