fasted exercise

mtwarden

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Soooooo.... it's been hotter than hell here going on three weeks, which has forced me into hitting the trails early (thankfully we're cooling down by morning!); early enough, it's easier to get my hour to two hour hikes in before eating breakfast.

I've read about fasted exercise a fair bit on the Uphill Athlete site. Their take is that fasted exercise helps the body better activate fat calories on longer events (ie endurance ie hunting :D). Evidently after 12 hours (6 at the very least) your glycogen stores are depleted, so recruiting needed calories (if you haven't eaten) comes from fat.

They also stress that this fasted exercise should be on the lower key end- not sprinting, not HIIT, hiking/running/biking at a lower heart rate- their "zone 2". I don't use a heart monitor, but from my reading I think I'm pretty solidly in zone 2 most of my hiking (probably zone 3 on some of my longer climbs).

Not a weight loss strategy as near as I can tell, just a strategy making a person more efficient moving through the hills/mountains by utilizing body fat in addition to calories consumed while out. They do stress that for an actual "event" you want to hit the calories pretty hard (leaning more on carbs as they metabolize quicker)

I don't notice any less energy w/o breakfast or anything else much out of whack; but breakfast sure tastes good though!

Anyways I've read about it several times, never really considered it, but now by happen chance- I'm doing it :)

I don't think there is anyway (save some expensive, complicated scientific testing) to quantify results, but thus far it sure hasn't hurt anything.
 

TSAMP

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Suprised you don't utilize a simple smart watch for HR monitoring. I've found my garmin to be fairly accurate and helps tremendously when I need to set a pace for myself.
 

Ratbeetle

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I'll sometimes do fasted cardio in the mornings, well semi-fasted as I have my black coffee first. I like it for longer low intensity sessions on recovery days.
 

jzeblaz

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I do most of my exercise in a fasted state and I haven't had any issues. I've fueled some low stakes bicycle races with low carb diet (not sugar as is commonly used) and performance was dismal. I guess it depends how long and hard you're going and what your expectations are. If you don't feel like you're going to pass out or are overly fatigued, you're probably just fine.
 

Marbles

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I like fasted training. I'm still working my way through Training for the New Alpinism, but from the military on have worked out before breakfast a decent bit.

Most of my training is zone 2 (which per training peaks and my lactate threshold and max HR is actually a pretty fast HR). I have done 24 miles without eating, predominantly in zone 1. At 24 miles food changed nothing for my body, but it sure was nice mentally.

From a raw survivability standpoint, it helps. Even from a hunting standpoint, it is nice not needing to snack during the day.

A basic HR monitor is a good investment, but I resisted getting one until early this year. It has helped me avoid overtraining.
 
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mtwarden

mtwarden

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Suprised you don't utilize a simple smart watch for HR monitoring. I've found my garmin to be fairly accurate and helps tremendously when I need to set a pace for myself.

I'll look at my watch (Garmin Instinct) occasionally but it's not revealing too me to me (unless it's spiking) as the whole Aet, AeN, etc thing confuses me :D

When they say zone 2 means a decent effort, but still being able to converse normally- I understand that
 

Marbles

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I'll look at my watch (Garmin Instinct) occasionally but it's not revealing too me to me (unless it's spiking) as the whole Aet, AeN, etc thing confuses me :D

When they say zone 2 means a decent effort, but still being able to converse normally- I understand that
It is really only meaningful if targeting a range. I will keep an eye on mine and ease up if HR gets above range or push harder if below. I set the HR zones on the Garmin to match those from TP, so if targeting zone 2 it is just a glance down to make sure it is in the blue. I bounce around in the target range, even on pretty level runs, and ignore it.
 

jofes

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Suprised you don't utilize a simple smart watch for HR monitoring. I've found my garmin to be fairly accurate and helps tremendously when I need to set a pace for myself.
It's also interesting on their forum that they state data from wrist watches is unreliable, they only want you using chest straps.
 

TSAMP

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It's also interesting on their forum that they state data from wrist watches is unreliable, they only want you using chest straps.
Totally believeable. I suppose like anything it's ballpark information. Mine actually malfunctioned and the light intensity burned my wrist. It blistered before I took it off. Felt like a shock at first.

And here I am wearing one still.
 

P Carter

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I'll look at my watch (Garmin Instinct) occasionally but it's not revealing too me to me (unless it's spiking) as the whole Aet, AeN, etc thing confuses me :D

When they say zone 2 means a decent effort, but still being able to converse normally- I understand that
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.
 

Mike Islander

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On morning dirt bike rides I don't eat anything. The dirt bike rides are about an hour or more, with a heart rate average of about 150 - 160 and peak at 180. But for BJJ I eat a banana and cup of applesauce about 30 minutes in advance. Definitely makes a difference for ultra hard cardio, where I'm averaging a HR of about 185 for 16 minutes, with 30 second rests between the four 4-minute rounds.
 
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*zap*

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So here is my take on this:

Your body will use the low hanging fruit (glucose/insulin) to make atp even if your @ a low intensity heart rate.

If your fasted then you have no insulin or glucose in your bloodstream....(coffee is fine and your still fasted if you had it black/no sugar). So your fasted and keep it @ low heart rate which will not encourage the body to release any glucose to make atp. Your body then is making the atp by using oxygen to burn fat. This is not as e-z for the body as using glucose so....over time your body will change at the cellular level....mitochondria will enlarge or split, your capillaries will become denser to provide more oxygen and you will make more aerobic enzymes.

So your body will work to become more efficient at using oxygen to burn fat to create atp. The longer your durations and the more frequent your sessions the more you will stress (encourage) the body to become more efficient at this process (change at the cellular level).

You have to accept that these processes will take time and then you just do the work regularly and slowly increase your durations and frequencies...years. That is building your aerobic base.

Personally I am at 45 minutes and then I sit and have a cliff bar (mini or regular bar depending on a few factors like time to finish, how I feel, temp and difficulty of that hike) and continue...should get up to 75 minutes and then a rest/bar for my high end since I do not see the point of stressing my body any further than that for this year.

Once I got to over 45 minutes duration I started every other day instead of every day,...but I also lift every other day so there is a limit to what is practical.
When you do this on a dedicated schedule 3-4 times a week your really doing it right vs just doing it at random frequency.

When you have adapted to the stress of doing these workouts regularly then add a few shorter high heart rate sessions a month with plenty of time for recovery after and do those sessions fueled. I like the cliff energy bars to fuel more intense exercise.

ymmv.
 
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mtwarden

mtwarden

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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.

That's very possible; like I mentioned no odd/ill effects the last couple of weeks going without calories before my morning hikes (1-2 hours, one hike was 2.5 hours)- nothing overly strenuous though
 

eamyrick

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I’m doing only black coffee until 11a. I tried evening fasting and don’t prefer it as I’m usually hungry. I never wake up hungry and actually feel like my performance is the same with morning PT. There is an adaption period to anything so I would definetly try it for a few weeks before you decide what’s works best. Black coffee and no food is definetly way easier to get the day started.
 

Patriot2

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I started doing both cardio and weights in a fasted state in the mornings - eating only between 11:00 AM and 8:00 PM. Been doing it since february and no loss of performance that I can tell. Being on a low carb diet my energy stays very stable the entire day - which I have come to enjoy. Tom DeLauer said you produce less lactic acid if you exercise in the fasted state. I can say I am never very sore the next day no matter how hard I push myself, so there may be something to it.......or not.
 

Coldtrail

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This is interesting, I used to do this years ago when I was training for a lot of endurance sports with decent results. I also was a wildland firefighter in the late 80's early 90's and had to eat to stay in decent shape and energy for that as well. Once I was working full time in the late 90's I got into the middle aged guy breakfast habit and less endurance workout, but I have run hounds a few days a week Oct through March for all of my adult life which is a pretty good workout for the most part. I'm now 51 and in the past 5 or so years I have been able to get far more time in the woods and my endurance workout the past couple years has been chasing behind hounds all winter about 5-6 days a week so in the off season I do about a 2hr level 1-2 low intensity walk each morning with my pack mixed with some more intense cardio on/off. For a while I was fasting but noticed that it really didn't take much of any kind of increase in intensity to put me into sort of a burnout where I'd be hungry and shaky. I tried the fasting on hunting days and any elevation or snowshoes on my feet and I would burn out quickly. I started to eat a breakfast and noticed a little boost, but likely more psychological.

What I did to fix that was really go line by line through my diet to maximize my daily calorie intake & basically try to take in valuable fuel instead of junk and make sure I do that everyday. I found that even my perceived "healthy" eating was messing me up a bit, once I got that balanced out I dropped about 10lbs and leveled off and my lower intensity ability is about endless even skipping breakfast & if I need to go into aerobic higher that I can for short bursts daily as long as I eat good and consistent food on a regular basis. I think I have found the sweet spot for hunting, can walk anywhere for any length of time and take it up a notch occasionally if needed, and do this several days in a row fasting or not.

Everyone is different, but for me once I really picked my diet apart & replaced a few supplements with actual food and got my protein/fat/carbs dialed in better and more consistently it seems like I can really maximize my daily performance. I still carry quick energy food and hydration stuff in my pack, but more for the "oh $hit" days where things go sideways. Other than that if I'm out all day I just pack a small "lunch" that has my balance of food to eat more so to get me through the next day, what I need at 51 is much different than what I was doing at 30 or even 40yo and it now becomes a 24hour process to maintain that.
 

Mike Islander

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You do enough aerobic capacity low intensity training and your low end will be like someone else mid end...raise your aerobic threshold and anaerobic threshold from the bottom up....when you do that it positively effects your quality of life.

Are you saying if you concentrate on ACLIT that you will have poor aerobic capacity and need to work harder?
 
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