Your workouts during the fasting period should be kept low intensity, z1/z2. If you try to do quality efforts while fasted, youll bonk early and feel fairly wasted afterwards due to glycogen depletion. (Fatigue, brain fog)

What you are doing is essentially glycogen manipulation. Fasting will work to drain glycogen stores, promoting the release of fat into the blood which can then be used for energy. You then restore glycogen with compkex carbs during the eating period and the cycle repeats

Make sure you get ample carbs in, complex carbs (rice potatoes), during your eating period to restock glycogen stores. I would also suggest sipping 30-50g pure sugar in right after your workouts to help the body feel a bit better. You can easily get into a cycle of feeling like crap if you undereat carbs and over intensify fasted workouts

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Strava

I'm going to disagree with the precious response you got, you do not have to go easy or lower HR. I have been doing this IF for about 3+ years now, and I hammer my morning workouts as hard as ever. Like you, I keep most at an hour or under, and even when I do two of them, never had a bonking problem. In fact, I just got more efficient over time and still do not get hungry afterwards.

Now if you were ironman training and doing 3+ hours a day, then that would be a different story. But apparently you are not, so go for it!!! The way I look at it, fasting will net you your BMI calorie burn for as long as you do it, but doing some workout that adds 400 to 800 calories in a very short period to time, is just supersizing that burn. Could be a half day to get an 800 burn, but between an hour to two you could get that same amount, on top of the BMI burn too...

I’ve worked out into a fast and would just say best practice is to have a protein / fruit smoothie on hand to break the fast when you can’t hold on anymore. I basically mean pushing a 16hr fast to 18hr, etc. There is much relief if you know you have a nice 32oz smoothie nearby.

Keep in mind also that Gatorade and gels will break the fast, so plan accordingly.

If you’re trying to do longer fasts, I’d suggest breaking the fast with bone broth before you eat real food again. These are pretty good:

https://www.amazon.com/...f=pd_basp_dp_primary

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https://www.strava.com/...tes/zachary_mckinney

Depending on who you listen to/read so does coffee but I have a cup around 9 each morning.

My time restricted window Monday through Friday is also 12-8 but I’ll push it to 2 some days depending on my schedule.

Easy runs in the morning 3 days a week with easy bikes in the evening.

The other two days I don’t run in the morning during the week reserved for workouts in the evening.

I’ll have to switch it up during the summer when evenings are too hot for a run workout

Weekends I’ll eat before rides but usually don’t before my two hour run. Depends on how well I replenish carbs the night before.

I listen to a nutritionist who has her MS in Nutritional Science from Columbia. She says coffee doesn't affect the fast as long as the calories in the creamer are less than 50 calories.

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https://www.strava.com/...tes/zachary_mckinney

Dr. Rhonda Patrick says that “drinking black coffee breaks the fast because it contains caffeine which affects our brain, gut, liver, etc., all of which affects your biorhythm clock.”

Like I said I drink black coffee in the mornings. I don’t think it impacts me but I also don’t count my calories. I eat less during time restricted eating because I’ll often eat because I want something in the evening not necessarily because I’m hungry.

I think the biggest difference for me is less alcohol due to stopping at 8 evenings. That’s just dead calories.

If we are talking about Intermittent Fasting, it absolutely doesn’t break the fast. Black tea, green tea, water, coffee are fine. There is no disagreement here.

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https://www.strava.com/...tes/zachary_mckinney

cream or creamer.... creamer has lots of synthetic fats, and sugar.

also gatorade zero wont break the fast.

ok

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https://www.strava.com/...tes/zachary_mckinney

Again, I said it depends on who you listen to. Rhonda Patrick is pretty reputable.

Google if it’s okay to drink coffee during intermittent fasting there’s arguments from both sides.

Peter Attia: who has a background in distance swimming

It depends on your objective
If you’re practicing time-restricted feeding for weight loss/calorie restriction:
Black coffee won’t affect this
Caffeine/black coffee can actually help mitigate hunger
If you’re practicing time-restricted feeding to help gastrointestinal issues/rest the gut:
In this situation, coffee would break the fast (it would be altering the gastric pH and lots of stuff related to it)
If you’re practicing time-restricted feeding (or doing a longer fast) for autophagy purposes (autophagy is essentially the process by which your body breaks down damaged cells/cellular components):
In short, we don’t know – we can’t measure autophagy in the body
For herbal tea, it’s a little different (it’s probably okay to consume during a fast – it’s not thought to affect autophagy)

Understood.

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https://www.strava.com/...tes/zachary_mckinney

To answer your question:
Yes, have tried roughly the same schedule you outlined. And no, didn't have any problems with the workouts. I've found that I feel stronger during the workouts following the 24 hr fast.

It might be an adrenaline rush. But it was enough to last for a couple of hours of workout, or through a shorter high intensity workout.

I do drink black coffee.

Caveats: i have more than 10lbs to lose to get to where I need to be, so maybe that helps - there's definitely extra "reserves". And I'm nowhere near pro speeds, so at this point in my training, dropping weight is going to help my performance a lot more than a couple gels will.

That’s good to know that you were able to train at the end of a 24 hour fast. Thanks for sharing. I used to be a runner and weighed 160 lbs at 5;11”. Now I only ride and am 180 lbs. To be honest I need to lose closer to 15 lbs. The frustrating thing is that cycling fitness is not helping my weight at all. I just keep slowly gaining a few lbs each year. I was never as strong on the bike as I am now, but it doesn’t help when I am climbing hills. The extra 10-15 lbs is tough to haul up the steep hills we have in this area (northern Connecticut). Every ride I do ends up with 1000 feet of elevation gain per hour.

I also live in northern CT, right near Bradley airport. Maybe ive seen you at some point! Maybe i can help you out a bit with your weight loss goals...

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Strava

Pieman wrote:

I am struggling with trying to lose 10 lbs and am going to try intermittent fasting. I have read Dr. Fung's book and done some more research on the benefits of fasting and want to give it a try. My plan is to do 16 hour fasts during the week, so only eat between the hours of 12:00 and 8:00, and two of those days do a 24 hour fast. I usually ride early evening before dinner, or at 6:00 a.m. I have had no problems doing a morning ride and then not eating until noon. But I have not tried riding at the end of a 24 hour fast. Has anyone else tried IF and had problems with completing a workout at the end of a 24 hour fast?

My weekday rides are all an hour or less. I ride longer on the weekends and would not fast during those days.

Just to be clear here.... there is zero evidence that IF works any better for any general population health, weight loss, body composition, or sport performance purpose than normally timed meals.

There is evidence that if it helps you adhere to a kcal deficit, on average, over time, you will lose weight. If it works for you (it does for some folks!) then great. I am not saying not to do IF. Just cautioning that it doesn't carry special physiological benefit.

"Mechanism, therefore application" is the fastest way to folly in exercise and sport science. It works better in limited-dimension systems, like engineering and physics. Not so much in infinitely multidimensional biological systems that have a nasty little thing called homeostasis to maintain. Negative feedback loops often shut down acute responses to anything, and totally negate and erase any potential gain that might theoretically exist if the acute effect were to continue indefinitely without interruption. Pesky homeostatic mechanisms!

4 prominent examples that has gotten loads of folks in the sport science community caught with their feet in the mouths:

1. Low-rest hypertrophy training causes a larger post-exercise testosterone and growth hormone increase, therefore it's better or even essential for muscle growth. Truth: More inter-set rest is better >90% of the time.
2. Post-workout carb:protein intake ratios like "4:1" results in higher circulating anabolic hormones, therefore bigger muscles or better recovery. Truth: Ratios don't matter.
3. Fasted training increases fat-burning during training, therefore it will result in more fat loss or weight loss chronically. Truth: There is no body composition or weight benefit chronically.
4. Higher fat oxidation rates with high-fat low-carb chronic diet, therefore improved exercise performance. Truth: there is no benefit and may be harm to performance.

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Dr. Alex Harrison | Founder & CEO | Sport Physiology & Performance PhD
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I am in Simsbury and ride all over the Farmington Valley area, as well as Granville, Suffield, etc. As you know the farther west you go, the more hills you encounter.

My brain doesn’t seem to want to let me reduce calories. It is very frustrating. And it’s not as easy as “put the fork down” as some people think it is.

You don't have to put the fork down, just cut out rubbish food and you can eat until you explode.

I dare anyone to try and get fat from eating as much vegetables and lean meat as they could stuff in their mouths.

Granville and rt 44 is quite a thing. I worked in simsbury so i know around there can be fairly brutal as well.

The best phrase i learned was ‘the fat you eat is the fat you wear’. I have found this to be very true, and have had the most success with weight loss, performance and well being from a starch based diet (McDougall diet but with lean meat like fish)

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Strava

Big fan of fasting, be it IF or multiday. Good advice here already. Put me in Monty's camp, this should be very doable for you.

Only advice I would add is to make sure you are monitoring electrolytes. There are lots of ways to get them, but I have found it easiest to take a supplement nightly with my other vitamins and I have a saltstick or two after I eat. Some people will just mix salt(sodium) and no salt(potassium) into other beverages and there are myriad ways to achieve this. This is a must in multiday fasting and I find it necessary doing IF and I train 10h week.

Lots of other benefits, all outlined in Dr. Fung's book.

Good luck to you.

I use IF 5 or 6 days per week depending on workout/racing schedules. I do 18:6 and eat from 12noon to 6pm. I typically workout at 4pm so IF works great. I eat a nice, healthy lunch at noon and then 4 hours later I work out after the food has digested. Then when my workout is finished, I shower and eat a nice dinner at 5:30 to 6pm. I do polarized training so if it is an intensity day I will ingest SIS gels to help provide extra fuel for the workout. If I have an early morning race/group ride then I simply do not fast that day. It's so simple and I've been able to lose 15 pounds and keep it off. Don't make it more complicated than it needs to be.

Big fan of fasting, be it IF or multiday. Good advice here already. Put me in Monty's camp, this should be very doable for you.

Only advice I would add is to make sure you are monitoring electrolytes. //

This is great advice I forgot to add in. For me I take a couple saltstix's in the morning during my fast and my black coffee drinking. Otherwise I tend to cramp at the noon workout. The lack of eating, the diuretic affect of the coffee, all tend to bleed electrolytes in some people, but me especially. Some folks dont have this problem, so you just have to figure out if you are in that camp or not.


And to those that are posting up studies and other stuff going against IF, this is a very new and complicated thing to really access. There is a ton of anecdotal evidence that it does many of the things claimed, and even some studies. But like with anything new, the proponents often go too far in their claims, and the detractors often latch onto those aspects to say, see I told you it was bunk. And of course it is going to be somewhat individual, just like diet is. Everyone will not react the same to this stimulus, but there will be some broad generalizations that will be true. It may not be a great way to lose weight, but could be a great way to reduce your bodies inflammation. I have posted over the years my experience with IF, and it has been all positive, not only in feeling, but in actual blood work results. Pretty sure your blood does not react to a placebo affect...

monty wrote:

I have posted over the years my experience with IF, and it has been all positive, not only in feeling, but in actual blood work results. Pretty sure your blood does not react to a placebo affect...

Same.


A1c don't lie!

I’m going to resurrect this thread because I haven’t found very many on ST in searching.

I’m going to give this a go and I’m wondering what others are doing for protocols, if you want to call it that. It seems a lot of people are doing at least 16:8 or 18:6, and even as a beginner I see no problem adopting this.

But is it daily? Alternate days? 5 out of 7, and is so what do the non-fast days look like and would you do those days back to back?

Also for anyone doing it for a while, have you noticed or implemented any broader changes in your food choices?

I’ve been struggling for years really, to get weight back to something approaching race weight. I don’t really care about training effects as such, because I haven’t been training and I’m keeping myself to easy Z1-2 efforts on the bike and run for the coming months. So training fasted isn’t a concern for me.

I eat dinner between 5-6:30p with the kids and then don't eat again until lunch the next day which is some time between 12-1p. All of my training happens fasted in the AM. I am nowhere near IM fit, but think of an average training day being 3 hours of exercise. I don't even think about it at this point, but when you first start the first few days will be a challenge. After about a week it should be a non issue and you won't be hungry at all.