What does long fasting do for cyclists?


A week ago I saw a video on the benefits of long fasting, 24-72 hours.
All I heard tho was talk about how it benefits you when you do not do any exercise.
Does anyone here know what happens if you fast as a cyclist.
I know that doing this while training probably isn’t the best idea.
Just like doing it during a rest week.
But what I had in mind was doing a 24-48 hour fast at the end of a rest week when you are fully recovered. 48 hours should be about 5000 Kcal of 700-800 grams of fat that you burn.
Or I’ll try to do a 24-36 hour once a week and see what it does to my workouts.
Sadly I can’t find what it does for endurance athletes.

The goal for me with this is losing weight since I still got about 10 kg of fat that I want to get rid of before my hilly cycling vacation.

Since the benefits you’re seeking are weight loss AND performance, I’d recommend trying intermittent fasting. If you’re doing TR plans then that means you’re only going to be doing 1 fast every 6 weeks, unless you start having a knock-on effect on your training.

The key thing about this and other eating habits is they need to become a regular routine rather a diet. It needs to be a lifestyle. For me personally, I found that intermittent fasting, since I did it every day, was a lifestyle that was easy to adopt, whereas doing something once a week is much harder to maintain consistently over months and years.

The one thing I’ve learnt through experimentation is that general good, healthy habits that create a small but consistent calorie defecit are much easier to stick to and therefore more likely to be successful than other more faddy approaches such as fasting or strict diets.


Well I get what you’re saying but what the long fasting is supposed to do beter is the decrease of muscle lose while in calorie deficit.
And as far as lifestyle goes. I’m willing to train 4 times a week and eat healthier but food discipline has always been a bitch for me. Eating les leafs a choice of what to eat and I miss use that. So not eating seems more doable.
I will try it at the end of this week. Sunday and Monday.
Here is the video I say btw.

Is this your only goal, or is it paired with another goal? Do you want to lose 10kg and maintain fitness? Lose 10kg and gain fitness? Simply lose 10kg?

Further, how far away is your cycling vacation? 6 days? 6 weeks? 6 months?

I think the answer to your question is different depending on what you are chasing and when you are trying to achieve it by

Well losing fitness is never a goal so maintaining fitness or gaining fitness is the goal.
Vacation is now that I think of it in 6 weeks so 10kgs isn’t doable.


I would go further and suggest that maintaining fitness while dropping weight is probably the goal you should aim for. Gaining fitness during weight loss is very challenging, particularly if you have struggled with your diet in the past and expect that to be a a tough hurdle for you to clear.

As @onemanpeloton mentioned - it is important to view diet changes as permanent and not as temporary solutions. If you want to use longer fasting as a technique by which you lose weight you should consider doing it on a consistent basis.

That said - I would gently steer you towards a better overall diet as opposed to any sort of fasting. Since you’ve mentioned that you struggle with self control an all or nothing approach like fasting will likely lead to you breaking down and binging at some point.

Instead I’d suggest that you introduce healthy foods that you enjoy in greater quantities over time. You can still have the unhealthy things, you just need to keep track of them. Whether this means you track your entire diet consistently using something like MyFitnessPal or a more casual approach is irrelevant (although - please consider doing 100% tracking including weighing your portions for 1-2 weeks just to get an idea of how much you’re consuming) if you can be honest with yourself about what you’re eating and where that is coming from.

Not only will this approach be more sustainable by the majority of people but it will also avoid the fast/binge paradigm that many ‘dieters’ end up following.

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Just look at the thumbnail of that video and ask yourself if you honestly want to base a decision as severe as not eating for three days on that.


If you want a deep dive into what happens with prolonged fasting, check out Rhonda Patrick’s presentations on the subject. 2 years ago I did a 4 day water fast. I had been doing a prolonged intermittent fast (6 wks) consisting of one meal/day prior to that. The 4 days were actually pretty miserable. I read you have to go 5 to 6 days before you completely convert to burning fats. I lost about 8 lbs (4 kg), but it all came back once I started eating. Weight loss was not my goal.

Ive been intermittent fasting for over 2 years now. Its the way to go with training. I ride fasted in the mornings at Z2 intensity, and fuel for the harder workouts in the afternoon/evenings. I eat breakfast before long days on the weekends. I treat it simply as an easy way for me to restrict calories and any fat adaption that occurs is a bonus, but I can ride for 3-4 hours now on just water

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You’ve been intermittent fasting every day of your life, that’s what sleeping is.

Fuel your workouts either with complex carbs 2+ hours prior or simple carbs during. Eat at a small deficit, 200-400 kcal/day, for the rest of the day if you want to lose weight.

There’s no magic to any of this. Track your weight, track your intake. Make the number of calories going in slightly smaller than the number going out. Everything else is layers of bullshit to sell books.


The longest I’ve gone is 13 days fasted. Had no effect on my training. After 36 hours I felt great. But on the 13th day my family ordered pizza… I’m so weak… lol


13 days!!

How does that work? You just don’t eat for 13 days, or you do eat a bit at certain times? Are you able to function at all?

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As a chemical engineering PhD I very much believe in the thermodynamics of CICO, but how many people do you know who track calories religiously for years on end? You would think cyclists who are data driven would have these, yet I don’t know a single one who does, even with apps nowadays. This completely ignores the psychology that deals with long term weight loss. There are lots of ways to skin a cat and the most effective one is the one someone will actually follow

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I recently cut 7 lbs from 158 to 151 using calorie counting and TDEE calculators, while doing vo2 and threshold work. It’s pretty brain melting doing it for more than 3 months but it works. For maintenance using Endurance Diet techniques and ‘eating clean’ are going to be way more sustainable.

How you state things you will never find anything new and that is not what I’d like to do here.
Questioning the common knowledge is what led to SKY dominating the sport.
Simple calorie counting is an effective but old methode.
What I tried to do with this tread is to ask, what if you let go of this and try this.

Sleep, on point :joy: and its SO MUCH EASIER.

Going through MyFitnessPal seems to confirm this for me. I’ll calorie count for a month or three then stop. Repeat after a few months…

Just couldn’t see myself doing something like this daily. Bet most Pros don’t either. Maybe some people go full on and just eat the same thing daily so they can simply do a few swipes each day and have a pretty accurate calorie track for the year.

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