Experiment Fasted Training

This experiment is based on Dr. Jason Fung. and his 3 books.

So Ive tried fasting for a while now and have done 6.5 days 3 times. My definition of a fast is nothing but liquids mainly water, club soda or sparkling water. It is not a complete fast because I take in around 100 calories a day using electrolyte tables and the like. So not a true fast! I was also taking cream in my tea a few times a day but have stopped that.

Today I am at day 8 of this fast.
I’m hoping to share this information and document my journey and maybe help others out! Or freak them out not to do it :slight_smile:

About me. I started cycling in a June of 2017 at 265 lbs. When winter hit last year I bought a used tacx vortex and quickly started using trainer road. In 2017 I rode approximately 7000 km and this year I will break 12000 km. I turn 50 in February and currently my ftp is at 292.

So here is my last week and a bit.
Nov 9

Nov 10

Nov 11

Nov 12

Nov 13

Nov 15

Nov 16
Tech gym bike Bike at hotel
50:37 41 tss
Nov 17

Nov 18

Nov 19

I’m about to start sweet spot mid base II tomorrow. Thank you to forum users for pointing me in the right direction!!!

My weight tracking is
Nov 9 214.9
Nov 12 211.3
Nov 13 207.2 Between Nov 9 and Nov 15 I was losing a lot of water from my body from everywhere.
Nov 14 205.9 Now that that period is over weight loss has slowed but is progressing well.
Nov 15 202.3 I feel great and plan to continue this for a while.
Nov 17 198.8
Nov 18 198.2
Nov 19 196.9

I see my family doctor this week and will get a quick checkup and blood work done.

A calorie calculator tracked me at 2361 calories per day to maintain my weight. Depending on the day I am negative between 2261 and about 3450.

I’m enjoying this so far. My withings smart scale says my goal weight is 145 lbs. I have not weighed that since grade 5 so I do not think that is possible. But 160 would be nice and I would also like to get my ftp up to 320!
If the ride links aren’t showing up properly please let me know how to fix.


Thats a lot of weight loss in a short timeframe. From all I’ve read about rebounding, maintaining strength, easing body to new set point, etc, I’m not comfortable losing more than 1lb a week, or 4lbs a month. Stay safe!


Looking at the workouts you linked, you’ve done almost no work at higher intensity. What progress are you making to actually raise your FTP?

I bet you’ve dropped a bunch of water weight due to using up all of your glucose stores, but at what cost to your training? I’d rather focus on fueling my quality workouts to raise my FTP, personally.


The workouts I’ve shown have nothing to do with upping my ftp. Ive shown you the last week of sweet spot base mid 1. I just finished it as that is where I was in the program. I have dropped a ton of water weight!!! Mostly water to be sure. As for trying to increase my ftp that I hope will happen on this next training cycle starting tomorrow.

I’m hoping to be able to handle the increased work load as this new program starts. But if I have to much trouble with it I will lower the intensity. At this moment I am more concerned with dropping the next 37 lbs than increasing my ftp. At some point in the next 3 months I am going in for hernia surgery. The less I weight the better it will go. In 2 months I will lose a lot of power that will have to be built back up.

Yes this is common theory. In Dr Jason Fung’s the complete guide to fasting he goes through this scenario for people training. It should not be a problem at all (I hope). But I will be seeing a doctor often.


Nov 20
Ftp test. Dropped 6. Was damn hard. max heart rate went to 180 when my age says it should top at 171.
weight 195.8 Calories in 50

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6pt ftp drop is just statistical noise, nothing to worry about unless the next one is even lower.

The age-based HR rules are a load of bupkis. Sure, generally it declines with age, but it’s describing a population effect, not your personal range. Figure yours out from experience, and go by that. One thing to consider if your HR is higher than normal, you could be dehydrated. More salt and water are in order. And since you’re fasting, that’s very very likely.

Instead of linking all your workouts, you can just link to your calendar. I can pull it up just fine. And your career page.

Big fan of Dr. Fung’s work. I don’t really do any extended fasting, but his blogging a number of years ago really put me onto low carb and keto. Can’t fast forever, obviously, but carbs are definitely not necessary, even for cycling. Usually I’ll try to have some eggs morning of a race, but had my best cx race by far on Sunday skipping lunch and breakfast for a late afternoon race. Anyway, stick with it! Impressive results.


Thank you for your insight and support. Last night for the first time I noticed dry mouth. So You nailed it. Doubled up on my electrolytes and will have some bone broth today with extra salt!.
here is my calendar

Nov 21 194.6 lbs My ass is really starting get sore on rides. My longest ride this year was 11 hours and 311 km. I’m have trouble staying in one place and not sliding all over the place. I really hope this is temporary. Starting to miss the weight down there maybe!
Felling fairly good. A little soreness in the legs. Tomorrow is a much harder day so we will see…

so how do I link my calendar properly?

More salt, that’s my secret weapon for this year. If you want some reading material on it, checkout “The Salt Fix” by Dr. James DiNicolantonio.

Calendar link works. The preview isn’t very pretty, but I think it’s something to do with having to be logged in to trainerroad.com and how the forum software generates the previews. In general, if someone links a ride, you can also click on their name on that ride and it takes you to their career page.

You may find a new saddle or bibs are in order as you shrink. My longest rides are up to 150mi, and I think at the duration there’s no getting around a sore rear.

Nov 22
194 lbs
Rode Ebbets today. Left ftp at 292 and did not change to 286. Legs started hurting early about 15 minutes in but made it through. Feeling better overall with a lot more water intake. Not going to link the workout as my previous links should work to get there.
Should be in a 2919 calorie deficit today. Feeling pretty good with a little more back and leg soreness. But I have not done any bodywork on myself.

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Any updates? I’m embarking on a fasting journey myself. I’m 216 lbs and hoping to drop 50 lbs in the next year or so. I’m planning to do two or three 40 hour fasts per week.

I’ve been doing water/black coffee 24hr to 36hr fasts 3 times per week for a few weeks, plus a single 72hr fast in Dec. So far during SSB1 I’ve had one workout that needed a couple of back pedals and a bail on another - I ended up doing that one the day after, along with another weekend scheduled ride later in the day following a good amount of carbs. For me it is a fine line between getting enough carb reserves in for anything above sweet spot and the fasting schedule.

I’ve done low intensity sessions at any time, right up to the end of a 72 hr fast. Anything above SS needs to done early into the fast i.e. In the morning of a fast day or during an eating day. The weight is definitely coming off - and while there is some fuel in the system I feel strong (I even bumped my FTP up manually a couple of points mid Dec).

Have to say this is the first regime I’ve done that doesn’t feel like a constant battle of weighing, counting calories and tracking exercise - it’s simply timing and being mindful of sensible eating.

Looking forward to seeing if my FTP has suffered or not in the next ramp test due in two days and how the weight loss balances out against performance.


Why are you fasting? Health problems? General health improvement? Obesity? Athletic improvement? Eating disorder?

I’d do it immediately for health problems or obesity, but I’d expect athletic disadvantage from doing it, which would be worth it for better health or less obesity.

As I needed to drop a few pounds it was Initially the combined (potential) health benefits that other ‘diets’ just don’t seem to have that was the compelling factor to give it a go.

Further down the line it is the simplicity that I am finding is playing such a big part in keeping me on this path.

Tomorrow will be the first ramp test since fully embracing IF. So an interesting first report on athletic performance. Whatever that brings I will carry on through SSB2 and beyond with some degree of IF unless a significant negative arises.

For the first time I feel it could be a complete lifestyle choice - be that slightly fewer number of days per week depending on my weight


Well I hit quite a few bumps in the road that led to a lot of stress and emotional eating. Also had a few health issues to deal with (not related to fasting).

So Ive kept up the riding and am now sitting at 216 lbs (yes its been a very good holiday season for my stomach).

So today is day one again of my fasting regimen. Decided I’m starting today because if I misbehave tonight I will not be able to start tomorrow.

Most of my health issues have cleared up except for the inguinal hernia. It is a little larger in size than it was in November. Mostly due to a bad Fatbiking fall in the beginning of December (I couldn’t handle riding inside anymore). Ive also been looking at my fatigue levels using the elevate plug in off of Strava. It tells me my fatigue is at 67.8 %. I’m not sure how accurate it is but I have been riding almost every day for a few months. I am going to start using the scheduled days off in the program and go to the pool for some light swimming (not sure how hernia will take it) instead of riding.

Ive also just finished sweet spot base 2 and am wondering what program to switch to?

Anyways Happy new year to all.

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I would recommend you see about getting the hernia fixed. Look at your year and figure out when you can take some time off to have it done. You don’t want to wait until it is incarcerated and have it done as an emergency.

Ive been waiting since February to get it fixed. I actually found out I had it when it got incarcerated. Ive ridden 12000 km this year but I cannot walk over 1.5 km at a time without a long rest.

Hernia should be getting fixed in next 2 months.

Well I said I report back.
Age 56
193 lbs
Total weight loss since August 22lbs/10kg (target 189lbs then maintenance)
Ramp test - FTP unchanged since starting SSB1 240 (fast day - just coffee)

Bit disappointed in the FTP, but happy with the weight loss. Had a break from fasting yesterday and a few beers to celebrate New Years eve, so maybe not the best day for it. Might give the ramp test another go once the alcohol has cleared for a few days and shift it to a food day.

Does anyone experience headaches after working out fasted?

22 lb weight loss and same FTP is improving! Not to mention you were fasted and only in SSB1. I trust you’ll see a nice bump after SSB2.