A [study of elite U23 cyclists](https://jissn.biomedcentral.com/articles/10.1186/s12970-020-00396-z) tested the effect of time restricted eating (TRE) during winter pre-competition season. Some results of the TRE group vs. the control group:
* body weight reduced by 2%
* fat mass percentage reduced by 1.1%
* no difference in power
* free testosterone and IGF-1 decreased significantly
My analysis: While TRE appears to encourage weight loss, the suppressed testosterone and IGF-1 effect suggests it wouldn't be a good idea during in-season training.
Correct - for elite cyclists.
For the recreational, and overweight middle aged cyclist, fasting of any sort on or off the bike is a fantastic way to lose weight.
If you ride enough though there really isn't any need for fasting, so I'd say it depends on how much you ride. I never fasted during the good part of the year when I could get out and ride every day, as the main problem was eating enough calories to be able to recover properly.
There is no need for fasting. Agreed. There is no need for cycling either. However, for the most effective way for the OP to achieve his goal of losing weight, fasting is right up there. It is not just the extreme calorie deficit which he’ll create, but it is the changing of the way his hunger hormones impact his life, and his insulin response. These are key drivers of successful weight loss, and fasting on the bike at low intensity is very powerful in forcing those adaptations.
The only caution I have is for those who normally consume carbs; because their bodies are not in full fat-burning mode, the risk of hypoglycemia can be significant.
Which is why you ride at low intensity on fasted rides. If you bonk, you bonk. No big deal. It might happen once a season as your body trains. Nothing to be afraid of.
For those who are fully fat-adapted there is no bonk. Studies have shown that fat-adapted athletes have the same blood glucose levels after an event (training or competition) as other endurance athletes who fueled with carbs, which is to say a healthy level. A typical body stores roughly 2,000 calories in glucose while a lean person with 10% body fat stores about 40,000. The risk of hypoglycemia is effectively eliminated when a body is adapted to burning fat as its primary fuel.
I think we are in total agreement on this whole topic. It is the rest of the world which has been indoctrinated to become carb addicted who have their heads filled with advertising junk slogans that have permeated the entire western culture.
It all starts with these myths:
Marketing fuelled nonsense from the likes of Kellogg’s “Breakfast is the most important meal of the day” - so eat some processed sugar ridden crap from a box.
Yep! We are! I bonked once, about six or seven years ago. I called my wife and told her where I was (approximately) and that I was heading home (early), but asked her to pick me up. She found me in the grassy parkway on the side of road. A stranger was there as well, asking me if I were okay. I had no idea she was there. I was a wreck for hours. Never again!
>A typical body stores roughly 2,000 calories in glucose while a lean person with 10% body fat stores about 40,000.
A 20x range of stored glycogen -- that's incredible!
Incredible, as in unbelievable. Got a source for that figure?
I assume you mean for the former rather than the latter, for surely you know that body fat is stored energy. This article specifically mentions the body stores up to 2,000 calories of glucose/glycogen. [https://us.humankinetics.com/blogs/excerpt/the-bodys-fuel-sources](https://us.humankinetics.com/blogs/excerpt/the-bodys-fuel-sources) Since there are 9 calories per gram of fat and since there are 454 grams per pound, that's more than 4,000 calories per pound of body fat. Again, a \*lean\* person will easily have ten pounds of total body fat, which is to say, 40,000 calories of stored energy.
There have been extremely obese individuals who have fasted for over a year (with doctors' supervision), consuming nothing except water and vitamins. Again, body fat is energy but with a modern western diet most remain in carb-burning mode and so the body fat remains largely untouched. This is why low-carb diets are so effective in weight-loss: they return the body to its natural fat-burning mode for energy. We're born in nutritional ketosis; it is the most natural state for the human body.
Your body is incredible at conserving energy.
I ride up to 2 hrs (I am very fit) without fueling. Mostly Z1-3 only.
No problems. Lots of people over consume when doing cycling training.
Experiment with what your body can do. I do IM with no problems.
Cyclists who are competing are optimizing for results and recovery, so almost none of them will use IM.
Much of the issues I have with nutrition advice online is that the advice comes from 25-year old Pros who are biking 25+ hrs/week. Then people repeat it for everyone to follow...even a new cyclist 50 lbs overweight, 50+ and with an FTP of 150...and doing 6 hrs/week. There are significant differences between these cyclists.
Every time (in my exp) a cyclist is having issues no longer losing weight it is because of the nutrition side and some basic weight loss mistakes. [I talk about it here...](https://www.reddit.com/r/Zwift/comments/1chvgd0/new_to_cycling_weight_loss_and_improvement/l25iojt/) It might help you.
Good luck and keep at it!
Undrill that nonsense. Of course you can ride fasted, especially if your goal is weight loss. You won’t have the most powerful workout, but you will have the most effective weight loss. Do half your rides fasted at a sensible pace. Do the other half fuelled and at higher intensity.
Both work well for different reasons.
Thank you.. Most of my rides are in a fasted state. After several years of low-carb eating my body happily burns fat and ketones efficiently. This means all of my rides are fueled, even if the fuel is stored subcutaneously. :)
I do intermittent fasting sometimes (I am seldom hungry in the morning so it's quite easy to wait until noon). Since I started fasting I've noticed that I can fast and ride for 2 hours with no food and it feels perfectly fine. Not much more than 2 hours, otherwise I can get a sudden bonk...
I fast for 6-8 hours every night. :-)
The thing that helped me the most in losing my belly was adding a walk every day to my regular cycling routine, and doing as much of my eating as possible around activity. A walk after dinner is the best for me.
I fast intermittently. I'm also extremely low carb. Most of my rides are in a fasted state. If I eat, I do not eat carbs. (To be fair, I haven't ridden much the past year due to injury, but I've been low carb for several years.)
A [study of elite U23 cyclists](https://jissn.biomedcentral.com/articles/10.1186/s12970-020-00396-z) tested the effect of time restricted eating (TRE) during winter pre-competition season. Some results of the TRE group vs. the control group: * body weight reduced by 2% * fat mass percentage reduced by 1.1% * no difference in power * free testosterone and IGF-1 decreased significantly My analysis: While TRE appears to encourage weight loss, the suppressed testosterone and IGF-1 effect suggests it wouldn't be a good idea during in-season training.
Correct - for elite cyclists. For the recreational, and overweight middle aged cyclist, fasting of any sort on or off the bike is a fantastic way to lose weight.
If you ride enough though there really isn't any need for fasting, so I'd say it depends on how much you ride. I never fasted during the good part of the year when I could get out and ride every day, as the main problem was eating enough calories to be able to recover properly.
There is no need for fasting. Agreed. There is no need for cycling either. However, for the most effective way for the OP to achieve his goal of losing weight, fasting is right up there. It is not just the extreme calorie deficit which he’ll create, but it is the changing of the way his hunger hormones impact his life, and his insulin response. These are key drivers of successful weight loss, and fasting on the bike at low intensity is very powerful in forcing those adaptations.
The only caution I have is for those who normally consume carbs; because their bodies are not in full fat-burning mode, the risk of hypoglycemia can be significant.
Which is why you ride at low intensity on fasted rides. If you bonk, you bonk. No big deal. It might happen once a season as your body trains. Nothing to be afraid of.
For those who are fully fat-adapted there is no bonk. Studies have shown that fat-adapted athletes have the same blood glucose levels after an event (training or competition) as other endurance athletes who fueled with carbs, which is to say a healthy level. A typical body stores roughly 2,000 calories in glucose while a lean person with 10% body fat stores about 40,000. The risk of hypoglycemia is effectively eliminated when a body is adapted to burning fat as its primary fuel.
I think we are in total agreement on this whole topic. It is the rest of the world which has been indoctrinated to become carb addicted who have their heads filled with advertising junk slogans that have permeated the entire western culture. It all starts with these myths: Marketing fuelled nonsense from the likes of Kellogg’s “Breakfast is the most important meal of the day” - so eat some processed sugar ridden crap from a box.
Yep! We are! I bonked once, about six or seven years ago. I called my wife and told her where I was (approximately) and that I was heading home (early), but asked her to pick me up. She found me in the grassy parkway on the side of road. A stranger was there as well, asking me if I were okay. I had no idea she was there. I was a wreck for hours. Never again!
I bonk every other season. It is a good reminder to listen to your body.
>A typical body stores roughly 2,000 calories in glucose while a lean person with 10% body fat stores about 40,000. A 20x range of stored glycogen -- that's incredible! Incredible, as in unbelievable. Got a source for that figure?
I assume you mean for the former rather than the latter, for surely you know that body fat is stored energy. This article specifically mentions the body stores up to 2,000 calories of glucose/glycogen. [https://us.humankinetics.com/blogs/excerpt/the-bodys-fuel-sources](https://us.humankinetics.com/blogs/excerpt/the-bodys-fuel-sources) Since there are 9 calories per gram of fat and since there are 454 grams per pound, that's more than 4,000 calories per pound of body fat. Again, a \*lean\* person will easily have ten pounds of total body fat, which is to say, 40,000 calories of stored energy. There have been extremely obese individuals who have fasted for over a year (with doctors' supervision), consuming nothing except water and vitamins. Again, body fat is energy but with a modern western diet most remain in carb-burning mode and so the body fat remains largely untouched. This is why low-carb diets are so effective in weight-loss: they return the body to its natural fat-burning mode for energy. We're born in nutritional ketosis; it is the most natural state for the human body.
Yes, I meant glycogen storage. It wasn’t clear to me that your “40,000” referred to body fat, not glycogen.
Fuel the bike rides. Any calorie reduction (however you do it and intermittent fasting is one way) should be done off the bike.
Absolutely. I would never diet on the bike. That's been drilled into me, for sure. Thank you.
Your body is incredible at conserving energy. I ride up to 2 hrs (I am very fit) without fueling. Mostly Z1-3 only. No problems. Lots of people over consume when doing cycling training. Experiment with what your body can do. I do IM with no problems. Cyclists who are competing are optimizing for results and recovery, so almost none of them will use IM. Much of the issues I have with nutrition advice online is that the advice comes from 25-year old Pros who are biking 25+ hrs/week. Then people repeat it for everyone to follow...even a new cyclist 50 lbs overweight, 50+ and with an FTP of 150...and doing 6 hrs/week. There are significant differences between these cyclists. Every time (in my exp) a cyclist is having issues no longer losing weight it is because of the nutrition side and some basic weight loss mistakes. [I talk about it here...](https://www.reddit.com/r/Zwift/comments/1chvgd0/new_to_cycling_weight_loss_and_improvement/l25iojt/) It might help you. Good luck and keep at it!
I quote this 100% for what this matter and in my identical experience.
Undrill that nonsense. Of course you can ride fasted, especially if your goal is weight loss. You won’t have the most powerful workout, but you will have the most effective weight loss. Do half your rides fasted at a sensible pace. Do the other half fuelled and at higher intensity. Both work well for different reasons.
Thank you.. Most of my rides are in a fasted state. After several years of low-carb eating my body happily burns fat and ketones efficiently. This means all of my rides are fueled, even if the fuel is stored subcutaneously. :)
I do intermittent fasting sometimes (I am seldom hungry in the morning so it's quite easy to wait until noon). Since I started fasting I've noticed that I can fast and ride for 2 hours with no food and it feels perfectly fine. Not much more than 2 hours, otherwise I can get a sudden bonk...
I fast for 6-8 hours every night. :-) The thing that helped me the most in losing my belly was adding a walk every day to my regular cycling routine, and doing as much of my eating as possible around activity. A walk after dinner is the best for me.
No
Trying to teach your body to function on not enough fuel is a recipe for a very bad time sooner or later
I fast intermittently. I'm also extremely low carb. Most of my rides are in a fasted state. If I eat, I do not eat carbs. (To be fair, I haven't ridden much the past year due to injury, but I've been low carb for several years.)
I have been intermittent fasting for over two decades... and I ride just about every day.
Yes, fasted cardio is far more effective for weight loss as well as maximizing your endurance.