Fasted running

I'm an experiment of one, but I do ALL of my running in a fasted state. I've done 90+ mile weeks with 22 mile long runs in a fasted state. I didn't bonk, lose muscle mass or anything else. It works just fine for me. You'll just have to try it and see.

I'm an experiment of one, but I do ALL of my running in a fasted state. I've done 90+ mile weeks with 22 mile long runs in a fasted state. I didn't bonk, lose muscle mass or anything else. It works just fine for me. You'll just have to try it and see.

Me too. Except the 90+ mile weeks. Never done those!

Oh, and I have breakfast three hours before a race. And occasionally I have to run in the evening, in which case I have a mid-afternoon snack. But otherwise I just do all my runs - long, short, fast, whatever - before breakfast. Otherwise I'd have to get up WAY earlier than I'd like.

Fasted LISS? Sounds like a recipe for muscle loss and high cortisol levels.

If your goals are centered around running then eat a healthy meal an hour or so before you run. If your goals are centered around body composition then eat a meal an hour before you train and stop running. Instead, lift weights and do HIIT. I would recommend a heavy bag, prowler, sledge hammer, kettlebell or a heavy carrying implement (this could just be a big rock) for your HIIT.

OK! Here is my skinny on fasted and unfasted running.

First some fueling tips if you do decide to eat before running.

Try different things. Different people react to different foods differently. You want to experiment in training runs so you know what works and doesn't work as you prepare for races. When you find something that works, you gonna want to replicate that before a race. This includes your day before pre-race meal.

Eating too many calories before a run can lock up your stomach pretty bad and cause discomfort. As you run, blood is being diverted to the areas that require oxygen and liver glycogen and fat absorption during your run. This blood is diverted away from other functions such as digestion. I go by Runner's World Big Book of Marathon and HM Training. 600 calories approx 3 hours before a big run in simple carbs or 200 cals 1 hour before. As you are running, 100 cals 30 minutes into the run and 45 minutes thereafter.

Why fuel up as you are running? As your body uses the anaerobic system (burning fuel without the presense of oxygen) you will be burning up your internal carb stores (glycogen). You have a limited supply. Different people have different levels and it depends how intense you run, but for most experienced runners, they should be able to run 15-20 miles and even beyond without worry of bonking (clearing out their glycogen supply). Running way beyond your aerobic threshold or poor training may cause you to bonk much sooner. The idea is to supplement the amount of glycogen you use up as you run but not replace it all together during the run. If you bonk too fast, then you are running faster than you should for your goal distance.

If you run at a pace that is below your aerobic threshold (burning fuel in the presense of oxygen) then your fuel supply relies more on your internal fat storage as opposed to glycogen. Your body (in comparison to gycogen) has a virtual endless supply of fat to fuel long term activity.

So this leads us into training and especially fasted training.

If you have long steady training runs that you rely on your aerobic system, your body will begin to learn to rely more on fat burning as opposed to glycogen burning. Training fasted during these runs will slowly deplete your glycogen and will stimulate growth in this area. In other words, your body will soon learn to store more glycogen for future runs. As you sleep, your body begins to use up and lower your blood sugar. When your blood sugar goes below a certain point, it may either use fat or glycogen to fuel your bodies survival mechanisms as you sleep. If you train to rely on fat burning, your body will burn less glycogen but it will burn some glycogen none the less. So unless you eat something in the morning before you run, you will have diminished glycogen stores.

This could be a good thing tho if you don't mind diminished performace in trade for stimulating growth.
At a certain point, your body will experience diminished returns and poor performance will outweigh the benefits of stimulating the growth of glycogen storage. But in the beginning of the training season, the diminished supply of blood sugar and glycogen during fasted runs will take some getting used to as your body learns to power from your fat storage and aerobic system.

If fasted running causes the body to learn to store more glycogen, it will become increasingly difficult to do fasted running, n'est-ce pas? ????

I have actually read some conflicting physiology studies on this. Running (in general) especially in a fasted state burns more fat during exercise than other forms of exercise which up regulates production of fat mobilizing enzymes. This could be a good thing DURING your run; however, after the run the upregulation of these enzymes can make it easier for you to store fat. Whereas, stimulation of glycogen mobilizing enzymes would be best performed with anaerobic methods of training.

OK! Here is my skinny on fasted and unfasted running.

First some fueling tips if you do decide to eat before running.

Try different things. Different people react to different foods differently. You want to experiment in training runs so you know what works and doesn't work as you prepare for races. When you find something that works, you gonna want to replicate that before a race. This includes your day before pre-race meal.

Eating too many calories before a run can lock up your stomach pretty bad and cause discomfort. As you run, blood is being diverted to the areas that require oxygen and liver glycogen and fat absorption during your run. This blood is diverted away from other functions such as digestion. I go by Runner's World Big Book of Marathon and HM Training. 600 calories approx 3 hours before a big run in simple carbs or 200 cals 1 hour before. As you are running, 100 cals 30 minutes into the run and 45 minutes thereafter.

Why fuel up as you are running? As your body uses the anaerobic system (burning fuel without the presense of oxygen) you will be burning up your internal carb stores (glycogen). You have a limited supply. Different people have different levels and it depends how intense you run, but for most experienced runners, they should be able to run 15-20 miles and even beyond without worry of bonking (clearing out their glycogen supply). Running way beyond your aerobic threshold or poor training may cause you to bonk much sooner. The idea is to supplement the amount of glycogen you use up as you run but not replace it all together during the run. If you bonk too fast, then you are running faster than you should for your goal distance.

If you run at a pace that is below your aerobic threshold (burning fuel in the presense of oxygen) then your fuel supply relies more on your internal fat storage as opposed to glycogen. Your body (in comparison to gycogen) has a virtual endless supply of fat to fuel long term activity.

So this leads us into training and especially fasted training.

If you have long steady training runs that you rely on your aerobic system, your body will begin to learn to rely more on fat burning as opposed to glycogen burning. Training fasted during these runs will slowly deplete your glycogen and will stimulate growth in this area. In other words, your body will soon learn to store more glycogen for future runs. As you sleep, your body begins to use up and lower your blood sugar. When your blood sugar goes below a certain point, it may either use fat or glycogen to fuel your bodies survival mechanisms as you sleep. If you train to rely on fat burning, your body will burn less glycogen but it will burn some glycogen none the less. So unless you eat something in the morning before you run, you will have diminished glycogen stores.

This could be a good thing tho if you don't mind diminished performace in trade for stimulating growth.
At a certain point, your body will experience diminished returns and poor performance will outweigh the benefits of stimulating the growth of glycogen storage. But in the beginning of the training season, the diminished supply of blood sugar and glycogen during fasted runs will take some getting used to as your body learns to power from your fat storage and aerobic system.

If fasted running causes the body to learn to store more glycogen, it will become increasingly difficult to do fasted running, n'est-ce pas? ????

I have actually read some conflicting physiology studies on this. Running (in general) especially in a fasted state burns more fat during exercise than other forms of exercise which up regulates production of fat mobilizing enzymes. This could be a good thing DURING your run; however, after the run the upregulation of these enzymes can make it easier for you to store fat. Whereas, stimulation of glycogen mobilizing enzymes would be best performed with anaerobic methods of training.

The whole point of training, esp endurance running, is to train the body to optimally perform under certain specific conditions. Endurance training effects are meant to improve endurance performance--sometimes that does not coincide with other exercise goals such as weight loss or even overall health. Overall, the idea of doing fasted cardio for fat loss has been shown to be seriously flawed, if not outright debunked--but that's a different topic

Glycogen sparing is obviously a good thing for endurance performance.

Another point: a number of studies have shown that HIIT training can result in some of the same fat-burning adaptations as endurance training.This has lead to some people again trying to assert that HIIT training is a "one stop shop" that obviates the need for endurance training. However, every instinct of training and physiology says that you cannot train for a marathon by doing 20-min max interval training workouts, so I am looking forward to further research on this topic.

I agree that HIIT wouldn't be appropriate for a competitive long distance runner to focus a majority of their time on. The SAID principle always applies to sports specific training.

OK! Here is my skinny on fasted and unfasted running.

First some fueling tips if you do decide to eat before running.

Try different things. Different people react to different foods differently. You want to experiment in training runs so you know what works and doesn't work as you prepare for races. When you find something that works, you gonna want to replicate that before a race. This includes your day before pre-race meal.

Eating too many calories before a run can lock up your stomach pretty bad and cause discomfort. As you run, blood is being diverted to the areas that require oxygen and liver glycogen and fat absorption during your run. This blood is diverted away from other functions such as digestion. I go by Runner's World Big Book of Marathon and HM Training. 600 calories approx 3 hours before a big run in simple carbs or 200 cals 1 hour before. As you are running, 100 cals 30 minutes into the run and 45 minutes thereafter.

Why fuel up as you are running? As your body uses the anaerobic system (burning fuel without the presense of oxygen) you will be burning up your internal carb stores (glycogen). You have a limited supply. Different people have different levels and it depends how intense you run, but for most experienced runners, they should be able to run 15-20 miles and even beyond without worry of bonking (clearing out their glycogen supply). Running way beyond your aerobic threshold or poor training may cause you to bonk much sooner. The idea is to supplement the amount of glycogen you use up as you run but not replace it all together during the run. If you bonk too fast, then you are running faster than you should for your goal distance.

If you run at a pace that is below your aerobic threshold (burning fuel in the presense of oxygen) then your fuel supply relies more on your internal fat storage as opposed to glycogen. Your body (in comparison to gycogen) has a virtual endless supply of fat to fuel long term activity.

So this leads us into training and especially fasted training.

If you have long steady training runs that you rely on your aerobic system, your body will begin to learn to rely more on fat burning as opposed to glycogen burning. Training fasted during these runs will slowly deplete your glycogen and will stimulate growth in this area. In other words, your body will soon learn to store more glycogen for future runs. As you sleep, your body begins to use up and lower your blood sugar. When your blood sugar goes below a certain point, it may either use fat or glycogen to fuel your bodies survival mechanisms as you sleep. If you train to rely on fat burning, your body will burn less glycogen but it will burn some glycogen none the less. So unless you eat something in the morning before you run, you will have diminished glycogen stores.

This could be a good thing tho if you don't mind diminished performace in trade for stimulating growth.
At a certain point, your body will experience diminished returns and poor performance will outweigh the benefits of stimulating the growth of glycogen storage. But in the beginning of the training season, the diminished supply of blood sugar and glycogen during fasted runs will take some getting used to as your body learns to power from your fat storage and aerobic system.

If fasted running causes the body to learn to store more glycogen, it will become increasingly difficult to do fasted running, n'est-ce pas? ????

I have actually read some conflicting physiology studies on this. Running (in general) especially in a fasted state burns more fat during exercise than other forms of exercise which up regulates production of fat mobilizing enzymes. This could be a good thing DURING your run; however, after the run the upregulation of these enzymes can make it easier for you to store fat. Whereas, stimulation of glycogen mobilizing enzymes would be best performed with anaerobic methods of training.

The whole point of training, esp endurance running, is to train the body to optimally perform under certain specific conditions. Endurance training effects are meant to improve endurance performance--sometimes that does not coincide with other exercise goals such as weight loss or even overall health. Overall, the idea of doing fasted cardio for fat loss has been shown to be seriously flawed, if not outright debunked--but that's a different topic

Glycogen sparing is obviously a good thing for endurance performance.

Another point: a number of studies have shown that HIIT training can result in some of the same fat-burning adaptations as endurance training.This has lead to some people again trying to assert that HIIT training is a "one stop shop" that obviates the need for endurance training. However, every instinct of training and physiology says that you cannot train for a marathon by doing 20-min max interval training workouts, so I am looking forward to further research on this topic.

I agree that HIIT wouldn't be appropriate for a competitive long distance runner to focus a majority of their time on. The SAID principle always applies to sports specific training.