Is riding when fasting a bad idea?
 

I'm generally not hungry when I wake up and often start my commute (45-60 mins) on an empty stomach. I have a whey protein shake when I get to work, and it's normally enough to keep me going until lunchtime.

I was wondering whether it's a bad idea to cycle at moderate intensity (avg 140bpm heart rate) when fasted (possibly burning muscle), or whether a 45 minute ride is still using glycogen reserves in the blood?

Would I ride better having a small about of carbs first thing in the morning?

Thanks!

John.

I do fasted rides of up to 2 hours 3-4 times a month, with no limitations on intensity, and no perceived ill effects. But I think this comes down to reserves-- I'm north of 200lbs, and seldom even feel hungry on the bike until I've passed 2,000kJ of output, so 50 miles @ 70% intensity on nothing but water is fairly routine for me. My guess though is that at just 45 minutes, you're not getting even partially through your glycogen reserves, unless you're one of those skinny folk.

I do hard 1.5-2 hour workouts fasted all the time, I only really eat before a race or if I'm planning on riding 3+ hours.

It takes a little bit of training to be able to do the intense stuff fasted but moderate activity for 45 min is no problem. There's even a good rationale behind doing this, I would argue that it's preferable for you to do your morning commute fasted.

I did a 35 km commute once in a while a few years ago, and I'd usually do it on an empty stomach ... maybe a small glass of orange juice if I did feel a bit hungry. It was all right. :)

You should be fine riding fasted like that, and yes, you probably have enough glycogen stored up that it's no problem (as in, no concern with muscle loss). I'm the same way when it comes to [not] being hungry in the morning.

I often recommend that people try starting their morning rides in a fasted state, because more often than not, they're struggling to get up early enough to eat early enough beforehand that they don't feel sluggish during the ride.

A normal, healthy human has enough reserves for over two hours or so, even at pretty high intensity. That may not be true for water, but even that is possible except in hot humid climates.

So, a one hour commute, even at high effort shouldn't be an issue. However you can let your own body tell you, and adjust accordingly.

No, there's nothing wrong with what you do. A lot of cyclists find it's easier to ride on an empty or empty-ish stomach than with heavy food in there. On weekends and vacations I don't want to wait for breakfast before I start riding.

Muscle is a really inefficient source of energy. A well trained male has about 2,500 kCal of glycogen stored and ready to go, and a virtually unlimited supply of fat even when it doesn't look that way.

If you're concerned about preserving muscle: do strength training, make sure you get adequate protein.

No, it's not a bad idea. You are training your body to burn fat. When I'm doing a lot of sweet spot training, I will typically do them as part of the morning commute on just a cup of black coffee. I put a bar in my jersey pocket in case I feel bonkish, but it's never been a problem.

It's fine, and you might even find that your digestive system works better with a longer overnight break from digesting.

After researching different types of fasting, I thought I'd try restricting my feeding to between 11am and 6pm.

Morning commutes and weekend rides have been fine on coffee and water.

https://nyti.ms/2q4OaXR

interesting read in todays NYT suggesting that you might be better off not eating and relying on reserves.

Thanks for the link. The consensus seems to be that you can do quite a lot of exercise on an empty stomach, assuming you have a normal amount of stored carbohydrate (glycogen?) from your last meal. Probably burning 2000-2500 calories is the limit for most adults, which is likely to be at least 1.5-2 hours' fairly hard riding.

I do feel quite hungry after my morning commute, but not ravenous. I normally just have a whey protein shake to beef up my carb & protein levels, and I'm good until mid-day.

I try to listen to my body, but avoid binge eating after a ride and pace my food intake even if feel very hungry.

Thanks for all the answers!

John

It also doesn't have to be either/or. A piece of toast or a banana on the way out the door is an option that works well for me.

Every Saturday morning I do a club ride with a fast B group that at times, often is faster than the A group. I suffer from some weird sort of digestive disorder that was never diagnosed but if I eat before a hard workout, I get stomach cramps, diarrhea and painful discomfort..... so I don't eat before I ride.
I do drink 2 regular cups of coffee, some supplements like B12 and off I go at a pace of 19-20 mph in 42 miles while climbing 3000 ft.
Sometimes, I wake up tired and not ready for a fast ride, so I drink a Ketosis type of drink that makes my body pull energy from fat rather than glucose, and it works.
So, riding depleted and fasted might not harm you, hurt you and actually help you if you want to lose weight or have digestive issues like me.
I never figured out what is wrong, but I did figure out how to avoid it.

My muslim friend/cyclist who's fastign rides 1 hr before he eats in the evening. Seems to be doing well.

Riding while actually fasting ("bonked") is not much fun. It's like riding with a 50lb sack of sand strapped on your back. It is however doable. Don't expect to go very fast. You do get used to it after a while. I don't mind hiking in full keto, but with cycling it's kind of a bummer. Caffeine helps a little (in moderation please).

Skipping breakfast (or other meal) before a ride is not the same thing as fasting. Unless you skipped dinner the night before, you will have glycogen in your body to burn. I rarely eat breakfast unless I know I will ride over ~50 miles. I will still have enough fuel not to bonk for 3+ hours, as long as I ate some pasta, rice or whatever for dinner the night before the ride.

I've been doing my morning commute (10mi) fasted for almost 3 years, no problems. I have breakfast when I get to work.

The only thing I've noticed is that on my morning ride I'm usually slower than on my ride home in the evening xD

I also have been trying to ride on just coffee in the morning, usually a 15 mile commute with ~5-600ft of climbing. Seems be helping shed weight, ~7lbs in 3 months without much other changes to the diet, but a lot more riding so hard to pinpoint the exact relationship.

Most people have around 1000cal of readily stored energy, and you're probably somewhere in that range.

If you're not having a significant performance drop on the tail of your ride then you're fine. If you get to work feeling tired, and feel better immediately after eating, that's a sign you should probably eat something light before starting.

I think you're defining fasted differently than most. I don't think anyone is suggested riding in a totally glycogen depleted state, which is how I understand bonking.

Yeah, it would seem that way. Semantics I guess. To me fasting means going at least a full day with no food.

Skipping breakfast before a ride? = no big deal. Make sure you eat some carbs the night before.

Sounds like this isn't a problem for you at all.

What issues there are with riding fasted are more psychological than physical (which doesn't mean they aren't real, as the brain will act to limit intensity under certain conditions). If you're used to it, it really isn't a problem at all (and if you weren't used to it, you would get used to it fairly quickly). As others have said, you have more than enough energy reserves to go for a long time.

Since I've been IFing (no food until 5pm + avoiding carbs amap) for four (?) years I'll give you first person experience. Being a fat burner is healthy, but it is not at all ideal for 'competitive' athletic performance. I can run a half marathon with little problem/no training, but eight minute miles are the thing of the past. My personal experience is you lose the ability to source and maintain maximum energy output, like explosive speed and strength. Bad for weight lifting, bad for sprints. Sort of like trying to light a wood fire with a match compared to lighting off paper.

If I was into racing, I would train with carbs & frequent meals. Reality, I'll bike and run with no food whatsoever before but cups of coffee/water, maybe a glyc/protein boost afterwards to aid recovery. Once your body is acclimated (months) it is very natural.

This is a very good point. For maximum performance (or a more demanding ride) I would pay much more attention to nutrition and taking in a sufficient selection of carbs before and during the ride.

The state of fasting is defined generally as having digested and processed all fuel. This is accomplished overnight. Riding fasted in cycling terms simply means no supplemental carb consumption forcing the body to use stored glycogen and fat, which varies by percentage depending on intensity. Intermediate fasting for cycling is a well documented way to increase fat burning capability at aerobic level efforts with training by increasing mitochondrial cell content

@OP

Its depend what is your goal, you can't have the best of both world, its trading off

If you're elite athlete/racer, you better go train with carbs load but if you just want to shred some dead weights, its good idea to do IF training

Just beware of nutrition timing, eat good, eat right and eat enough to stay within calories deficit

P.S. I am IF rider as well, trying to shred couple pounds atm, its slow but good progress