If you want to lose weight to get faster on the bike, training when your body is in a low glycemic state is one of the most beneficial habits you can implement into your daily or weekly schedule. This practice is known as fasted training.

What if you could re-engineer your body to function at its peak and burn fat more efficiently by simply tweaking what you consume before a workout? That might sound like an opening line straight out of an infomercial selling a “miracle” weight loss pill, but that’s the science-backed promise of fasted training.

What is Fasted Training?

Fasted cycling training is completing a workout in a low glycemic state and not consuming any carbohydrates beforehand. Typically only water or coffee is taken in before or during. Fasted rides are low-intensity and usually less than one hour.

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The big goal of fasted training is to increase your body’s ability to metabolize fat by denying your body of glycogen. The aerobic energy system uses both glycogen and fat as fuel. Training in a low glycemic state signals the body to use fat. 

For this to happen, you will have to intervene by restricting carbohydrates for some time. Without intervention, your body will not be forced to adapt. As a result, it will seek out sugar (the fuel source it likes best) to feed on during your workout.

What Happens When You Ride in a Fasted State?

When intervention does occur, your body is able to gradually replace glycogen consumption with fat consumption during your workout. This is how all that fat-burning magic happens.

If that’s not impressive enough, fasted cycling training also teaches your body how to improve its metabolism when you’re in a rested state. So while many athletes go into fasted training with the sheer desire to lose fat, what they might not fully realize is how in the process, they’re making their bodies better at metabolizing fat across the board—that’s metabolic training in a nutshell!

How quickly this transformation happens is subjective, and based on the degree you’ve damaged your metabolism in the past. The metabolism of a person who’s been replacing sugary beverages with water for years, for instance, will adapt more quickly than that of someone who recently gave up heavy soda drinking.

Caffeine’s Role in Fasted Training

It’s common for athletes who use fasted training to drink coffee just before the workout. This is a good idea because, as we all know, caffeine encourages fat metabolism. The trouble is, all coffee, better yet, all coffee creamers are not created equal. In fact, most will reverse the effects of fasted training.

If you’re a coffee drinker who wants to get into fasted training, your only safe creamer option is heavy whipping cream. With heavy whipping cream, we’re talking pure fat — no sugar or lactose. That’s the key.

Even though there’s not a ton of sugar in something like half and half or low-sugar coffee creamers, there’s still some, which will disrupt the entire fasting process if you consume it. Why? Because you’ve just introduced glycogen into the mix.

Your body doesn’t care how little of an amount it may have been. It’s like a shark with blood. The second your body gets a taste of glycogen, it will go for it and leave anything else that might have been desirable to consume for fuel behind. Then comes the most unfortunate part of all: your fat metabolism shuts down. This is what you want to avoid.

If you’re not a coffee drinker and you still want to reap the boosting effects of caffeine, consider taking a caffeine pill 15-30 minutes prior to your workout.

Two Ways Cyclists Can Implement Fasted Training

There are two manageable and smart ways you can implement fasted training into your routine. The first involves doing your workouts earlier in the day after you’ve had a night of rest and before you’ve had anything to eat. The second way to implement fasted cycling training involves two-a-days.

When Should I include Fasted Training?

Early morning workouts are typical for those who do fasted training. After 12+ hours of not consuming any carbohydrates, most people’s liver stores are depleted, and their muscle stores have just enough glycogen in them to get the person through a 60-90 minute workout. This is one of the reasons TrainerRoad’s workouts and structured training plans work well with fasted training —they’re all about that duration.

The second way you can implement fasted training into your routine is by doing two-a-days, i.e., completing two workouts in a 24-hour timeframe. If you’re the type of athlete who feels like they can’t get their best high-intensity workouts done in the mornings, this is probably your best option. I know it is for me. 

In the mornings, again before you’ve had anything to eat except for maybe a cup of black coffee, do a soft-pedal workout for about 30 minutes — we recommend the workout Dans for this — to reap the benefits of fasted training. Then, in the afternoons or evenings, complete your higher intensity workouts. If two-a-days sound like something you might like, start by giving it a try three times a week right out of bed and see how you feel.

How Long Should My Fasted Ride Be?

If you plan on doing a workout that’s more than 60-90 minutes and you’re going into it fasted, be warned. You are probably going to start breaking down muscle. During a workout, it takes about 60-90 minutes to exhaust your glycogen stores. 

Once your muscle stores are deficient in glycogen, you can expect to hit a wall in your workout unless your intensity stays relatively low. How soon until that fatigued feeling consumes you will depend on the intensity of your workout. Because lower intensity workouts require less and sometimes very little glycogen, you’ll likely be able to last well past that 60-90 minute period without introducing fuel on the bike.

Be very mindful of how you’re feeling, and don’t be afraid to bail out of your workout if you need or introduce some quick-digesting carbohydrate into the mix. Something like a sports drink or even a gel washed down with plenty of water should do the trick. One way to tell you’ve crossed that line is the smell of ammonia on your breath.

The Best Cycling Workouts for Fasted Training

Since depletion occurs naturally after a 60-90 minute workout, I do not advocate doing high-intensity training in a depleted state. Depletion should come before low-intensity work or after high-intensity work—but not before high-intensity work. High-intensity work absolutely needs to be fueled if you want to reap the maximum benefit from your workout—you can’t do that in a glycogen depleted state.

Dans is an active recovery cycling workout and is a good starting point for fasted training.

A good idea is to start slow when adding fasted rides to your training. You can give it a try by adding Dans to your calendar. Dans is a shorter active recovery ride. Once you feel comfortable, you can increase the duration, but keep the intensity low with Lazy Mountain

Pros and Cons of Fasted Rides

We’ve gone over most of the positives of fasted training. Increased fat metabolization can help you lose weight, improve body composition, and reduce your reliance on carbohydrates during low-intensity rides. However, some negatives come along with the benefits. 

Fasted training increases the stress on your body, especially as the intensity ratchets upward. This can overwhelm your ability to recover fully, which will compromise the quality of future workouts. This is why it’s a good idea to start slow and limit fasted rides to 2-3 per week.

Final Words

While fasted training might not be as easy as taking a “miracle” diet pill to lose weight, it’s surely effective. When you practice fasted training, not only will your body burn more fat during your workouts, it’ll also become programmed to favor fat as its fuel source even when you’re off the bike. But just like any other training tool, fasted training has its place and should be used only when the time is right.

For more answers to your cycling training questions, listen to Ask a Cycling Coach — the only podcast dedicated to making you a faster cyclist. New episodes are released weekly.

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Chad Timmerman

Chad Timmerman is the Head Coach and Co-Founder of TrainerRoad — cycling’s most effective training system. He has nearly 10 years of coaching experience as a Level I USA certified Cycling and Triathlon coach. When he’s not developing structured training plans for TrainerRoad, you can catch him sharing his coaching advice on the Ask a Cycling Coach podcast. To get Chad’s best cycling knowledge delivered to your inbox, sign up for our email list.