Fueling your indoor cycling: Science-based tips for crushing the calories

Most cyclists are now making indoor riding an integral part of their weekly training. They have their pain cave set up with a quality smart bike or smart trainer. They have fans and towels at the ready. Their screens and earphones are within easy reach. But there’s one thing missing…

While most of us head out for outside rides with jersey pockets stuffed with gels, bars and bananas, there’s a tendency for riders to forget to pay the same attention to nutrition when riding indoors. Maybe it’s because we tend to prefer to do those shorter 45-minute to 2-hour rides indoors; or that we can simply jump off the bike and quickly grab a snack from the kitchen if we feel hunger rear its head. 

But fueling is just as important for indoor riding as it is for riding on the road or trail. In fact, given that many of us do high intensity intervals or energy-sapping sweet spot work indoors, it’s potentially even more essential we fuel our bodies properly for these workouts. In this post, we’ll explore the science behind fueling your indoor cycling workouts for optimal performance and recovery.

Why you need to fuel your rides

Before delving into specific nutrients and numbers, let’s take a helicopter view of the body’s caloric needs. First, there’s your daily caloric expenditure. Based on your resting metabolic rate (RMR), this is the baseline number of calories you need to keep you, your brain and your body functioning. Factors such as age, sex, and lean body mass influence your RMR, and it fluctuates over time.

Any significant activities, such as cycling, create additional calorie demands on top of that daily requirement. If you consume fewer calories than you “burn” due to your daily need and the demands of your cycling, then you’ll be in a caloric deficit. That’s how you lose weight, for example, which sounds like a good thing, right? 

However, if that deficit is too significant, or continues too long, you won’t only lose weight. You’ll lose lean muscle mass, you’ll hamper your body’s ability to recover, your sleep quality is likely to suffer and your hormonal balance will take a hit. None of which screams optimal cycling training. The impact can be even more severe for female cyclists.

Now let’s zoom in a little and look at a single session. If you go into your ride fully fueled, you’ll have roughly 90 to 100 grams of carbohydrate available as glycogen stored in the liver, with a further 25 grams of glucose in the blood. That’s enough to fuel roughly 90 minutes to two hours of steady exercise.

At that point, your body will turn to alternative fuel sources, such as fat stores. But the body is less efficient at turning fat into available energy, especially at higher intensities. Which is why, as marathon runners and cyclists know only too well, you will “hit the wall” or experience a “bonk” or “hunger knock” if you don’t fuel your activity.

So, does that mean you don’t need to fuel sessions of less than 90 minutes?

In theory, maybe. However, the reality is that due to our busy lives, the chances are you’re not starting every indoor ride with your glycogen levels at 100%. Plus, many of the interval sessions we do on the indoor trainer are extremely high intensity, which causes your body to burn at a higher rate so you’ll work through those stores faster.

Plus, the reality is that continually running down those stores is stressful for your body and results in sub-optimal training. Fueling your sessions, even shorter ones, will improve the quality of the workout itself, but will also improve your recovery, meaning you start your next session better set for success.

How should you fuel?

There’s a lot of conflicting advice about fueling and the science backs up multiple different schools of thought, suggesting there’s no single perfect way to fuel and that each cyclist needs to find what works best for them. However, certain principles are universally true.

Carbohydrates are the primary fuel source

Carbohydrates serve as your body’s preferred source of fuel during cycling. As we’ve already established, glycogen stores within the liver and muscles provide energy for approximately 90 minutes of exercise, so, to sustain longer rides, we need to replenish carbohydrates regularly. 

Most research has traditionally suggested consuming between 30g-60g of carbohydrates per hour. However, we can increase that to 90g by using a mix of glucose and fructose in a 2:1 ratio. 

Again, it’s important that we don’t finish rides completely depleted or carbohydrates. Research suggests that, to maximize recovery and increase our capacity to perform well in upcoming workouts, we should ingesting at least 1.2 g carbohydrate per kilogram body mass per hour for a couple of hours after hard sessions.

Look at the diets of elite cyclists, marathon runners and triathletes and you’ll notice that they’re almost all carb-eating machines. While we shouldn’t seem to emulate their diets – professional endurance athletes often train 30-40 hours per week meaning that their fuel demands are enormous and that they’re also able to oxidize fat due to sheer volume of training – what we can learn from them is that carbs are essential for performance.

Protein for recovery and repair

Indoor bike sessions tax your aerobic system and also induce muscle breakdown. It’s by the body repairing and super-compensating (i.e. building back stronger) that your legs become more powerful and able to push higher watts for longer.

Protein plays a vital role in muscle repair, so adequate protein intake is essential to support repair and adaptation. Recommendations vary based on ride intensity, with suggested intake ranging from 1.2g-2.2g of protein per kilogram of body weight. 

You don’t need to take on protein when on the bike, or even chug down a huge volume after a ride. Studies show that spreading protein intake throughout the day optimizes absorption and utilization, and, for optimal benefits, you should try to avoid consuming large amounts of protein (more than 200g) in a single sitting.

Vitamin D for performance and recovery

Vitamin D plays a crucial role in general health, but even more so for endurance athletes. Research shows that increasing our levels of vitamin D can reduce inflammation and pain while increasing muscle protein synthesis, strength, explosiveness and our capacity for exercise. All of which is pretty important for cyclists!

Those of us who love the benefits of indoor cycling may need to top up our levels, given that sunlight is a source of Vitamin D, but even cyclists who ride outside all the time will likely have to top up their levels with supplemental vitamin D3 to reach the necessary levels.

Making it simple

All of this advice can feel overwhelming, so we’ll provide some general rules of thumb to make it easier for you.


  • Eat a nutrient-rich diet with plenty of protein and make sure you have a wide range of colors on your plate.
  • Supplement with 1000-5000 IU of vitamin D3 per day for improved performance and recovery.
  • Have a full glass of water with each of your meals, and sip throughout the rest of the day.


  • For easy recovery rides of 30-60 minutes in length, just eat well at meal times around your ride but you don’t need any supplemental carbs for your ride.
  • For base or long easy rides, aim for 30-60g carbs per hour, aiming for the higher end of this range for rides of 3 hours or more.
  • For intense interval type sessions, aim for 60-80g per hour. This can be in the form of gels or carb drinks, but try to sip steadily throughout your workout; research shows that even the taste of sugars in the mouth can improve feel and performance.
  • Drink at least 500g of water with electrolytes power hour. The electrolytes are especially important for riding indoors, where you’ll often sweat heavier.
  • Consume a carb-protein mix within 10 minutes of stepping off the bike. For simplicity, we like a dedicated recovery shake or even chocolate milk.
  • Eat your next meal within 1-2 hours of completing your workout.

Fuel your indoor cycling sessions with the right nutrients and you’ll maximize your performance, promote recovery, and significantly improve your chances of achieving your cycling  goals. Yes, there’s a lot of information out there and it can sometimes become overwhelming but by boiling it all down to the basics and following the science, you can set yourself up for indoor cycling success.