You’ve nailed the training. You’ve logged the hours. But somewhere around the 60 km mark, everything falls apart. Legs turn heavy. Energy disappears. The group pulls ahead.
The reality? You’re probably burning the wrong fuel.
Your body has two primary energy sources: carbohydrates and fat. Carbs burn fast. Fat burns steady. Many cyclists fuel in a way that locks them into carb dependency, leading to constant top-ups, sugar crashes, and the dreaded bonk when the tank runs dry.
These five mistakes may be keeping you stuck in that cycle.
Mistake #1: Training Your Body to Only Burn Sugar
The mistake:
Fueling every ride with high-sugar gels and drinks teaches your body to expect quick-burning fuel, reducing its ability to tap into fat stores.
Why it costs you watts:
Fat provides nine calories per gram versus four from carbohydrates. Your body stores thousands of calories as fat but only limited glycogen. Relying only on carbs means operating from a relatively small tank that empties quickly.
The fix:
Include easier aerobic rides with minimal carbohydrate intake. Focus on low-GI, slow-release fuels that avoid sharp blood sugar spikes. This helps train your body to access fat stores more efficiently.
Mistake #2: Extreme Eating — Swinging Too Far to One Side
The mistake:
In the pursuit of getting lean or “eating clean,” athletes often swing to extremes — either very high carb and very low fat, or high fat and very low carb. Both approaches can undermine performance.
Why it costs you watts:
Endurance performance depends on a balance between carbohydrate and fat metabolism. Think of your body like a hybrid engine:
- Carbs = high-intensity rocket fuel
- Fats = long-haul endurance diesel
Cut carbs too aggressively and you may struggle when intensity rises. Eliminate fats and you blunt your ability to burn fat efficiently, increasing reliance on limited glycogen stores.
The fix:
Adopt a balanced, athlete-friendly nutrition strategy:
- Include healthy fats daily (olive oil, avocado, nuts, seeds, fatty fish)
- Consider medium-chain triglycerides (MCT oil) where appropriate
- Prioritise complex carbohydrates such as whole grains, leafy greens, root vegetables, and nutrient-dense fruits
This supports metabolic flexibility — the ability to efficiently use both carbs and fat.
Mistake #3: Ignoring Your Gut During Long Rides
The mistake:
Focusing only on what you consume while ignoring how well you absorb it.
Why it costs you watts:
High-sugar fuels can cause bloating, nausea, and gastric distress, especially at higher intensities. If your gut shuts down, nutrients aren’t absorbed and performance drops quickly.
The fix:
Train your gut just like you train your legs:
- Practice race nutrition in training
- Test different fuel types
- Mix fuel sources if needed
- Ensure adequate electrolytes to support absorption
Every rider’s tolerance is different — find what works for you.
Mistake #4: Forgetting Electrolytes and Hydration Timing
The mistake:
Focusing on calories while neglecting sodium, potassium, and magnesium — or over-drinking plain water.
Why it costs you watts:
Electrolytes are essential for muscle contraction and nutrient absorption. Without adequate sodium, your body cannot efficiently utilise the carbohydrates you consume. Overhydration without electrolytes can also be dangerous.
The fix:
Hydrate strategically, not just frequently.
- Match sodium intake to your sweat rate
- In hot conditions or long efforts, aim for roughly 300–1000 mg sodium per hour
- Test different electrolyte strengths during training
Mistake #5: Using the Same Strategy for Every Ride
The mistake:
Fueling every ride the same way — whether it’s an easy spin or high-intensity intervals.
Why it costs you watts:
At low intensities, your body can comfortably burn fat. At higher intensities, it needs readily available carbohydrates. Mismatching fuel to effort compromises both fat adaptation and peak performance.
The fix:
- Easy aerobic rides (<70% max HR): keep carbs lower and allow fat utilisation
- Tempo and high-intensity rides: introduce carbohydrates early and consistently
This builds metabolic flexibility and supports sustained power output.
The Bottom Line
You’re not broken. You’re not slow. Often, the issue is simply using the wrong fuel at the wrong time.
Fat is a powerful, abundant energy source — but accessing it requires the right mix of training, nutrition habits, and fuelling strategy. Address these five common mistakes and you can unlock more stable energy, fewer crashes, and stronger performance deep into your rides.