Nutritional Periodisation: Why You Should Eat Differently in Different Parts of Your Season

Most cyclists eat more or less the same things year-round and adjust portions slightly based on how much they are training. That approach works reasonably well. But it is not optimal, and the gap between reasonable and optimal is wider than most people expect.

The concept of nutritional periodisation, aligning your macronutrient targets with the specific demands of your training phase, has moved from elite sports science into practical coaching over the last five years. The research now gives us specific numbers, not just general principles.

Here is what the research supports, why it matters, and what to eat differently across your season.

Why Your Nutrition Needs Should Change With Your Training

Training stress is not constant. In a base-building phase, you might be riding 10 hours per week at mostly low intensity. In a build phase with VO2 max blocks, you might be riding 14 hours with three high-intensity sessions. In a race phase, your volume drops but intensity peaks. The physiological demands on your body are genuinely different across these phases.

The nutritional strategies that best support each phase are correspondingly different. The carbohydrate requirement for a week of Zone 2 base building is substantially lower than the requirement for a week of threshold and VO2 max training. Fuelling both the same way either leaves you underfuelled for hard training or overfuelled during easy phases, where excess carbohydrate serves no particular adaptive purpose.

Beyond macronutrients, the specific adaptations you are targeting in each training phase are also best supported by different nutritional conditions. This is where the train-low strategy becomes relevant.

The Three-Phase Framework

A 2025 project by the UCI Sports Nutrition team, published in the International Journal of Sport Nutrition and Exercise Metabolism, provided one of the clearest frameworks yet for periodised nutrition across cycling training blocks. The recommendations below draw from this research.

Base Phase (typically 10-12 hours per week, mostly Zone 1-2)

Carbohydrates: 4-6g per kg of body weight per day

In base training, training intensity is low enough that carbohydrate availability is rarely the limiting factor for completing sessions. The body runs predominantly on fat at low intensities. Keeping carbohydrate intake at the lower end of the range in this phase has a specific purpose: it promotes the mitochondrial adaptations from training in a glycogen-reduced state.

The strategy here is not to be chronically under-fuelled. It is to be selective. Completing some sessions intentionally fasted or with reduced carbohydrate availability enhances certain signals for mitochondrial biogenesis, essentially training your body to be more efficient with the fuel it has. This is the train-low principle.

Train-low sessions should only be applied to sessions of moderate intensity (Zone 2) where performance is not compromised by low fuel availability. Never apply train-low to threshold, VO2 max, or race-specific sessions. Quality matters more than the metabolic signal.

Protein: 1.6-1.8g per kg of body weight per day

Protein demand is slightly lower in base phase because the training stimulus involves less tissue damage than higher-intensity work. That said, protein should remain a consistent priority. Muscle protein synthesis requires a steady supply, and athletes who chronically undereat protein in base phase often find their body composition drifts unfavourably.

Practical example for a 75kg rider: - Carbohydrates: 300-450g per day - Protein: 120-135g per day - Total calories will vary depending on training volume and body composition goals

Build Phase (typically 12-15 hours per week, mix of Zone 2 and intensity)

Carbohydrates: 6-8g per kg of body weight per day

Once threshold intervals, VO2 max blocks, and race-specific training begin, glycogen demand increases substantially. Hard sessions cannot be properly executed in a glycogen-depleted state. The adaptation signals from high-intensity training require adequate carbohydrate availability.

This is where many cyclists make a crucial error: they continue eating at base-phase levels while their training demands increase. The result is chronically under-fuelled high-intensity sessions, poor recovery, suppressed adaptation, and gradually declining energy availability. Not a recipe for a performance breakthrough.

During build phase, carbohydrate intake goes up, particularly on hard training days. On days with two quality sessions or a very long ride, carbohydrate targets push toward the 8g/kg end. On easier days, 6g/kg is appropriate.

Protein: 1.8-2.0g per kg of body weight per day

Higher-intensity training creates more muscle protein damage, and the repair of that damage requires more protein. The slight increase in protein target during the build phase ensures that recovery keeps pace with training stress.

Practical example for a 75kg rider: - Hard training days: 450-600g carbohydrates, 135-150g protein - Easy days: 350-450g carbohydrates, 135g protein

Race Phase (reduced volume, high intensity, race week)

Carbohydrates: Rising to 8-10g per kg in the final 48-72 hours before the race (carbohydrate loading)

Carbohydrate loading in the final two to three days before a target race saturates muscle glycogen stores, giving you more fuel to draw on during the event. Research supports a specific protocol: maintain normal training (or reduce slightly) while increasing carbohydrate intake progressively from 48-72 hours out.

Race week outside of the loading window looks similar to build phase: moderate-to-high carbohydrate intake on training days, slightly reduced on rest days.

Protein: 1.8-2.0g per kg continues

Race day morning: 2-4g per kg of carbohydrates in the final 3-4 hours before the start line. A large, familiar meal is appropriate if you have time. Within 60 minutes of the start, keep to easily digestible carbohydrates (white rice, banana, a gel or two) to avoid GI issues.

The Train-Low Strategy in Detail

Train-low refers to completing sessions with intentionally reduced carbohydrate availability. The most practical implementations:

Fasted training: Complete a low-intensity morning ride before breakfast. Two to three hours is the typical duration limit for quality fasted sessions.

Sleep-low: Deplete glycogen with an evening session, then sleep without carbohydrate replacement. Complete the following morning's session before eating. This is more aggressive than simple fasted training and should be reserved for athletes with a solid nutrition foundation.

Training with restricted carbohydrates: Ride a moderate-intensity session without carbohydrate intake during the ride, relying on body fat stores and liver glycogen.

All train-low approaches should be used sparingly, typically one to two sessions per week in base phase at most, and only when the sessions are low enough in intensity that quality is not compromised.

What This Means Practically

Nutrition periodisation is not about extreme dietary restriction. It is about alignment. Eat more on harder training days. Eat carbohydrate around the sessions that need it. Use base phase to build your body's fat-burning capacity. Shift to higher carbohydrate availability as intensity increases.

A useful rule: fuel the session in front of you, not the one you just completed. Pre-ride nutrition is more performance-relevant than post-ride nutrition for high-intensity sessions. Both matter, but if you have to prioritise, eat before the session that requires maximum output.

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