Should You Eat More Carbs on Training Days?

According to the International Society of Sports Nutrition, carbohydrates are the primary fuel source for moderate to high-intensity exercise. For this reason, many athletes ask: should you eat more carbs on training days? The answer depends heavily on the intensity and duration of your activity.

Quick Summary

This article explores the optimal approach to carbohydrate intake on training days versus rest days. It covers the benefits of strategic carb timing for performance, recovery, and muscle glycogen replenishment. It also examines how needs vary for different types of workouts and debunks common myths.

Key Points

• Strategic Fueling is Key: Your carbohydrate intake should be periodized to match your training intensity and volume, increasing on hard days to maximize performance and recovery.

• Glycogen Stores Matter: Carbs are crucial for replenishing muscle glycogen, the primary fuel for intense exercise, preventing muscle fatigue and enhancing endurance.

• Timing Impacts Results: Consuming carbs before and after training can provide immediate energy and speed up recovery. For longer workouts, ingesting carbs during the session is also beneficial.

• Beware of Under-fueling: Insufficient carb intake, especially for active individuals, can lead to persistent fatigue, poor performance, and health problems like RED-S.

• Food Choice Flexibility: Both simple and complex carbs have a place in an active person's diet, used strategically to provide quick or sustained energy as needed.

• Needs are Individual: Optimal carb recommendations depend on body weight, training volume, and individual goals, ranging from 5-7g/kg for moderate activity to 8-12g/kg for extreme training.

The Importance of Carbohydrates for Exercise

Carbohydrates are a macronutrient that our bodies convert into glucose, which is then used as fuel or stored in our muscles and liver as glycogen. Glycogen is the primary energy source for your muscles during moderate to high-intensity exercise, including both endurance activities and weightlifting. Consuming adequate carbohydrates ensures that these glycogen stores are sufficiently topped up to support your training demands. Without enough carbohydrates, your body may resort to breaking down muscle protein for fuel, which can hinder recovery and muscle growth.

Fueling for Different Workouts

Not all training days are created equal, and your carbohydrate needs should reflect the specific demands of your workout. A high-intensity, long-duration session, like a marathon run or an extended weightlifting session, will deplete glycogen stores far more than a low-intensity, shorter activity. This means a strategic approach to carb intake is essential, rather than a one-size-fits-all daily allowance. Elite athletes often practice 'periodized' nutrition, adjusting their carbohydrate intake based on their training volume and intensity. For recreational exercisers, a simpler approach focusing on pre- and post-workout fuel is typically sufficient.

The Role of Strategic Timing

While total daily intake is important, the timing of your carbohydrate consumption can have a significant impact on performance and recovery. Eating a carb-rich meal or snack before a workout ensures your muscles have readily available energy, helping to prevent fatigue and maintain high intensity. After your workout, consuming carbohydrates is crucial for replenishing depleted glycogen stores. Combining carbs with protein in the post-workout period can enhance this replenishment process and aid muscle repair.

The Impact on Performance

Numerous studies confirm the positive link between a high-carbohydrate diet and improved athletic performance, especially in endurance events. A study on endurance performance found that athletes on a high-carb diet lasted significantly longer during a time-to-exhaustion trial compared to those on a low-carb diet. The mechanism is straightforward: more available glycogen means more fuel for your muscles, allowing you to train harder and longer before fatigue sets in. This is why practices like 'carb-loading' are so popular among endurance athletes preparing for a race.

Risks of Under-fueling

Consistently under-eating carbs relative to your training demands can lead to a condition known as Relative Energy Deficiency in Sport (RED-S). This can cause a range of health issues, including mood disturbances, reduced sleep quality, and impaired bone health, in addition to negatively impacting athletic performance. Signs of under-fueling often include persistent fatigue, poor recovery, and a plateau or decline in performance. Avoiding this requires not only sufficient total energy intake but also a proper macronutrient distribution that prioritizes carbohydrates on heavy training days.

Comparison: High-Carb vs. Low-Carb on Training Days

Feature	High-Carb Approach (on heavy training days)	Low-Carb Approach (on heavy training days)
Energy Source	Primary reliance on glucose and glycogen for immediate fuel.	Reliance on stored fat and potentially muscle protein via ketosis.
Performance Impact	Supports high-intensity and long-duration exercise, delaying fatigue.	Can lead to reduced training intensity and early fatigue, especially for anaerobic efforts.
Muscle Glycogen	Maximizes glycogen stores pre-workout and rapidly replenishes them post-workout.	Glycogen stores are consistently low, limiting the intensity of workouts.
Recovery	Enhanced muscle glycogen resynthesis and overall recovery, especially when combined with protein.	Can compromise recovery as the body may use protein for energy, not repair.
Nutrient Timing	Crucial, with emphasis on pre- and post-workout intake.	Less critical for immediate fuel, but protein timing remains important for muscle repair.
Best For	Endurance sports, HIIT, strength training, and any moderate-to-high intensity activity.	Lower-intensity, steady-state exercise, or for specific metabolic goals under supervision.

Practical Application: How to Adjust Your Intake

The optimal strategy is to align your carbohydrate intake with your training load, a concept known as 'carbohydrate periodization'. On days with high-intensity or long-duration workouts, increase your carb intake, especially around the workout itself. For moderate exercise (around 1 hour per day), a general guideline is 5-7g of carbs per kg of body weight. On rest or low-activity days, a lower carb intake is generally appropriate to match lower energy expenditure. The goal is to provide enough fuel to perform and recover effectively without excess. For more advanced athletes, this strategy can be highly tailored, with some needing up to 10-12g/kg per day on very demanding days.

Food Choices

• Pre-workout (1-2 hours before): Choose easily digestible, fast-acting carbs to provide quick energy. Examples include a banana, an energy bar, or some crackers.
• During workout (for longer sessions): Consume 30-60g of carbs per hour for workouts over 60-90 minutes. Sports gels, chews, or sports drinks are effective options.
• Post-workout (within 1-2 hours): Focus on a mix of simple and complex carbs with protein to kickstart glycogen replenishment and muscle repair. A smoothie with fruit and protein powder or a meal with chicken and rice are excellent choices.

Conclusion

For those engaging in moderate to high-intensity exercise, increasing carbohydrate intake on training days is a scientifically-backed strategy to enhance performance and optimize recovery. It ensures your body's primary fuel source, muscle glycogen, is readily available and replenished. While needs vary based on individual factors and workout intensity, ignoring your body's need for carbohydrates during strenuous activity can lead to poor performance, fatigue, and potential health issues. By strategically adjusting your carb intake, you can effectively fuel your workouts and achieve better results.

Key Takeaways

• Performance is Enhanced: Eating more carbs on training days provides the fuel needed for higher intensity and longer duration workouts.
• Recovery is Improved: Post-workout carb intake is critical for replenishing muscle glycogen stores and repairing muscle tissue.
• Energy Needs Vary: Your carbohydrate requirements should be adjusted based on the specific intensity and duration of your training session.
• Under-fueling is Detrimental: Consistently low carb intake can lead to persistent fatigue and hinder muscle growth and recovery.
• Timing Matters: Consuming carbs before, during (for long sessions), and after exercise is a strategic way to maximize energy and recovery.

FAQs

Question: Will eating more carbs on training days cause weight gain? Answer: Eating more carbs to match the increased energy expenditure of a hard training session is less likely to cause weight gain, as the fuel is utilized by your muscles. The key is to balance your intake with your activity level.

Question: How many extra carbs should I eat on a heavy training day? Answer: The amount varies, but general guidelines suggest 5-7g per kg of body weight for moderate training and 6-10g per kg for high-intensity training. Listen to your body and adjust based on your energy levels and recovery.

Question: Are simple or complex carbs better for fueling workouts? Answer: Both have a role. Fast-digesting simple carbs are ideal right before and during a workout for quick energy. Slower-digesting complex carbs are better for sustained energy throughout the day.

Question: What happens if I don't get enough carbs on training days? Answer: You may experience fatigue, reduced performance, and poor recovery. In severe cases, your body might start breaking down muscle protein for energy.

Question: Should I eat carbs if I'm trying to lose weight and train? Answer: Yes, but strategically. Your body still needs fuel for effective training. Prioritize carb intake around your workouts and choose nutrient-dense sources to support both performance and fat loss goals.

Question: Is 'carb-loading' only for endurance athletes? Answer: While most commonly associated with endurance sports like marathons, strength training also depletes glycogen. Strategic carb-ups can benefit those in high-volume or high-intensity strength training phases as well.

Question: Can I get enough carbs from a balanced diet, or do I need supplements? Answer: For most recreational athletes, a balanced diet can provide sufficient carbohydrates. For elite or very high-volume athletes, supplements like gels or sports drinks can be a convenient way to meet high energy needs during exercise.

Frequently Asked Questions

Will eating more carbs on training days cause weight gain?

Eating more carbs to match the increased energy expenditure of a hard training session is less likely to cause weight gain, as the fuel is utilized by your muscles. The key is to balance your intake with your activity level.

How many extra carbs should I eat on a heavy training day?

The amount varies, but general guidelines suggest 5-7g per kg of body weight for moderate training and 6-10g per kg for high-intensity training. Listen to your body and adjust based on your energy levels and recovery.

Are simple or complex carbs better for fueling workouts?

Both have a role. Fast-digesting simple carbs are ideal right before and during a workout for quick energy. Slower-digesting complex carbs are better for sustained energy throughout the day.

What happens if I don't get enough carbs on training days?

You may experience fatigue, reduced performance, and poor recovery. In severe cases, your body might start breaking down muscle protein for energy.

Should I eat carbs if I'm trying to lose weight and train?

Yes, but strategically. Your body still needs fuel for effective training. Prioritize carb intake around your workouts and choose nutrient-dense sources to support both performance and fat loss goals.

Is 'carb-loading' only for endurance athletes?

While most commonly associated with endurance sports like marathons, strength training also depletes glycogen. Strategic carb-ups can benefit those in high-volume or high-intensity strength training phases as well.

Can I get enough carbs from a balanced diet, or do I need supplements?

For most recreational athletes, a balanced diet can provide sufficient carbohydrates. For elite or very high-volume athletes, supplements like gels or sports drinks can be a convenient way to meet high energy needs during exercise.