How many carbs should an athlete have a day?

According to the International Society of Sports Nutrition (ISSN), carbohydrate intake recommendations for athletes range from 3 to 12 grams per kilogram of body weight daily, depending on training demands. This detailed guide will explore how many carbs should an athlete have a day to maximize their performance, endurance, and recovery.

Quick Summary

An athlete's daily carbohydrate needs are highly dependent on their training volume, intensity, and body weight. Optimizing fuel intake before, during, and after exercise is crucial for maintaining performance, replenishing glycogen stores, and aiding in muscle repair.

Key Points

• Daily Intake Varies: An athlete's carb needs range from 3-12 g/kg/day, directly correlating with training intensity and duration.

• Timing is Key: Optimize performance by strategically consuming carbohydrates before, during, and after exercise to manage blood sugar and glycogen stores effectively.

• Know Your Carb Types: Use complex carbs (e.g., whole grains) for sustained energy and simple carbs (e.g., gels) for rapid fuel during and immediately after workouts.

• Carb Loading for Endurance: A specific high-carb strategy is beneficial for events over 90 minutes, while it may not be necessary for shorter or less intense exercise.

• High-Carb is Generally Superior: While low-carb diets can be adapted, high-carb fueling is generally recommended for optimizing high-intensity performance and recovery for most athletes.

• Refuel Quickly Post-Workout: Consuming 1.0-1.2 g/kg/h of high-GI carbs immediately after intense exercise is crucial for rapid glycogen replenishment.

Understanding the Role of Carbohydrates for Athletes

Carbohydrates are the body's primary and most efficient energy source for fueling moderate to high-intensity exercise. When consumed, they are broken down into glucose, which is either used immediately for energy or stored in the muscles and liver as glycogen. Depleted glycogen stores are a major cause of fatigue and decreased performance, making strategic carbohydrate intake essential for any athlete. The quantity and timing of these carbs must be periodized and tailored to the specific demands of an athlete's training program and competition schedule.

Calculating Your Daily Carbohydrate Needs

An athlete's carbohydrate requirements are not a fixed number but vary greatly depending on the volume and intensity of their training. The most effective method for estimating needs is based on grams per kilogram of body weight (g/kg). Here are the general recommendations, according to various sports nutrition guidelines:

Daily Carbohydrate Targets by Training Load

• Very Light Exercise (Skill-based training): 3–5 g/kg/day.
• Moderate Intensity (Approx. 1 hour/day): 5–7 g/kg/day.
• High Intensity (1–3 hours/day): 6–10 g/kg/day.
• Elite/Ultra-Endurance (>4 hours/day): 8–12 g/kg/day.

For example, a 70kg athlete performing a moderate-intensity workout for one hour would require approximately 350–490 grams of carbohydrates per day to maintain energy levels and support recovery.

The Crucial Role of Carbohydrate Timing

When an athlete consumes carbohydrates is almost as important as the quantity. Strategic timing helps maintain blood glucose levels, provides fuel for working muscles, and maximizes glycogen resynthesis during recovery.

Timing Your Carb Intake

• Pre-Workout (1–4 hours before): Consume 1–4 g/kg of easily digestible carbohydrates. Lower amounts are recommended closer to the start of exercise to avoid gastrointestinal discomfort. Prioritize complex carbohydrates for a steady release of energy in the hours leading up to an event.
• During Exercise (>60 minutes): For prolonged, high-intensity exercise, consuming 30–90+ grams of simple carbohydrates per hour is recommended. Intake can be increased for longer durations (e.g., up to 120 g/h for ultra-endurance) using mixed carbohydrate sources (glucose and fructose) for better absorption.
• Post-Workout (within 4 hours): Replenishing glycogen stores is critical for recovery. A dose of 1.0–1.2 g/kg/h of high-glycemic index carbohydrates is recommended for the first 4 hours, especially if there is a quick turnaround between sessions.

Choosing the Right Types of Carbohydrates

Not all carbs are created equal. The type of carbohydrate you choose should align with your timing and performance goals.

Fueling with the Right Carbs

• Complex Carbohydrates: These are long-chain sugars found in whole grains, oats, brown rice, sweet potatoes, legumes, and fruits. They provide a slower, sustained release of energy and are ideal for fueling daily activities and pre-exercise meals.
• Simple Carbohydrates: Composed of one or two sugar molecules, simple carbs like those found in sports drinks, gels, and fruit provide a rapid energy boost. They are best utilized during and immediately after exercise for quick absorption and glycogen replenishment.

Carbohydrate Strategy: High-Carb vs. Low-Carb for Athletes

While high-carb diets are the traditional gold standard for performance, low-carb and ketogenic diets have gained attention. It's important to understand the trade-offs.

Feature	High-Carbohydrate Diet	Low-Carb/Keto Diet
Primary Fuel Source	Glycogen (stored carbohydrate) and blood glucose.	Ketone bodies from fat metabolism.
High-Intensity Performance	Superior. Carbohydrates are the primary fuel for anaerobic glycolysis needed for short, explosive efforts.	Impaired. Limited fuel for anaerobic glycolysis, reducing power output and leading to early fatigue.
Endurance Performance	Optimal. Maximizes muscle glycogen stores and delays fatigue, especially in events over 90 minutes.	Can achieve similar steady-state performance in some cases, but with reduced economy (more oxygen required per calorie).
Training Adaptation	Supports high-volume training and maximizes training quality.	Disruptive initially; may lead to reduced training intensity during the adaptation phase.
Recovery	Crucial for replenishing glycogen stores quickly, aiding in muscle repair.	Impaired glycogen replenishment, which can delay recovery, especially between back-to-back training sessions.
Weight Management	Effective when calibrated for caloric needs; helps prevent muscle catabolism.	Initial rapid weight loss often due to water loss. Long-term weight loss depends on overall calorie balance.

Special Strategy: Carbohydrate Loading

For endurance events lasting over 90 minutes (e.g., marathons, triathlons), carb loading can significantly boost performance and delay fatigue. The modern approach involves increasing carbohydrate intake to 7–12 g/kg/day for 1–3 days before the event while tapering training volume. Focusing on easily digestible, low-fiber carbs (like white rice, pasta, and juices) can help prevent gastrointestinal issues on race day.

Practical Tips for Meeting Your Carb Goals

Here are some actionable tips for incorporating carbohydrates effectively into your diet:

• Prioritize Complex Carbs in Meals: Build your main meals around quality complex carbs like whole grains, starchy vegetables, and legumes to provide a sustained energy source.
• Embrace High-Density Carbs: If you have high daily needs, choose calorie-dense carbohydrate sources like rice, pasta, and bagels to increase intake without excessive bulk.
• Drink Your Carbs: Liquid carbs, such as sports drinks or smoothies, are a convenient way to meet high energy demands, especially post-workout or during long training sessions.
• Reduce Fiber and Fat Strategically: While fiber and healthy fats are essential, limiting their intake immediately before and after intense exercise can prevent digestive issues and speed up nutrient absorption.
• Plan Your Meals and Snacks: Distribute your carb intake throughout the day with regular meals and snacks to maintain energy levels and ensure optimal fueling.
• Listen to Your Body: Pay attention to how your body responds to different carbohydrate strategies. Experiment with types and timings during training to find what works best for you on competition day.

Conclusion: Personalize Your Fueling Strategy

There is no single answer to how many carbs an athlete should have a day. The optimal amount is a moving target, dictated by your specific training regimen, body weight, and performance goals. By understanding the role of carbohydrates, implementing strategic timing, and choosing the right types of carbs, athletes can create a personalized fueling plan that optimizes performance and accelerates recovery. Working with a sports nutritionist can help fine-tune these strategies to meet your individual needs.

For more in-depth information, you can read the ISSN Position Stand on Nutrient Timing.

Disclaimer

This article provides general information and recommendations. Individual nutritional needs can vary, and it is always recommended to consult with a qualified sports dietitian or healthcare professional before making significant changes to your diet.

Frequently Asked Questions

What is the primary benefit of carbohydrates for athletes?

Carbohydrates are the body's main energy source, especially during moderate to high-intensity activities. They fuel the muscles and brain, improving endurance and performance while delaying fatigue caused by glycogen depletion.

Should strength athletes eat as many carbs as endurance athletes?

Not necessarily. Endurance athletes typically have higher carbohydrate needs (7-10 g/kg/day) than strength athletes, who may need slightly less (4-7 g/kg/day), though optimal intake for strength training depends on session volume and intensity.

How quickly should an athlete consume carbs after a workout?

For rapid recovery, especially with a short turnaround, an athlete should consume 1.0–1.2 g/kg of high-glycemic carbohydrates within the first 30–60 minutes after exercise. This helps maximize glycogen resynthesis.

Are low-carb or keto diets good for athletic performance?

For most athletes, especially those performing high-intensity exercise, low-carb diets are not recommended. They can impair high-intensity performance, reduce recovery, and negatively impact overall training quality.

What are some good sources of complex carbohydrates for athletes?

Excellent sources of complex carbohydrates include whole grains like oats and brown rice, starchy vegetables such as sweet potatoes, and legumes like lentils and chickpeas.

What is carb loading, and when is it necessary?

Carb loading is an endurance strategy involving increased carbohydrate intake (7-12 g/kg/day) over 1-3 days before an event lasting more than 90 minutes. It boosts muscle and liver glycogen stores to improve performance and endurance.

What happens if an athlete doesn't consume enough carbohydrates?

Insufficient carbohydrate intake can lead to muscle glycogen depletion, resulting in fatigue, decreased performance, impaired recovery, and potentially an increased risk of injury.