Your Caloric Needs Soar During Training
Starting a marathon training plan drastically increases your daily energy expenditure, meaning your body needs more fuel to keep up with the demand of consistent, long-distance running. The consequence of not increasing your caloric intake is a negative energy balance, which can lead to muscle loss, increased risk of illness, chronic fatigue, and poor sleep quality. To perform your best, you must deliberately increase your daily calorie intake with nutrient-dense foods, not junk food.
The specific amount of extra calories needed depends on several factors, including your weight, the intensity and duration of your training, and your overall activity level. For example, athletes training for two to three hours per day, five to six days a week, may need anywhere from 2,000 to 7,000 calories per day to support their activity level, according to the International Society of Sports Nutrition (ISSN). A practical guideline suggests a general increase of around 1,000 calories per day during heavy training, but this should be adjusted based on how your body feels and responds. Learning to listen to your body's hunger and energy cues is an essential skill throughout your training block.
The Science of Macronutrients for Marathoners
As your training load increases, your body's demand for all macronutrients—carbohydrates, protein, and fat—also rises. However, the distribution of these macros requires strategic attention to optimize your performance and recovery.
Carbohydrates: The Primary Fuel Source
Carbohydrates are your body's most efficient and preferred energy source, especially during moderate to high-intensity exercise like marathon running. They are converted to glucose and stored as glycogen in your liver and muscles. During long runs, these glycogen stores are rapidly depleted, which can lead to the dreaded "bonk" or "hitting the wall" if not replenished. To ensure adequate glycogen stores, athletes on intense training schedules should consume 5–8 grams of carbohydrates per kilogram of body weight per day.
Examples of carbohydrate-rich foods include:
- Complex carbs (slow-releasing): Oats, brown rice, quinoa, whole-wheat bread, and sweet potatoes.
- Simple carbs (fast-releasing): Energy gels, sports drinks, bananas, and white rice.
Protein: Crucial for Repair and Recovery
Protein is essential for rebuilding and repairing muscle tissue damaged during intense exercise. The ISSN recommends an intake of 1.4–1.8 grams per kilogram of body weight per day for marathon runners. This protein should be consumed consistently throughout the day and is particularly important in the post-run recovery window (within 30-60 minutes) to maximize muscle repair and growth.
Good sources of protein include lean meats, fish, eggs, dairy products, tofu, and legumes.
Healthy Fats: Long-Term Energy
While fats are not the primary fuel for high-intensity running, they are a vital energy source for lower-intensity efforts and overall health. Fats aid in hormone regulation and vitamin absorption. The ISSN suggests keeping fat intake at around 30% of total calories, though this can be adjusted to meet higher caloric needs. Good sources include avocados, nuts, seeds, nut butters, and olive oil.
Fueling Strategies: Before, During, and After Your Run
Timing your nutrition correctly is as important as what you eat. Here's a quick guide to strategic fueling:
- Before a run: Aim for a full meal 3-4 hours prior, focusing on carbohydrates and moderate protein. If you're running earlier, a smaller, carb-rich snack (e.g., a banana with peanut butter) 1-2 hours before is sufficient. Avoid high-fiber or high-fat foods that can cause gastrointestinal distress.
- During a run: For runs over 90 minutes, start consuming 30-60 grams of simple carbohydrates per hour to prevent glycogen depletion. Options include energy gels, chews, or sports drinks. Practice this during training to train your gut.
- After a run: The 30-60 minute window post-run is ideal for replenishing glycogen and repairing muscles. A mix of carbohydrates (45-60g) and protein (15-20g) works best. Chocolate milk, a turkey sandwich, or a smoothie are excellent choices.
Comparison of Macronutrient Intake on Training vs. Rest Days
Your dietary focus should shift based on your training load. A good nutrition strategy is not a rigid daily plan but a flexible one that adapts to your activity level. The table below outlines how to adjust your macronutrient emphasis.
| Macronutrient | Hard Training Day | Rest/Easy Day |
|---|---|---|
| Carbohydrates | Higher intake (5-7g/kg/bw), prioritizing easy-to-digest carbs pre- and post-workout. | Slightly lower intake (3-5g/kg/bw), focusing on higher-fiber whole grains, fruits, and vegetables. |
| Protein | Extra emphasis on recovery, with 25-30g per meal and an extra 15-20g immediately post-workout. | Consistent intake throughout the day (1.4-1.8g/kg/bw) to support muscle repair and satiety. |
| Fat | Reduce fat intake around intense workouts due to slow digestion, but include healthy fats in meals. | Moderate intake of healthy fats from sources like olive oil, nuts, and seeds to support hormonal health. |
| Hydration | Increased focus on fluid and electrolyte replacement, particularly for long runs. | Maintain consistent fluid intake throughout the day to support overall bodily functions. |
Hydration: The Often-Overlooked Component
Adequate hydration is critical for regulating body temperature, transporting nutrients, and supporting cardiovascular function. During marathon training, you lose a significant amount of fluid and electrolytes through sweat. Dehydration can rapidly lead to fatigue and decreased performance, while over-hydration can lead to hyponatremia. Monitoring your urine color (aiming for a light yellow) and tracking your sweat rate during training runs can help you establish your personal hydration needs. Replenishing electrolytes, especially sodium, is also key, particularly during long or hot runs. Many runners use electrolyte tablets or sports drinks for this purpose.
Common Nutrition Mistakes to Avoid
- Trying new foods on race day: Never experiment with a new food, gel, or drink on the day of your race. You should practice your race-day nutrition strategy during your long training runs to ensure your stomach tolerates it.
- Neglecting recovery nutrition: Skipping the post-run meal or snack within the ideal window (30-60 minutes) can hinder muscle repair and glycogen replenishment, impacting future training sessions.
- Overemphasizing carb-loading: The old-school method of severely restricting and then overloading carbs is no longer recommended. A more moderate increase in carb-rich foods over 1-3 days, combined with tapering training, is more effective.
- Insufficient protein intake: While carbohydrates are the primary fuel, under-consuming protein can impair muscle repair and recovery, increasing injury risk.
- Ignoring hydration and electrolytes: Focusing only on food and neglecting fluids and electrolytes can lead to dehydration or cramps, severely impacting performance.
Conclusion: The Fuel for Your Finish Line
So, do you need to eat more during marathon training? Yes, but it is part of a larger, more nuanced nutritional strategy. Successful marathon training is a delicate balance of increased overall calories and strategically timed and proportioned macronutrients. By focusing on nutrient-dense whole foods, adjusting your intake based on training load, and practicing your race-day fueling plan in advance, you can provide your body with the high-quality fuel it needs to perform, recover, and reach the finish line strong. Consulting a sports dietitian can help fine-tune your nutrition for optimal results and is a worthy consideration for serious runners.
For more detailed guidance on building your race-day strategy, resources from experienced running coaches and dietitians can be invaluable.
