Running Nutrition: 5 Ways to Make This Marathon Season Your Best Yet + Free Nutrition Sample Plan
Marathon season is upon us!
As a sports dietitian who works closely with endurance athletes, I can tell you that your nutrition is just as important as your training plan.
The way you fuel during training has a direct effect on how strong you feel, how well you recover, and how consistent your energy is from week to week. A thoughtful and informed approach to eating can help you get the most out of your runs, reduce the risk of fatigue and injuries, and make the overall experience more enjoyable.
Here’s what you need to know:
Understand Your Energy Needs During Marathon Training
Marathon training naturally increases your energy (calorie) needs. Long runs, speed sessions, and back-to-back training days all require more calories, especially from carbohydrates. Carbs are your main source of fuel during endurance exercise, so finding the right amount for your body and training load is important.
Many runners do well with roughly 6–10 grams of carbohydrate per kilogram of body weight per day, adjusting this range based on how much they’re training. Eating enough carbs helps maintain glycogen stores, supports stable energy during workouts, and assists with recovery afterward.
2. Timing and Building Your Meals
What you eat and when you eat both matter during training.
A balanced meal 2–4 hours before a run: something with carbohydrates, a bit of protein, and some fat, provides steady energy without feeling heavy. After your run, a snack with both carbohydrates and protein within about 30 minutes can support recovery and muscle repair.
Training is also the time to test what works for you. Try different pre-run meals and mid-run fuel sources to see what feels comfortable. This helps you avoid any surprises on race day. Runners generally want to skip new foods or supplements on race morning, as they can sometimes lead to digestive discomfort.
After your run: try to eat within 30 minutes, this helps refill your glycogen stores and supports muscle repair.
Race day is NOT the time for experimenting. Training is your chance to find foods that fuel you well and settle comfortably. Stick with familiar foods your stomach handles easily.
3. Hydrate Well, But Not Too Much
Hydration isn’t just about drinking water, it’s about maintaining fluid balance so your body can regulate temperature, support your heart, and keep your muscles working efficiently.
Even mild dehydration can make running feel harder, and starting your training well-hydrated reduces your perception of effort (and makes you feel more energetic!) Research shows that losing more than 3% of your body weight from sweat can negatively affect performance. We want to avoid that at all costs.
Marathon runners need to be smart about how they hydrate, not just to avoid dehydration, but also to prevent over-hydration, which can be just as dangerous. Drinking too much plain water can dilute the body’s sodium levels, leading to a condition called hyponatremia.
The safest approach is to understand your own hydration needs. Monitoring your body weight before and after long runs, and using electrolyte-containing sports drinks, can help you replace both fluids and the minerals you lose in sweat. Research shows that hyponatremia does happen in marathons, especially among recreational runners who may drink more than their bodies need. This is why having a personalized hydration plan is so important for both performance and safety.
Fuel your runs with confidence!
On-demand mini courses that teach runners how to fuel training, recovery, and performance with practical, evidence-based nutrition guidance 👇🏼
4. Preventing Gastrointestinal (GI) Distress
GI issues, like bloating, cramping, nausea, urgent bathroom needsm are extremely common among distance runners. Some studies show that more than half of ultramarathoners experience gut discomfort during long events.
Several factors can contribute, but food choices play a major role.
Some runners are sensitive to high-FODMAP foods, which can ferment in the gut and trigger symptoms. Examples include beans, garlic, onions, certain fruits, and some dairy products. If this is the case, it is important to work with a Registered Dietitian to help narrow down the root causes and soothe your symptoms.
But not everyone has IBS or is sensitive to FODMAPs.
One strategy to help with non-FODMAP related gut distress is gut training: practicing with the exact sports drinks, gels, and carb sources you plan to use on race day. Just like your legs, your digestive system adapts when you train it consistently.
By learning what works for your body, you can build a fueling plan that keeps your stomach calm and your energy stable.
5. Understand Your Sports Supplements
Supplements can support marathon training, but they should only be used when they serve a clear purpose, not because a label promises big results. Many runners can meet their nutrient needs through food, and the supplements with the strongest evidence for endurance performance are usually the simplest ones: electrolytes, carbohydrate gels or drinks for long runs, caffeine (if tolerated), and the occasional protein powder for convenient recovery. Otherwise, endurance runners can benefit from trying out sodium bicarbonate (evidence-based but can cause significant tummy distress) or nitrates (like beetroot).
Be cautious with products marketed as “performance boosters,” especially those with long ingredient lists or bold claims. Choose third-party tested brands (such as NSF Certified for Sport or Informed Sport) is important for safety and quality. And remember: never try a new supplement on race day. Practice your nutrition strategy: gels, sports drinks, or caffeine during training to make sure your stomach tolerates them well.
If you’re unsure what you actually need, a sports dietitian can help you build a simple, safe supplement plan tailored to your training, goals, and diet.
Prefer to consult with a sports dietitian?
Final Words
Marathon training isn’t just about tracking miles on your smart watch, it’s about giving your body the fuel, hydration, and recovery support it needs to perform well and stay healthy. With a solid nutrition plan that matches your training, pays attention to your body’s signals, and is practiced well before race day, you’ll feel stronger, more prepared, and more confident heading into your event. Small, consistent choices add up. With the right fueling strategy, your best marathon season starts long before you reach the starting line.
Hope this helped!
Maria Tanielian
Registered Dietitian/Nutritionniste
IOC Diploma in Sports Nutrition
ODNQ # 7223, CDBC # 2815, SDA # 949, CDO #16856
Studies Worth Reading With An Open Mind
Burke, L. (2007). Nutrition strategies for the marathon. Sports Medicine, 37(4), 344-347. https://doi.org/10.2165/00007256-200737040-00018
Cheuvront, S., Montain, S., & Sawka, M. (2007). Fluid replacement and performance during the marathon. Sports Medicine, 37(4), 353-357. https://doi.org/10.2165/00007256-200737040-00020
Deldicque, L. and Francaux, M. (2015). Recommendations for healthy nutrition in female endurance runners: an update. Frontiers in Nutrition, 2. https://doi.org/10.3389/fnut.2015.00017
Fatima, F., Waheed, S., Asifullah, M., Hassan, T., Samo, N., & Zamurd, B. (2024). Nutritional strategies for optimizing performance in endurance sports: a case study of marathon runners. International Journal of Biochemistry Research & Review, 33(6), 365-378. https://doi.org/10.9734/ijbcrr/2024/v33i6919
Goulet, E. (2012). Dehydration and endurance performance in competitive athletes. Nutrition Reviews, 70, S132-S136. https://doi.org/10.1111/j.1753-4887.2012.00530.x
Heikura, I., Stellingwerff, T., & Burke, L. (2018). Self-reported periodization of nutrition in elite female and male runners and race walkers. Frontiers in Physiology, 9. https://doi.org/10.3389/fphys.2018.01732
Huang, W., Chang, Y., Chen, Y., Hsu, Y., Huang, C., Kan, N., … & Chen, S. (2017). Whey protein improves marathon-induced injury and exercise performance in elite track runners. International Journal of Medical Sciences, 14(7), 648-654. https://doi.org/10.7150/ijms.19584
Ordóñez, F., Valenzuela, P., Gimenez, J., Tur, C., Ferreria, D., Domínguez, R., … & Sanz, J. (2019). Carbohydrate availability and physical performance: physiological overview and practical recommendations. Nutrients, 11(5), 1084. https://doi.org/10.3390/nu11051084
