Marathon Training - Hydration and Nutrition

Don’t Forget to Drink and Eat: Hydration and Nutrition for Marathon Training

Sam Vargas PT, DPT, SCS

I’m going to start off by saying, if you have any questions about hydration and nutrition and need thorough advice I highly encourage talking to a sports registered dietitian. Today, I’m going to share generalities for marathon training, and by no means is this all-encompassing. I hope you enjoy the read and find it informative! Do keep in mind we don’t give prescriptive advice over the interwebs, and this is support in a general direction.

I was reading the American College of Sports Medicine (ACSM) recommendations and they provide hydration (and nutrition) recommendations for endurance athletes. These recommendations are designed to help you maintain optimal performance and minimize the risk of dehydration, overhydration—meaning hyponatremia, and related issues. Keep in mind that individual hydration needs can vary based on factors like body size, sweat rate, and environmental conditions.


  • Start each training session well-hydrated. Drink water or a sports drink in the hours leading up to your run.
  • Aim for pale yellow urine as an indicator of adequate hydration.

During Training Runs: start early and drink often

  • Regularly consume fluids during your long training runs, particularly on hot or humid days.
  • The recommended fluid intake during training runs is about 5-10 ounces (150-300 mL) of fluid (water or sports drink) every 15-20 minutes. If that is hard to calculate, generally try to avoid losing more than 2% of your body weight in sweat loss. For example, if I weighed myself before my long run (let’s say 150 lbs before my run, then after I’d want to check again and try to lose no more than 3 lbs. If I lost more weight due to sweat, first I’d begin rehydrating to get back to 150 lbs. Next, all I’d do is take more water with me on the next long run and check again to see if I’m better hydrated.)
  • Consider using a sports drink that contains electrolytes to help replace sodium, potassium, and other electrolytes lost through sweating, especially during longer runs.
  • Listen to your body’s signals for thirst and drink accordingly. Avoid overhydration, which can be just as detrimental as dehydration. This is a big cause for hyponatremia which totally upsets your body’s blood electrolyte balance. No bueno!

Post-Training: drink to get hydration replacements!

  • After training runs, continue to drink fluids to replace any fluid lost. A sports drink or a snack with electrolytes can aid in rehydration and recovery.

With regard to nutrition, I’m going to go even more basic here and say…EAT YOUR CARBS!!!

Proper nutrition is essential for fueling your workouts, promoting recovery, and supporting overall health during the demanding training period leading up to a marathon. You want to consume predominantly carbohydrates (they are fast, usable fuel), with some proteins, lower fats and lower fiber. It is about keeping the rate of absorption high, and not upsetting your stomach.

Pre-Training Meals:

2-3 Hours Before Training:

  • Have a balanced meal rich in carbohydrates, moderate in protein, and low in fat. This meal should provide sustained energy and minimize gastrointestinal discomfort during exercise.
  • Some fun options: Whole grain cereal with milk, oatmeal with berries and nuts, a bagel with jelly and a touch of nut butter.

30 Minutes to 1 Hour Before Training (Optional):

  • If you’re short on time, a small, easily digestible snack can provide a quick energy boost.
  • Some fun options: A banana, an energy bar, or a sports drink.

During Training:

  • For runs lasting longer than 90 minutes, consider consuming carbohydrates in the form of gels, chews, or sports drinks to maintain energy levels. Aim for 30-90 grams of carbohydrates per hour.
  • Experiment with different forms of fuel (chews, goos, gels, etc) during training to see what works best for you, and be sure to practice your race-day nutrition strategy in your long training runs.

Post-Training Meals:

Within 30 Minutes of Training:

  • Consume a recovery snack or meal that combines carbohydrates and protein to replenish glycogen stores and promote muscle recovery.
  • Some fun choices: A smoothie with banana, protein powder, and almond milk, or a turkey and avocado sandwich on whole grain bread.

2-3 Hours After Training:

  • Have a balanced meal that includes lean protein, complex carbohydrates, and vegetables to continue refueling and aid in muscle repair.
  • Some fun choices: Grilled chicken with quinoa and roasted vegetables, or salmon with sweet potatoes and steamed broccoli.

Additional Tips: because we are really just preparing for race day after all 🙂

  • Practice: It’s essential to practice your race day nutrition plan during your long training runs to ensure your body tolerates the foods and fluids you plan to use.
  • Avoid Trying Anything New: Race day is not the time to experiment with new foods or supplements. Stick to what you know works for you.
  • Stay Relaxed: Nervousness can affect your digestion, so try to stay calm and focused in the hours leading up to the race.
  • Pack Your Nutrition: Organize and pack your race day nutrition and hydration supplies the night before to avoid any last-minute stress.
  • Listen to Your Body: Pay attention to how you feel during the race and adjust your nutrition plan as needed. Everyone’s needs are different, so be flexible.

We at Custom Performance want to support you in the best way possible. You need help, we’ve got you covered. You need a referral, we’ve got you covered! Be safe out there on the streets!

By Sam Vargas PT, DPT, SCS

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