Whether you’re a seasoned racer or you’re training for your first marathon, one thing is always true: your body is different from every other runner who crosses that finish line. That’s why nutrition is a complicated part of training—because each body is unique. One standard does not work for everyone. However, there are some common nutritional guidelines that will help you come closer to your goals.

Before the Event

Determine your water intake needs. If your body reaches a dehydration level of only 2%, it can result in impaired performance(1). Determining your individual needs can be estimated with a “sweat test.”
1. Before running, get undressed to weigh yourself (after completing your run, your clothes may be heavier due to sweat and skew the results).
2. Run at race pace for one hour while tracking how many ounces of fluid you consume throughout.
3. After your run, strip down and weigh yourself again.
4. Determine your weight loss and convert this number to ounces (1 pound = 16 ounces).
5. Add this number to the number of fluid ounces consumed during your run.
6. This should be about the amount of water your body needs for one hour of running. A further breakdown can be done by dividing this number by 4 to find your needs for every 15 minutes of your race.

Keep in mind that hydration needs can fluctuate based on temperature, clothing, health, and other variables. This estimate is for the conditions of the day the test is performed. While this takes away a little of the science behind planning your race day hydration, it will give you a ballpark number to start with.

Plan your pre-event meals. Race day is one day you do not want to be surprised with a queasy stomach. It typically takes between 24 to 72 hours to fully digest and eliminate food in a healthy individual. Pre-race nutrition is no longer limited to the morning of your run.

It’s not all about pasta. Carb loading is NOT just eating out at an all-you-can-eat pasta dish restaurant the night before your event. This can leave you feeling lethargic if you are not used to the high carbohydrate intake, and a splurge can make you overly full. Carb loading should actually begin three days prior to the race to help your body store adequate fuel for the event. Carbohydrates should be utilized in every meal over several days, spreading out the intake. Try to eat a variety of vegetables, fruits, and whole wheat grains. Focus on low glycemic index carbs and whole foods for three days preceding the event to help your body prepare.

Practice makes perfect. Try out different meals before your long training runs to determine what works best for you. Aim for a well-rounded meal with whole grains (a slow-release carb source), a high glycemic index food for quick energy, and a protein.

Do your Research! Scope out the race. Beforehand, you will want to know:
1. Race route and topography
This will allow you to train smart for the terrain you’ll be navigating, as well as plan your nutrient intake to push through hills and long, flat segments.
2. Replenishing stations
This includes where they are, as well as what is being offered. You don’t want to put anything new into your body that you have not tested before. If they are giving out caffeinated soda, you’ll want to know ahead of time to determine if you should take it or pass it by.
3. Bathroom stations
4. Medical stations

During the Event

If you’re event will last longer than 60-90 minutes, you will need to plan on taking in carbohydrates during your activity to help prevent glycogen depletion and “bonking.” A general rule of thumb is to consume 30-60 grams of carbohydrates each hour throughout your event. However, with every suggestion, there is always an exception, so if this is too much or not enough for your frame, don’t let those numbers disable your judgement.

Hydrate during the event. While you need to be mindful of drinking enough water during your event, it is possible to get too much of a good thing. Hyponatremia is something to be aware of, especially as an endurance athlete. Hyponatremia is caused by low blood sodium levels that can cause headaches, muscle cramps, and even (in extreme cases) seizure or death(2). An imbalance of sodium in the blood stream may be caused by sweating too much without replenishing both fluids and electrolytes. If you are not using an electrolyte supplement, take advantage of the sport drinks handed out at events to maintain a proper balance. Don’t shy away from the calories these drinks contain—your body will use the sugar for a quick energy source.

After the Event

Keep drinking after you cross the finish line. Hydration should happen before, during, and after your run. If you completed the sweat test during your training, you should have a rough estimate of your average fluid loss and therefore your hydration needs. If not, this can be completed on the day of the event by weighing yourself immediately before and after your race. Drink 20-24 fluid ounces of water or sports beverage for every one pound lost(3).

Replenish, rebuild, and repair. Immediately following an event, restore your depleted glycogen stores, fluid loss, and electrolyte balance. A 3:1 or 4:1 ratio of carbohydrates to protein is ideal within 30-45 minutes following an endurance event in order to recover. This will supply glucose and amino acids to repair muscle breakdown. Roughly two hours after the event, another small, well-balanced meal is recommended, including a good carbohydrate source, a protein, and healthy fats.

8 Quick Tips

1. Eat real food. Preceding the event, try to cut back on fast foods, frozen dinners, or canned food.
2. Choose quality carbs: think whole foods, no processing, and clean eating.
3. Write down what you are eating for 1-2 weeks, along with a log of your runs (and how you felt throughout them) to determine what’s working and what’s not.
4. Listen to YOUR body.
5. Stay hydrated before, during, and after.
6. Avoid high-fiber foods that can stimulate the GI tract the morning of your event.
7. Avoid fatty foods, high acidic food, and anything you aren’t used to that can cause GI distress.
8. Don’t pair shot blocks, gels, or GU with sports drinks. They are meant to be paired with water. Combining these with another sugar- and electrolyte-laden source is a recipe for GI havok.


iFit Trainer
Emily Wiley

1. http://www.humankinetics.com/excerpts/excerpts/dehydration-and-its-effects-on-performance
2. http://cjasn.asnjournals.org/content/2/1/151.full

3. chrome-extension://oemmndcbldboiebfnladdacbdfmadadm/https://www.acsm.org/docs/brochures/selecting-and-effectively-using-hydration-for-fitness.pdf