Fueling 26.2

It is incredible to me that women were not allowed to run in the Boston Marathon until the early 1970's, and the first Women's Olympic Marathon wasn't until 1984. I was 4 years old. It is 2019, and I'm blessed to be a woman who has successfully run 2 full marathons before the age of 40. Second only to childbirth, nothing has challenged me more physically or mentally than running 26.2 miles!

This blog post is how I used a little bit of science, and whole lot of experience to FUEL those miles!


The most important nutrient in an athlete's diet is water. Water helps control body temperature, maintain blood volume, and reduces the risk of heat illness. It helps circulate nutrients for the exercising muscle, and eliminates waste products. Losing 2-3% of your body's water will decrease muscle strength and impair performance. Keeping adequately hydrated before and during exercise will improve athletic performance. When your body loses water, it also loses weight. This weight loss is regained when you rehydrate.

Symptoms of Dehydration:



Muscle cramping

Loss of strength


Dark, concentrated urine

Rapid weight loss

Small amounts of urine

Possible heart racing

It is important to note that some of these symptoms are also signs that you are overhydrated, which will deplete sodium levels.

Symptoms of Hyponatremia (low sodium levels in the blood):

Nausea and vomiting



Loss of energy and fatigue

Restlessness and irritability

Muscle weakness, spasms, or cramps



Prerace hydration:

Consistant with the guidelines for hydration, I always drink 2 cups of fluid every morning when I wake up. Urine is usually concentrated at this time from the overnight fast, and it is important to rehydrate regardless if it is race day. If you are really dehydrated, you may need more. Drinking alcohol before race day is not advised, as this will deplete fluid status and B vitamins, which are used by the cells to create energy. Although caffeine is used as a performance enhancer (and the science supports it), I personally must avoid it before and on race day. It makes my bladder overactive, and I want to run--not pee. Listen to your body, and do what works for YOU.

Race Hydration:

Several references use 16-24 ounces of water per hour of effort. Using that guideline, I would need to drink 10-15 cups of water during the entire race! There is a BIG variance here because your fluid needs will depend on the temperature, your effort, and your sweat rate.


If I used those numbers, I would have spent more time in the bathroom than on the pavement! Instead, I used a hydration vest and sipped on water throughout the entire length of my run. I noticed that most runners used small water bottles, or used the aid stations only, but I wanted to drink when I felt the need, and track what actually worked for ME. I ended up drinking about 4 cups according to what was left in my vest. My urine was clear at the end of the race, and I only experienced mild nausea at the end, which I attributed to my usual pain response. Let's face it. The last few miles hurt.

Fueling with FOOD

I'll admit that marathon #1 I forgot my training as a Dietitian, and fell into marketing and "group think" and used gels and an electrolyte drink to fuel my race. Not to say this is wrong--it works for some--but it negates the fact that long before there were man-made products, there was FOOD. Marathon #1 was fueled with an organic gel and the only Gaterade I could find without food dyes (there was 1). I almost puked my way to the finish line! The gels stuck on my tongue, and I personally needed more water than electrolytes.

For me, it was back to food first.

Marathon #2 I skipped the electrolyte drink, hydrated with water and salt tablets, and used real food to keep my blood sugar stable. According to Stacy T. Sims, PhD in nutrition science and exercise physiology, glycogen stores (carbohydrate) last about 2 hours or 15 miles depending on the intensity of the run. It is essential to eat during a marathon. Simple carbohydrates that are easy to digest and absorb are best. Fiber, fat, and protein take longer to digest and absorb (hence, the reason glucose/sucrose gels were born). The preferred fuel for the exercising muscle is carbohydrate. A combination of simple sugars are absorbed quickly, and keep blood sugars stable to meet the demands of your endurance run. If you are following a Paleo/Low carb/Keto meal plan, then you must give your body enough time to adjust to using amino acids (protein) and fat for energy if you are going to take on 26.2. This lifestyle will not be discussed here.

Using the guideline of 100 calories/pound of body weight/hour, I brought foods that provide easily digested carbohydrate that were low in total fat, fiber, and fructose to support digestive health. Dairy can also be a major trigger for some. My body does very well with dairy--until I run for endurance! When exercising, remember that more circulating blood is going to the cardiovascular and muscular systems than the gut, so gastrointestinal distress is common. Find what works best for YOUR body. Make sure to test your tolerance during your training, and remember that nerves on race day can get the best of your stomach too! No new foods on race day!

Race Day Fuel options (dairy free, low fiber, low fructose, and low fat) AS TOLERATED:

1/2 banana

1/3 cup dried apricots or dates (careful, these can make you poo--check label for corn or sulfates)

1 fruit pouch (I used applesauce)

1 fruit leather (strawberry)

15 salted pretzels or gluten free rice crackers

1-2 nut butter/oat/brown rice syrup balls (portion control!)--honey contains fructose!

1 oz beef or turkey jerky

1-2 peanut butter/jelly squares on white or gluten free bread (no whole grains)!


My body doesn't tolerate 100 calories an hour anymore than it will tolerate 16 oz of fluid per hour. My digestive health is always strained when I eat processed corn, during times of extreme stress, and during the adrenaline rush of races. I was able to tolerate applesauce, a few rice crackers, a salt/potassium tablet, and a small oat/peanut butter ball without digestive distress. I do regret eating a large serving of beans the night before the race though! With plenty of fiber in my gut, plus extra hydration, this was the first run where I had to do more than pee. It is tricky to find that balance during extreme sports!

Post marathon Fuel

While it is unnecessary--and inappropriate--to eat back all 2,000+ calories you just burned, it is essential for recovery that you eat a well balanced meal with at least 20-30 grams of protein within 30 minutes to an hour post marathon. Now is the perfect time to drink a recovery beverage that contains protein, a source of potassium, sodium, and carbohydrate. If you tolerate dairy, a cup of milk provides all 4 of those nutrients! Continue to abstain from alcohol until you are properly re hydrated.

Congratulations! You've worked hard, and you should celebrate your success with a non-food reward like a message! After a recovery period, that is just what I chose to do!

Marian McCormick RDN, CPT, CLT is a Dietitian and Women's Fitness Professional who is passionate about wellness, fitness, faith, and family! When she isn't running, she is enjoying time with her 4 boys! You can find FREE 1/2 and full marathon training plans at www.marianmccormick.com

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