Whether you're training for your first or fastest 26.2 miles, you need to develop the right nutrition plan.
There isn't a one-size-fits-all plan for fueling. You need to test various meals and see what works for you. Everyone handles food differently.
Shalane Flanagan, American long-distance runner, KIND bar athlete and Olympic bronze medalist, has improved her nutrition plan over the years.
"Once I started running marathons, I worked with a close friend of my to find the right nutrients that help me perform well, Flanagan says. "Nutrition is essential and I'm working on improving that."
So what does Flanagan's nutrition plan like? It includes fruit, a good balance of protein, fat and carbs and avoids processed foods. Flanagan always rehydrates as soon as she finishes a workout and keeps snacks on her at all times.
More: Top Marathon Recovery Foods
"My go-to is a KIND bar," Flanagan says. "I have it with me all the time—snacks are in my gym bag or purse so I never go hungry."
A sample of Flanagan's meal plan consists of the following:
Breakfast: Oatmeal, coconut water and coffee
Mid-morning snack: Apple and a KIND bar
Lunch: Quinoa bowl or sandwich
Mid-afternoon snack: If Flanagan is hungry, she'll reach for a KIND bar that fulfills her salty-sweet craving.
Dinner: Something that's well balanced in protein, carbs and fat.
What she eats and drinks during her run matters as much as her breakfast, lunch and dinner.
More: Clean Eating Recipes for Athletes
"The only time I fuel mid-run is if I'm simulating a marathon," Flanagan says.
Sometimes, she tries an electrolyte like Gatorade or gels.
"Hydration is huge," Flanagan says. "Drinking while running is hard, it's a skill to learn. It's hard, your GI system is not used to taking in water while running."
Flanagan has gotten over the discomfort by training her body to take in the water.
Flanagan tries not to stop running to take a water break. Instead, Flanagan's coach or husband will hand her some water during her marathon-training runs.
More: How to Reduce GI Distress on Race Day
While pre-run and mid-run fuel keeps you going, it's important to give your body post-run nutrients. When training for a race, Flanagan usually has a piece of fruit and a KIND for so your body recovers optimally. But when it comes for post-race food, her food intake drastically changes.
"I'm usually craving something greasy. After Berlin, I sat down with a German beer and ate a huge plate of fries," Flanagan says. "Once my stomach settles down—a few hours later—I usually have a good burger."
More: Best Post-Race Foods for Athletes
Flanagan loves eating and understands the importance of food and the energy it provides. She is partnering up with one of her good friends to develop a cookbook with some of her favorite recipes.
"We've been testing a lot of our recipes with runners," Flanagan says. "They are really creative, fun ideas."
Flanagan's book hopefully will come out later this year. In the meantime, "keep trying different foods that help you perform your best," Flanagan says.
More: Your Marathon Taper Week Nutrition Plan
Stay healthy with our nutrition guide.