High Contrast Mode:

Health & Wellness
2/09/2023 by Alissa Palladino

Ask a Dietitian: Fuel Up for Your Marathon or Half Marathon

Nutrition plays a powerful role in successfully training for and completing a race of any distance, and this is especially true for longer events such as the marathon and half-marathon. While there is a lot of individual variation and every runner must ultimately experiment to figure out what's going to work best for them, here are some science-based guidelines and practical strategies to help you dial in on a fueling plan to crush your race-day goals and feel great doing it.


First, the basics. All the energy, or calories, in our diets comes from one of three macronutrients: carbohydrates, protein and fat. While all are essential and must be consumed in balanced amounts for optimal body functioning and overall health, carbs take the spotlight when it comes to fueling for endurance running. The primary role of carbs in our bodies is to provide a quick, readily available source of energy for our muscles and other vital organs. Protein and fat take longer to digest and support other biological processes, like muscle repair and growth, exercise recovery, immunity, satiety, hunger management, inflammation, hormone regulation and more.

Carbs as Performance Fuel

Carbs become increasingly important for long training runs and races. Consuming carbs pre- and mid-run provides energy, improves endurance, delays fatigue, prevents muscle protein break and maintains blood glucose levels. Carbs are also the only fuel available for high intensity (anaerobic) exercise, which experienced runners may hit when doing speed workouts or running shorter events at "race pace."

Pre-Run Nutrition

Carbohydrates should be the focus of pre-run nutrition. Moderate amounts of protein may also be tolerated depending on how much time you have before your run, but typically low-fiber and low-fat foods are recommended to prevent GI distress. The closer you are to running, the more you want to focus on simple carbs, including various forms of sugar (yes, this is the opposite of general healthy eating guidelines).

If you have 3 to 4 hours before your run, a balanced meal that contains ample carbs but also some protein and fat works fine, such as a bagel with peanut butter or a turkey sandwich. If you have 1 to 2 hours, a carb-rich snack paired with a little bit of protein is ideal, such as a banana with peanut butter or a small bowl of cereal with milk. If you find yourself with less than an hour to go, stick to quick-digesting carbs such as a fig or grain-based granola bar, pretzels, dried fruit such as raisins or apricots, graham crackers, a pouch of instant oatmeal, toast with jelly, apple sauce or pureed fruit. Liquid carbs such as a sports drink or juice are ideal immediately before exercise.

Mid-Run Nutrition

On runs lasting longer than 60 minutes, it is essential to take in fuel on the run so you can keep going after glycogen (stored carbs in the muscle and liver) starts to get depleted. Aim for 30-60 grams of carbs per hour, starting at the 45-minute mark to allow time for absorption. There are a wide variety of products designed for mid-run fueling, and you can also opt for whole food options as long as you hit the recommended amounts. Note again that sugar, the simplest and most readily available source of carbs, is beneficial here and not to be feared in the context of performance nutrition.

In fact, most traditional sports products such as GU gels, Clif shot blocks, sports beans and Honey Stinger waffles are composed of sugar as their main ingredient, typically providing 20-25 grams per serving. They are hypertonic (meaning more concentrated than blood) and therefore are designed to be taken with water.

Some newer and novel options available work slightly differently. For example, UCAN contains resistant starch for a slower release of carbs that may provide more steady energy and prevent blood sugar spikes. Maurten uses a hydrogel aimed to provide more-sustained energy and decrease the need for water. It also utilizes a blend of sugar types to allow for a greater intake of carbs per hour. Huma incorporates chia seeds into its gels, providing small amounts of fiber and protein to delay carb delivery for a more-sustained release of energy.

Some runners prefer to fuel with honey, maple syrup, dried fruit, fruit leathers or even candy. Individual preferences and tolerance vary greatly, so it is important to practice during training, find what works for your body, and then stick to your fueling strategy on race day. No matter which form you choose, remember to get those carbs in early and often during your long runs - your energy levels will thank you!

Keep in mind, mid-run fueling guidelines are based on time, not distance. The longer you are out there, the more fuel you will require to keep going feeling energized and strong, so plan and prepare accordingly. For example, a 5-hour marathoner aiming to refuel every 45 minutes will need to carry and consume approximately 150 to 300 grams carbs throughout their race, which might look like up to 6 gels or equivalents, plus two servings of a carb-containing hydration formula. The fueling plan for a 3-hour marathoner, on the other hand, would consist of 90 to 180 grams carbs total, approximately three to four servings of gel or equivalent and one serving of a carb-containing hydration formula.

Post-Run Nutrition

Refueling as soon as possible after long runs, when muscles are primed for nutrient absorption, enhances the recovery process. Your post-run meal or snack should contain carbs to replenish glycogen stores, protein to support muscle repair, and a small amount of healthy fats if tolerated to decrease inflammation. Bonus if you can get in some colorful fruits and veggies for vitamins, minerals and antioxidants.

If your post-run window corresponds with a regularly scheduled meal time, eat a nutritious meal that contains a balance of food of groups, such as a veggie omelet with toast (breakfast), tuna salad in whole wheat pita (lunch) or stir-fry with rice, veggies and chicken/tofu (dinner.)

If it's going to be several hours until your next meal or your appetite is greatly diminished, try a post-run snack such as Greek yogurt with berries and granola, hard-boiled eggs and grapes, a protein shake with a banana, or a fruit and yogurt smoothie.

Race-Week Fueling (Meals)

You have made it through training and are ready to dial in on your nutrition to optimize race day success. The goal in the week or days leading up to your marathon or half marathon is to fully load your muscles with glycogen (stored energy.) To do so, increase the amount and proportions of carbs at each of your meals. Try to fill half your plate with a carb-rich food such as pasta, rice, potatoes, other grains and fruit. For example,

· Breakfast: 2 cups of oatmeal made with milk, topped with nuts and fruit

· Lunch: 2 cups of spaghetti with meatballs, tomato sauce, and broccoli

· Dinner: Stir fry with 2 cups of rice, chicken or tofu, and mixed veggies

You can also add carb-rich snacks on the side of your meals if needed, such as a turkey sandwich made with two slices of bread plus a side of pretzels or a black bean burger on a bun with lettuce and tomato, along with a side of sweet potato fries. Drink to thirst, primarily water, aiming for pale yellow urine.

The Night Before (Dinner)

Like your race-week meals, make carbs the priority in your pre-race dinner. But even more importantly, stick to familiar foods that you have tolerated well during training. The night before your marathon or half marathon is NOT the time to try anything new food wise - save that for your post-race celebration. Hydrate with water and add electrolytes, especially if conditions are expected to be hot and humid on race day. Or just salt your foods a bit more heavily than usual.

Race Morning (Breakfast)

Once again, the key here is to stick with familiar foods that worked for you during training. To get into specific numbers, the recommendation is 1 to 4 grams of carbs per kg of body weight in the 1 to 4 hours before your marathon or half marathon, For a 150-pound (68 kg) runner, that's 70 to 270 grams of carbs - a fairly large wide range and why you need to practice during training to figure out what timing and amount works best your body. Additionally, hydrate with at least 16 ounces of fluid in the 2 hours before race start. Here are a few examples of what a pre-race breakfast would look like with common foods at the various recommended intake levels:

Clif Bar and banana = 70 grams of carbs (1 gram per kg for a 150-pound runner)

Bowl of oatmeal (1 cup dry) made with 1 cup dairy or soy milk topped with ¼ cup raisins and 1 Tbsp. honey plus 8-ounce glass of orange juice = 135 grams of carbs (2 grams per kg for a 150-pound runner)

Three toaster waffles with 2 Tbsp. maple syrup, sliced banana and ¼ cup raisins plus a Clif bar and 8-ounce glass of orange juice = 200 grams of carbs (3 grams per kg for an 150-pound runner)

Bagel with peanut butter, 4 Tbsp. jelly and sliced banana plus 1 cup yogurt topped with ½ cup granola and 12-ounce glass of orange juice = 270 grams of carbs (4 grams per kg for an 150-pound runner)

Less Than 60 Minutes to Race

If you ate early, consider adding a small carb-rich snack immediately before the race to top off energy stores. A specialty sports product or liquid option such as Powerade may be better tolerated at this stage.

The Takeaway:

Nutrition is a powerful tool to help optimize your training and perform to capacity on race day. Everyone is unique, and it may take some trial and error to figure out what's going to work best for you and your body. Make sure to practice your fueling strategy during training and don't try anything new on race day!

Alissa is an Atlanta-based registered dietitian nutritionist and certified personal trainer dedicated to helping people optimize health and athletic performance by harnessing the power of nutrition. Alissa currently offers virtual and in-person nutrition consultations, meal planning services and metabolic testing. Learn more at https://alissapalladinonutrition.squarespace.com or contact her at apalladinordn@gmail.com