Claire Shorenstein's Nutrition Guide for Long-Distance Runners

Running season is approaching, and so we at GOREWEAR decided to interview Sports Dietitian Claire Shorenstein to learn more about how to fuel for endurance races and feel your best at the finish line and beyond.

Let Us Introduce Claire

Claire Shorenstein, MS RD CSSD is a Board-Certified Sports Dietitian with over 10 years of experience, as well as a longtime endurance athlete. Through her private practice, ​​Eat for Endurance​​, she helps active people feel and perform their best in their athletic and everyday lives. Claire provides various virtual and in-person services and hosts ​​The Eat for Endurance Podcast​​. Follow her on Instagram ​​here​​.

Here's what you'll learn about in this post:

1. Fueling Strategies for Different Race Distances

2. Food Preparations Ahead of Race Day

3. Morning Fueling on Race Day

4. The Best Carbohydrate Sources For Sustaining Energy

5. How To Maintain Energy Levels

6. Post-Race Nutrition Strategy For Recovery

1. How do Fueling Strategies Differ Between Races of Different Lengths?

When deciding on a fueling strategy, you always have to think about the context. Running 26.2 miles on roads is very different from running 50 or 100 miles in the mountains. However, it’s not just the duration of the activity that you need to think about, but also weather, altitude, terrain, pace, and anything else specific to your event. 

Fueling for marathons or ultra-marathons has many things in common, but they require a different fueling approach. For both, you should choose easy-to-digest carbs to provide quick energy, with a target of around 60-90g of carbs per hour. High-carb fueling is all the rage these days, but be cautious about going >90g/hr unless you've established that you can take this in for long periods of time.

In marathons (and half marathons), this mostly consists of gels, chews, and sports drinks. These types of products are easy to carry, and tolerated well at high intensities. Marathoners typically do not need any macronutrients but carbs while racing.

In ultras, athletes frequently use these same sports nutrition products as marathoners but also add in solid foods to provide more carbs plus some protein and fat to prevent hunger. It's key to have a variety of tastes, textures, and solid/liquid fueling options when running these longer distances. 

Both marathoners and ultramarathoners need adequate fluids and electrolytes throughout their races. Fluid and salt losses are very individual and also impacted by the environment (e.g. temperature, altitude), so I recommend that all runners do a simple sweat or fluid loss test at least once or twice during the training cycle to determine their needs. Be sure to include electrolytes (primarily sodium) in your fueling strategy, and pay attention to how much salt you consume relative to fluid amounts. 

Learn more about hydration for endurance athletes here.  

If you’re an ultramarathoner and looking to dial in your protein intake while running, this International Society of Sports Nutrition Position Stand recommends an intake of 5-10g of protein per hour, or 20-30g every 3 hours. You can reach this goal by eating bars or other solid foods, or drinking recovery drinks.

There are no specific intake guidelines for fat while running an ultramarathon, but that doesn't mean these athletes shouldn't consume it. Here are a few things to keep in mind when experimenting with fat-containing foods and products during a run:

• Fat takes longer to digest, so it may be tolerated less, especially while running. Start with very small amounts, and increase as tolerated/desired. 

• Your need for fat may increase as your time exercising increases. Make sure you're not having so much fat that you are unable to meet your carb goals!

• Fat is very calorific, which is a good thing when you're burning tons of energy for many hours. 

• Foods with fats are usually a welcome flavor change from sweet gels and drinks, and may help you continue to get calories in. 

Whether you’re racing a marathon or an ultra, personalizing your fueling strategy and practicing it in training is essential to your success. 

2. What Should You Eat in the Days Leading up to a Race?

All runners who are racing an event >90 minutes should carb load in the 2-5 days prior to their event. Carb loading is a performance nutrition strategy that involves intentionally increasing your intake of carbs before a race to increase your glycogen or energy stores in your muscles and liver. 

Research studies show that carb loading can improve performance by 2-3% during an endurance event. Depending on how long your race is, that could mean shaving minutes (or more) off your time, and feeling better while doing it, too.

You do not need to do a full carb load prior to every long training session, as you're not pushing yourself as hard or going as long as you would be on race day. That said, it's helpful to practice a "mini" carb load (i.e. just for one day) before your longest training sessions so you get a feel for how to do it and which types of foods you tolerate best. 

Before you attempt a carb load, I encourage you to spot-check your regular carb intake for a few days on an app like Cronometer. This is not a calorie counting exercise - it's to get a better understanding of where you're currently at, so you can figure out an appropriate carb loading target. 

Endurance athletes need 5-12g/kg/day of carbs, depending on the volume and intensity of exercise. If you realize you're not consuming enough carbs (i.e. <5g/kg/day) and your event is relatively soon, then you will not feel good doing a "by-the-book" carb load. You will need to take a slightly different approach.

Research suggests that you should aim for an intake of 10-12g of carbs per kg bodyweight per 24hr for 36-48 hours before an endurance event. For instance, a common recommendation might be 10g/kg/day for 2 days. 

Some recreational athletes find these higher carb amounts challenging to reach. In this case, a more practical target might be 8g/kg/day for 3 days. If you're fueling adequately with carbs during training (i.e. taking in at least 5-7g/kg/day), this should be a bump up but not that much above your baseline intake.

If you're not able to tolerate 8g/kg/day (e.g. because your baseline daily intake is on the lower side), you can take a modified approach by setting a slightly lower carb target (e.g. 6g/kg) over 4-5 days. The idea is that you're still increasing your carb intake above your baseline amount, but within a range that you can actually tolerate. 

Whatever number you end up with as your carb loading daily goal, take that number and divide it up into the number of meals and snacks you typically consume each day. For example, if you eat 3 meals and 3 snacks, you can figure out roughly how many grams of carbs to eat at each meal and snack. 

This article has everything you’ve ever wanted to know about how to do a carb load, including which foods are best, what a sample day of carb loading might look like, and troubleshooting common problems.

3. What Should You Eat the Morning of a Race?

What you need and choose to eat will vary depending on your body size, taste preferences and tolerances, as well as what type of event you’re doing. Many races start early in the morning, but others (like the Boston and NYC marathons) start late morning, while others start in the evening or middle of the night! 

It’s crucial to practice your planned pre-race meal before long training runs to make sure that they work well for you. Think about logistics, such as where you’ll be (home, hotel, driving, race start, etc), and what you’ll have access to. If it’s a late start race but you need to leave home early, you may need to eat multiple meals and/or snacks.

If you're looking for a general goal to target, try to eat at least 60-90g of carbs 1-3 hours before you start your run. I suggest that you individualize this recommendation by calculating 1-4g carbs per kg bodyweight, and consume this amount of carbs 1-4 hours before you begin. 

In other words, if you have 4 hours before your race, you would calculate 4g/kg of carbs and consume that amount across those 4 hours so you’re not consuming that amount in one sitting (that would be tough!). 

Along with the carbs, aim to have a small amount of protein (e.g. 10g). If it’s many hours before your race, you may also want to include a little fat to keep you full. A popular, easy option is to add 2 Tbsp of peanut butter to your bagel or oatmeal.

You also need adequate fluids so that you can start your run well-hydrated. First, make sure you're meeting baseline daily hydration needs by taking your weight in pounds and dividing by 2, to give ounces per day. Then, account for what you lose in sweat by measuring your sweat rate.

A general fluid goal before a long run is to drink 16-24oz of fluid 1-3 hours before you start, and remember that this includes coffee, tea, water, juice, sports drink etc. You may need more fluid if you sweat heavily. 

I often recommend to include electrolytes in the form of a sports drink before a race, especially if it's warm out and/or you're a heavy and/or salty sweater. This will improve your hydration status and help get more carbs in.

Lastly, a very common and useful strategy before a long run is to have a final top-up of fuel 5-15min before you start. This should be about 20-30g of carbs, so a gel, chews, sports drink, or something along those lines are great options.

4. What are the Best Carbohydrate Sources for Sustained Energy During a Long Race?

Go for easy-to-digest, simple carbs that will give you quick energy during a race. Even if you’re running an ultra, this isn’t a time for fiber-rich complex carbs. 

Here are some common carb-rich foods and fluids that are particularly popular at ultra-endurance events:

Sweet:

• Gels, chews, sports drinks, fig bars, applesauce, smoothie pouches, gummies, coke, Ginger Ale, cookies, dates, PB&J, watermelon/other fruit

Salty/savory:

• Pretzels, chips, mashed potatoes, quesadilla, turkey sandwich, salted PB sandwich, plain bagel, broth, chicken noodle soup, rice balls, boiled potatoes with salt

As we already discussed above, what you eat BEFORE also is very important to sustaining your energy levels during a race. Carb loading and eating a carb-rich pre-race meal will help prolong your glycogen (energy) stores and allow you to perform better for longer on race day.

5. How Frequently Should You Eat or Drink to Maintain Energy Levels? 

How frequently you should eat or drink depends on many different factors, including your sweat rate, intensity level, duration of your event, individual GI tolerance, intake goals, products you're using, and more.

Typically, most athletes consume calories (primarily carbs) every 15-45 minutes, and more commonly in the 20-30min range for endurance events.

For example, let's say you are trying to hit 60g of carbs per hour. If you’re using 30g gels and not taking in carb-containing fluids, then 1 gel per 30min is a good cadence.

If you’re using 22g-25g gels, then you need to take them more frequently.

If you’re taking a 40g or 50g gel, then you may choose to take half the gel more frequently, or perhaps you decide to aim for a higher goal per hour (60g is on the low end for endurance athletes). 

For fluids, I highly recommend that you test your sweat rate to determine your individual fluid losses. This will help you identify a personalized fluid target in ounces per hour to drink during your race, which you can practice during training and adjust based on the weather (warmer temps mean higher sweat losses).

Typically, it’s recommended to drink on a schedule and not wait for thirst, which is a late sign of needing fluids. You will also want to consider if you’re carrying water or relying on aid stations to drink.

Once you figure out your goal fluid intake, sip regularly across the hour to achieve that goal. Keep in mind that certain gels require fluid with them while others do not, and remember that you also need to be replacing electrolyte losses (more info on that here).

6. What’s the Ideal Post-Race Nutrition Strategy for Recovery?

Recovery is complex and involves nutrition, sleep, rest, and life stress. It’s not as simple as throwing back a protein shake and calling it a day!

Here are the primary nutrients that you need shortly after finishing a race:

• Fluids and salts to replace what you lost to sweat

• Carbs to replenish your energy stores

• Protein to repair and rebuild your muscle tissue

If you're building a recovery meal, then you should also include healthy fats to help absorb all the nutrients you're eating, help meet increased energy needs, and reduce inflammation (i.e. Omega-3 fatty acids). You also want fruits and veggies (i.e. "color") to provide a variety of micronutrients and antioxidants, as well as fiber.

Timing is very important when it comes to recovery nutrition - is not just a box that you tick. Recovery is an ongoing process!

You can divide recovery nutrition into two phases:

• Immediately after exercise (you've probably heard about this one the most)

• The rest of the day and beyond (this one is equally important)

Typically, it's recommended that you refuel within 60 minutes of finishing exercise. The door to recovery doesn’t slam shut, but it makes sense to refuel within an hour, or as close to this time frame as possible, after a race. Your body is well-primed for nutrition given you just depleted yourself, and it's ready to replenish, rehydrate, and repair. 

Like with anything, the details of an “ideal” post-race nutrition plan must be customized to your needs and preferences. 

As a general starting point, try to drink 16-24oz of fluid after your run, preferably with carbs and electrolytes. Fluid and sodium targets for rehydration should be individualized because losses depend on sweat rate, sweat composition, weather, altitude, and exercise duration and intensity.

If you know your sweat rate, aim to drink 125-150% of your losses, or 20-24oz per lb that you lose. Try to finish drinking this amount within a few hours.

Nutrition guidelines for recovery differ based on what you just did and how much time you have until your next long or hard session. Essentially, the less time you have to recover, the more aggressive you need to be with your nutrition, especially with replenishing your carb stores. 

Here are some guidelines for carbs and protein based on bodyweight post-workout, when you have at least 12 hours to recover:

• 1g/kg carbs AND

• 0.5g/kg protein

Your personal protein and carb needs depend on many different factors, including your weight, age, training volume, and performance and fitness goals. Also consider the overall context of what you need as an endurance athlete per day. But these recommendations give you a good starting point!

Immediately after a race, consume easy-to-digest, lower fiber carbs to quickly restock your glycogen stores. The less time you have to recover, the more important this becomes. Then 1-2hr onwards, you can consume more fiber-rich carb sources like whole grains, beans, etc. 

Leucine, a branch chain and essential amino acid, plays a key role in muscle building and should be present in whatever protein you choose. Aim for 1-3g of leucine in your recovery meal, which you’ll get if you consume 20-40g of protein from most animal and certain plant based proteins.

There are no specific weight-based guidelines for recovery when it comes to fats. Your needs depend on how much energy you require per day and other factors. However, fat is a very important macronutrient, and a key component of your recovery meals and snacks.

Fruits and vegetables are another critical part of your recovery meals and snacks. They contribute much-needed micronutrients, antioxidants, and fiber, all of which impacts recovery and general health.

Polyphenols, which are found in many brightly colored fruits like blueberries, have high levels of antioxidants as well as anti-inflammatory qualities. They may help reduce muscle soreness, improve performance, benefit gut health, and help with sleep.

Here are three fueling strategies you can use to hit your post-run carb and protein goals:

1. Have a full meal hitting your nutrition targets within 1 hour

2. Have a simple shake or snack with protein and carbs immediately after exercise, followed by a balanced meal 60-90min later

3. Have a nutrition-packed smoothie plus carb-rich solid food within 1 hour 

If you're not sure which strategy is best for you, consider your running and eating schedule, access to solid food, appetite, and food preferences. The second strategy using liquid nutrition first is very useful if you struggle to eat right after exercise or you have to travel back home and need something quick and easy.

Read more about recovery nutrition in detail in this article.

If you enjoyed this article and would like to learn more, Claire has many free nutrition resources including downloads on a wide range of everyday and performance nutrition topics at www.eatforendurance.com.