Training the Gut for and during Long Runs and Endurance Sports

Now that it’s full on summer, let’s check in about a topic that is pertinent for all the endurance athletes, and particularly runners, with wonky guts and/or rigid beliefs about fueling during longer efforts. 

I’ve heard so many variations on the following over my years as a runner:
“I can’t eat anything before a run, ever.”
“I can’t eat anything during a run.”
“ I can’t drink anything more than a little water during a run.”
“I have no appetite for hours (or days) after a run and my GI is messed up for several days.”
“I’m not recovering from long runs or races as well as I used to.”

If you currently relate to any of those statements, I want you to know that the digestive system is highly adaptable. Gastric emptying as well as stomach comfort can be ‘trained’ during endurance activities.

Stored glycogen, or the amount of carbohydrates in our system already, are depleted after about 80 minutes at marathon pace, so for most athletes training for longer efforts, fueling with some sort of carbohydrate during exercise is essential. This training of the gut can improve the delivery of nutrients during exercise so during these long efforts, your system gets the fuel you need and are ingesting, and alleviates some (and perhaps all) of your negative GI symptoms.

How Can I Train my Gut? 

What we currently know is that the stomach can adapt to ingesting large volumes of  both solids, fluids, or combinations of the two. 

Just think about those competitive eaters who can down dozens of hot dogs in a matter of minutes. Disgusting thought, I know, but they have to train their systems to do it!  For endurance athletes needing fuel for the long run, we need to do our own version of gut training. 

This happens both during and outside of exercise because eating a higher carbohydrate diet leads to our intestinal cells, called enterocytes, being able to absorb and utilize carbohydrates as fuel more efficiently. 

To get sugar (carbohydrates) from our small intestine where absorption occurs into our blood, the sugar molecules mostly have to be transported across the membrane by glucose or fructose transporters. Think of a taxi transporting you from the airport to your destination. When we eat a diet high in carbohydrates, our body naturally increases the number of sugar taxis (glucose and fructose transporters). 

You’ll notice some of these taxis are sodium-dependent, which is a super essential nutrient for endurance exercise, particularly in the summer, but a topic for another day. 

We also know that increasing dietary intake of carbohydrates increases the rate of gastric emptying. This occurs rapidly with a change in diet, within just a few days. So what this means is that you can fuel with more carbohydrate before exercise, fuel with more carbohydrate during exercise, not feel like you’re running around with a giant, full, sloshy gut, and perform the training run or race better, because you were using the fuel you needed to perform adequately. 

And, we also now have evidence that when you fuel with the appropriate amount of carbohydrates before, during and after an exercise bout, recovery from hard efforts is substantially improved. 

When your body has all the sugar taxis it needs to get carbohydrates out of the digestive system and into the blood stream for circulation and use as fuel as quickly and efficiently as possible, and our body gets used to using carbohydrates added on the go as fuel, the chances of developing GI complaints during exercise are much smaller.

Win, win, and win, in my opinion. 

How Much Carbohydrate Can and Should I Be able to Tolerate ?

How much carbohydrates you need or should consume during exercise depends on a few factors. One, how long you’re going to be out there. Two, the intensity of the effort. And three, your gender. 

Exogenous carbohydrate oxidation, or the amount of carbohydrates we can use during exercise, peaks around 60 grams per hour when it comes from glucose only.  When fructose is ingested in addition to glucose, carbohydrate oxidation rates are elevated above 60 grams per hour, to 90 to 120 grams per hour (when the gut has been trained). In women, however, we have evidence that carbohydrate oxidation rates appear to be maximized at about 60 grams of carbohydrates per hour (2). If you’re a female and looking to maximize your fueling and racing/recovering capacity, you can experiment with ingesting more than 60 grams per hour. This upper limit will likely be individual.

The current guidelines for fueling are to take in up to about 60 grams per hour of carbohydrates for exercise lasting up to two hours. 

And when the effort lasts longer than 2 hours, men should experiment with increasing their intake to slightly greater amounts of carbohydrate (90g/hr), but women may feel best at sticking with 60 grams per hour. These carbohydrates should be a mix of glucose and fructose or maltodextrin and fructose. Virtually every sports nutrition product for use during exercise includes a mixture of carbohydrates these days so most people will not need to worry about getting the different sources. And most do-it-yourself whole food fuel sources will also include both fructose and glucose. 

Note that sucrose, which is contained within many whole foods and is also what makes up simple table sugar, is a disaccharide, meaning it has two different sugar compounds, fructose and glucose.

Here’s another way to look at the timeline of fueling needs:

Exercise Duration0-59 minutes1 hour2 hours2.5 hours3 hours
Grams of Carbohydrate Per Hournone3030-60g : women
Up to 70 g/hr: men
(higher intensity = higher need)
30-60g : women
Up to 70 g/hr: men
60 g: women (can experiment with more)
Up to 90 g: men
(can experiment with up to 120 g)

How Long Does Training the Gut Take? 


If you’re training for a race and practicing fueling during long efforts, it doesn’t take more than a few days to a couple weeks to increase those sugar taxis in your gut. Based on animal data, an increase in dietary carbohydrate from 40 to 70% could result in a doubling of SGLT1 transporters over a period of two weeks (1).

But it’s important to practice your race nutritional strategy in training, get used to higher volumes of solid or liquid intakes, and higher carbohydrate intakes both during and outside of training. 


As always with fueling for sports, it will take a little individual experimenting and tweaking to find what works for you so you’re less likely to end up looking like this during your next long run or race:

Will Training My Gut Fix all my Exercise-Related Digestive Woes? 

Perhaps following the above recommendations will be a simple answer to fixing all your exercise-caused angry/sad midsection woes. 

But many people with digestive systems that are more prone to upset also need to pay special attention to what you are and aren’t consuming, and how much you’re eating in all the hours outside of training. This can be very individual. 

Want to Know More?

Within my nutrition practice, I specialize in digestive imbalances. Often when we’re experiencing chronic GI distress, fatigue, and/or malabsorption of foods and nutrients, there will be imbalances in several systems of the body simultaneously. I shared more about this topic in the nervous system’s role in part 1, the immune response and subsequent inflammation in part two, gut microbes and dysbiosis in part three and the importance of chewing our food in part four. Check those out or reach out to me for more personalized support for gut healing, or to go from not being able to tolerate fueling, to training your gut for the amount you need.

References:

1). Jeukendrup, A.E. (2017). Training the Gut for Athletes. Sports Medicine, 47(Suppl 1): S101-S110. https://doi.org/10.1007/s40279-017-0690-6  
2). Wallis, G.A, et al. (2007). Dose-response effects of ingested carbohydrate on exercise metabolism in women. Medicine and Science in Sports and Exercise, 39(1): 131-8. https://doi.org/10.1249/01.mss.0000241645.28467.d3. 

Strawberry Crumble

and Sustainably Attaining Healing + Health

I’ve been reflecting lately on healing and health – how some of us are ‘gifted’ with easy and good health, and easy and quick recovery from running and workouts for most of our lives…and then for some of us, health is a multi-faceted journey, a ‘getting to’ figure out what the nugget(s) of wisdom are underneath the sometimes long periods of pain, struggle, fear, disease, injury…

I certainly don’t have all the answers. But I know that finding and immersing yourself in what brings you joy, eating more foods that still look like they came from the ground/earth, and learning to set aside some of your hurry and worry helps a whole lot in the process.

I could give more details about eating colorful and anti-inflammatory foods, specific nutrients, etc. for sustainable and lasting healing.

But today, I’ll offer encouragement that is a little more abstract. Because finding what makes you feel whole and healthy long-term, what brings you joy and makes you feel like your most authentic self will always be worth pursuing.

If you’re in the thick of your own complicated health journey, don’t give up hope. Focus on finding what brings you joy. See if you can begin by eating your next meal, whatever it is, in a way that makes you grateful for everyone (people and all the other creatures) involved in getting it to you.

Strawberry Crumble
Prep + Cook: 60 minutes | Makes: 4-6 servings

I shared this recipe in a virtual cook-along with a few of my local Oiselle Volée running teammates this week and it was a big hit. It brought so much joy to me, and hopefully them, to share and bake it in community. Everyone loved the little pop of lemon this contains. The addition of the slight hit of acid enhances all the other flavors. This is also a great sweet dessert for individuals who are following a gut-healing dietary pattern. It contains only a little added sugar, which is highly inflammatory and problematic for gut-healing, but lots of flavor. Hope you enjoy!

Filling:
1 pound / 4-6 cups fresh strawberries
2 teaspoons fresh lemon juice
1-2 teaspoons lemon zest
½ teaspoon vanilla extract

Crumble Topping:
1 cup / 100 g rolled oats
⅓ cup / 37 g almond flour or ⅓ cup raw sunflower seeds, ground into a meal
¼ teaspoon salt
½ teaspoon ground ginger
½ teaspoon turmeric
1 teaspoon vanilla extract
¼ cup /55 g coconut oil, ghee, or butter
2-3 tablespoons / 36 g sugar

  1. Preheat the oven to 350°F. Place the berries in a 8 x 8-inch baking dish or similar, and toss with ½ tsp. vanilla, lemon juice and lemon zest.
  2. Prepare the crumble in a separate bowl. Start by mixing oats, almond or sunflower flour, salt, spices, and vanilla.
  3. Then add the coconut oil and sugar. Use a spoon or your hands to mix until combined. With your fingers, crumble the filling evenly over the berries.
  4. Bake in the oven for 30-35 minutes until the fruit juices are bubbling around the edges and the topping is golden brown.

    Notes:
    Change up the berries depending on availability and season. Some berries might require 1-2 Tbs. of maple syrup or sugar added to the filling. If using frozen berries, thaw and drain the excess liquid before using. 
a couple shots of the last batch in the vibrant, bright morning light

What Does a Balanced Meal Look Like?

How to Make a Balanced Meal  

One of the things I hear on repeat is that ‘meals just don’t taste good’ which often leads to dissatisfaction in a number of ways. Your taste buds aren’t satisfied so you reach for more even after you’re no longer hungry, nibbling on this and that and ultimately being dissatisfied and frustrated at overeating — or in some cases, undereating — because of it. 

OR

You’re needing to eat a certain way to heal your digestive system, but “it’s so boring” and “it just doesn’t taste good.” And you resist the healing effect that should be taking place.   

OR

You want to eat intuitively, but you’re overcome by cravings for “junk foods” and comfort foods and simply don’t want to eat “healthy foods.”

The Balanced Plate

One of the best ways to solve a lot of the problems listed above is to build meals that are balanced. This means your meal includes the six primary flavors of sweet, salty, sour, bitter, pungent, and astringent

But it also means there’s a balance of those flavors, in the ideal-for-you proportions. A way that tends to be both nutritious and simple to apply is dividing those six flavors into categories of building and lightening foods. 

You can ask the question of each food ingredient, will this build my body or lighten it?, to help you.

Here’s a good list:

Building Foods (comprising the flavors of sweet, sour, and salty)
Whole Grains
Sweet Vegetables (often root vegetables)
Dairy
Oils
Sweeteners
Fruit
Animal Protein

Lightening Foods (comprising pungent, bitter, and astringent flavors)
Beans and Legumes
Nuts and Seeds
Green Vegetables
Spicy/Bitter/Pungent Vegetables – such as radishes, horseradish, spicy turnips, onions, garlic, and hot/spicy peppers, eggplants
Fresh Herbs
Spices

An Ideal Ratio for Your Balanced Plate

What’s an ideal ratio of building and lightening foods? This can depend on the person, but not as much as you might think. For most, aiming for a ratio of 60% building foods and 40% lightening is ideal.
In the process of doing this, you’ll also nearly always incorporate the six flavors, and meals start to taste better, you enjoy them more, and you notice that you’re feeling satisfied without reaching for more — or struggling to eat because nothing tastes good. 

Omnivore Balanced Plate

To make a basic meal that contains meat or eggs, it’s good to think about splitting the 60/40 ratio into the different components. I recommend 20% meat or eggs, 20% whole grain, and 20% sweet vegetables, like carrots, peas, or zucchini. Then the 40% can be mostly leafy greens, like romaine lettuce with a drizzle of vinaigrette dressing, a small handful of chopped nuts or seeds, and a pinch of fresh basil or mint.
When you add in the oil/fat, spice and seasoning components, depending on your preference for the meal, it will be complete, satisfying, and balanced. 

Plant-Based  or Vegan Balanced Plate

To make a basic meal that’s free from most animal products, split your 60/40 ratio into a whole grain, a sweet vegetable, a legume, and a green/astringent vegetable. Start with 30% whole grain, and 30% sweet vegetables, like any of the examples above or fennel, sweet potato, or corn. Then the 40% can be split between 20% legume, tofu, or tempeh, and 20% leafy greens, like cabbage with a nut-based dressing, and a pinch of fresh basil or mint.
When you add in the oil/fat, spice and seasoning components, depending on your preference for the meal, again, it will be complete, satisfying, and balanced. 

One Idea, Many Variations

The beauty of this Balanced Plate idea is that ultimately, it can apply to any type of food, cuisine or flavoring profile. It worked out just fine when I made a Lasagna, rolled up ingredients into a Sushi Burrito, make homemade Pizza, pasta or noodles, and more.

It also helps to keep this idea in mind when you’re eating out. When your preferred dish on a menu isn’t quite as balanced as this, is there a way to make it a little more so by choosing a specific side or leaving off/adding something? 

But I’m an athlete training for a race and need lots of food! Does this balanced meal ratio apply?

Yes, it does! There are two frequent meal scenarios that athletes tend to get into before recovery or performance starts to suffer. Either there’s not enough of the lightening / green vegetable component to most meals OR there’s too much of it, and not enough of the whole grains, root vegetables and (for plant-based athletes), beans or legumes. If you think one of these might apply to you, see if you can add in more of what’s missing, and see how you start to feel. 

One Final Caveat

These percentages are not meant to be exact or obsessively measured. When you look at your plate, does about 60 percent of it contain a grain, sweet root vegetable, and maybe an animal protein or dairy? And does about 40 percent of it look like it’s green vegetables and maybe beans and a sprinkle of toasted nuts? That’s what we’re aiming for here. 

When you begin to eat more meals that have a balance of the flavors in ideal proportions, you’ll also notice that ongoing digestive symptoms may begin to reduce and eventually go away. And because meals simply taste better without being elaborate or extra complicated, cravings and over- or under-eating begins to be less of an everyday issue.

Much of my nutrition practice is focused on individuals and athletes with digestive health issues such as leaky gut, food allergies and intolerances, chronic GI distress, malabsorption of foods and nutrients, and inflammation. If you’re tired, stressed, and not really sure what to eat to help or hurt anymore, I invite you to reach out to me for more personalized support.