What do irregular bowel movements, food sensitivities, exercise-induced loose stools, and constant bloating after meals have in common? Two things, actually! 1.) These symptoms aren’t normal and should not be dismissed, and 2.) These symptoms are frequently related to underlying gut issues.
In my nutrition practice, I meet outdoor athletes daily who struggle with gut issues and have accepted that these symptoms are “normal” and part and parcel of their daily lives. In fact, these symptoms deserve focused attention, testing, and treatment. If your gut health is a mess, it will be hard, if not impossible, to achieve the level of health and performance you desire in your life.
In this blog, I’ll discuss the connections between gut health, whole-body health, and athletic performance and explore how gut testing can help you up-level your well-being and athletic experience!
Table of Contents
Your Gut: The Foundation of Health and Performance
The gastrointestinal system, often referred to simply as your “GI system” or “gut” (I will use these two terms interchangeably in this blog), plays numerous and profound roles in your physiology.
In fact, in the functional nutrition paradigm, which you can read about here, a healthy gut is essential for whole-body health and optimal physical, mental, and emotional function.
Your gut health (or lack thereof) significantly impacts the following aspects of your well-being and athletic performance:
Digestion and absorption of nutrients: Digesting and absorbing nutrients from your food is absolutely vital for fueling your body in daily life, not to mention during training and racing. Nutrient availability also affects how your body repairs and recovers after exercise.
Immune function: Your gut is home to a significant portion of your immune system, and an increasing body of research shows that gut health affects immune function. An unhealthy gut is associated with an increased risk of infections and autoimmunity. (Source, Source, Source)
Mood and mental health: An abundance of research demonstrates the connection between the gut and mental health. Gut imbalances are associated with an increased risk of depression and anxiety. (Source)
Energy: Gut imbalances may drive fatigue by impairing digestion and absorption of key energy-supporting nutrients like iron and vitamin B12, causing chronic inflammation (which can drain your energy), or even disrupting hormones such as thyroid hormones. (Source, Source, Source, Source)
Blood sugar control: Your ability to maintain balanced blood sugar is affected by your gut.
Cardiovascular health: Gut imbalances are linked to high cholesterol and cardiovascular disease. (Source, Source)
Body weight and composition: The gut may impact body weight and body composition through its effects on calorie absorption from food, inflammation, and hormones. (Source, Source)
Endurance, muscle recovery, and exercise capacity: The gut and overall gut health (or lack thereof) are linked to endurance, muscle recovery, and exercise capacity, thus impacting your overall athletic performance. (Source, Source)
As you can see, your gut is involved in many processes that affect your health and physical functioning. The keystone aspects of health mentioned above (digestion, absorption, mood, immune function, etc.) are prerequisites to training and performing well as an athlete.
If your gut health is a mess, it will be hard, if not impossible, to achieve the level of health and performance you desire. This is why it is so crucial to get your gut health in check if you’re struggling with symptoms. I guarantee you will feel and function better as a human being and an athlete when your gut is healthy!
Common Gut Symptoms in Active Individuals:
Loose stools before, during, or after running
Constipation (defined as not having a bowel movement daily. A healthy GI system should produce at least one well-formed daily bowel movement.)
Frequent bloating after meals or bloating that gets worse over the course of the day
Food sensitivities
Reflux
Frequent burping
In addition, problems in the gut can manifest in other parts of the body, potentially causing problems such as:
Acne
Eczema
Rosacea
Menstrual cycle difficulties
Sleep issues
Brain fog
Low mood
What Most Sports Dietitians/Nutritionists Get Wrong About Gut Health
On social media and on podcasts, I commonly see sports dietitians attribute athlete gut issues to just a few factors:
Overeating sugar, mainly simple sugars from sports nutrition products.
Not hydrating sufficiently.
Not “training” the gut to tolerate certain types and volumes of sports nutrition products and foods before training and racing.
While these factors can contribute to gut issues, they are not the only factors compromising athlete gut health. In fact, for some athletes, these issues are just the tip of the iceberg. It takes a sports nutritionist who is highly trained in GI health and has worked with many people with GI issues to understand how to address and improve stubborn athlete gut issues.
What’s Really Going on with Your Gut Health?
In my work with hundreds of clients, including outdoor athletes, I’ve noted that the following gut issues are common:
Gut dysbiosis: Gut dysbiosis is an imbalance in the gut microbiota, the community of microbes that live in your intestines. A conventional gastroenterologist cannot identify gut dysbiosis with standard tests such as stool cultures or a colonoscopy. To identify this issue, we need to use a functional stool test (more on this shortly).
Small intestinal bacterial overgrowth (SIBO): SIBO is a condition where an abnormal number or type of bacteria grow in the small intestine, leading to symptoms like bloating, gas, diarrhea, or constipation. It can disrupt digestion and nutrient absorption, affecting overall gut health. In many cases, a person who was told they have IBS may actually have SIBO. (Source)
Increased intestinal permeability (aka “leaky gut”): Leaky gut is a condition where the lining of the gut becomes too permeable, allowing undigested food particles, toxins, and bacteria to pass into the bloodstream. This can lead to inflammation and may contribute to various health issues, including autoimmunity and musculoskeletal injuries. (Source, Source)
Gluten and dairy sensitivities: Dairy and gluten sensitivity are the two most common food sensitivities in my practice that can cause significant gastrointestinal symptoms, including diarrhea, constipation, bloating, excessive gas, heartburn, and reflux. Removing these foods for 4-6 weeks while working to improve gut health via testing and an evidence-based gut protocol can significantly improve gut symptoms and overall gut function.
Before you get all up in arms and say that “only people with celiac disease are gluten-sensitive,” you should be aware that there is an ABUNDANCE of research indicating the reality of non-celiac gluten sensitivity. (Source)
FODMAP sensitivity: Difficulty digesting certain types of carbohydrates known as FODMAPs (Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols). These compounds are found in various foods and can ferment in the gut, causing symptoms like bloating, gas, diarrhea, or abdominal pain, especially in people with conditions like SIBO and IBS (Irritable Bowel Syndrome).
How Do Gut Issues Develop?
Clients often ask me how or why they have gut issues. While I can’t directly answer this question, I tell them that many factors can interfere with healthy gut function throughout life.
Some of these factors include:
Antibiotics: Decreases levels of beneficial gut bacteria and disrupts the healthy balance of microbes in the gut
Hormonal contraceptives: Hormonal contraceptives are associated with adverse changes in the gut microbiota and gut inflammation. It is possible that the longer you’ve taken hormonal contraceptives, the more potential there is for gut dysbiosis. (Source, Source)
For more information about hormonal contraceptives and the gut, check out this blog by Jolene Brighten.
Stress: Stress can increase the growth of harmful gut bacteria and reduce beneficial bacteria.(Source)
NSAIDs: Non-steroidal anti-inflammatory drugs can promote leaky gut, especially when used in excess (which is common amongst athletes). This may be due to the toxic effect of NSAIDs on intestinal cells. Yikes! (Source)
Ultra-processed food: A diet heavy in processed foods, including added sugars and other refined carbohydrates like white bread and cereal, is connected to gut dysbiosis. (Source)
Exposure to pesticides and herbicides: Exposure to agricultural chemicals via residues on our food may negatively impact our gut health. This is one reason I’m a big proponent of choosing pesticide- and herbicide-free produce or conventional produce that is low in chemical residues. (Source, Source)
Excessive exercise: If you’re reading this article, chances are you’re an athlete and love training! However, intense training can cause gut issues for some people by disrupting the intestinal lining and causing inflammation. High temperatures, fluid restriction (aka dehydration), and high altitude may exacerbate exercise-induced leaky gut. (Source)
Enhance Your Health and Performance with Gut Testing
There are some gut tests that I refer clients to their providers for, such as the small intestinal bacterial overgrowth (SIBO) test and celiac disease testing. It is possible to get these tests covered by insurance, so I prefer to have clients go this route if their doctor is open-minded about testing.
However, as a functional sports nutritionist, I am also qualified to order and interpret a variety of gut tests based on my training.
Here are several of the gut tests that I use with athletes in my nutrition practice:
GI MAP: This is a comprehensive functional stool test that uses the PCR (DNA) method to analyze gut dysbiosis, digestive enzyme production, parasites, candida/fungal overgrowth, pathogenic bacteria, viral infections, healthy gut bacteria products (short-chain fatty acids), leaky gut, detox function, and H. pylori.
IBSSure (anti-vinculin antibody testing): Assesses for the antibodies associated with post-infectious Irritable Bowel Syndrome (IBS), or IBS, that occurs after a bout of food poisoning. Identifying these antibodies helps to plan and optimize gut protocols, especially during maintenance phases.
Wheat/Gluten Sensitivity and Intestinal Permeability Testing: This test provides a detailed assessment of wheat and gluten reactivity/immunity, including Celiac, non-celiac, and wheat protein sensitivity. It also includes LPS antibodies (which provide a detailed assessment of intestinal permeability or ‘leaky gut’).
What will a GI MAP test show you? Here are several pages from a sample GI MAP report:
The GI MAP shows whether harmful microbes are present, the balance of beneficial bacteria (or lack thereof) in the gut, and markers of intestinal health, inflammation, and digestion.
I offer each of these labs in my nutrition practice and get great results when I use these tests with my clients!
If you decide to do a gut test like the GI MAP, it is crucial to work with a nutritionist who is trained in and experienced with using the test. I’ve seen some dietitians and other healthcare providers order the test and not know what to do with the results, leaving their clients in the lurch.
Example interventions within my scope of practice that I use to help athletes improve their gut health include:
Supplementation protocols for SIBO (can be done alongside antibiotics from your doctor if you choose to go the antibiotic route), including evidence-based herbs, probiotics, and digestive supports
Probiotic and prebiotic protocols for improving low beneficial bacteria
Dietary interventions and supplement protocols for improving leaky gut
Short-term elimination diets to address chronic gut symptoms such as loose stools, constipation, and bloating
These are just a few examples of the tools in my “toolkit” that I use to help active individuals overcome their gut symptoms and feel and perform their best!
The Bottom Line on Gut Health and Athletic Performance
Taking care of your gut is about more than just avoiding digestive discomfort—it’s about supporting your overall health and maximizing your performance. From nutrient absorption to inflammation control, your gut plays a vital role in how your body functions and recovers. By using the right tests to identify gut problems, addressing imbalances, and implementing evidence-based gut protocols with the guidance of an experienced nutritionist, you can build a strong foundation for both everyday wellness and peak athletic performance.
The content provided on this nutrition blog is intended for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay seeking it because of something you have read on this blog.
The information and recommendations presented here are based on general nutrition principles and may not be suitable for everyone. Individual dietary needs and health concerns vary, and what works for one person may not be appropriate for another.
I make every effort to provide accurate and up-to-date information, but the field of nutrition is constantly evolving, and new research may impact dietary recommendations. Therefore, I cannot guarantee the accuracy or completeness of the information presented on this blog.
If you have specific dietary or health concerns, please consult a qualified nutritionist or another healthcare professional for personalized guidance.
I empower others through nutrition to conquer their mountain adventures, drawing from my own experiences.
With a background in Biomedical Science and an M.S. in Human Nutrition, I’m a Certified Nutrition Specialist and Licensed Dietitian Nutritionist. My journey in functional medicine has equipped me to work alongside athletes and tackle complex health cases. As a passionate trail runner, backcountry skier, and backpacker, I strive to support others on their paths to peak performance and well-being.
