The Top 3 Causes of Autoimmunity in Athletes & Active Individuals

When thinking of the typical picture painted around autoimmunity, it often doesn’t match the reality of many active individuals and athletes. Maybe you eat healthy, train consistently, prioritize hydration, and “do everything right,” yet you have elevated autoimmune antibodies, chronic fatigue, digestive symptoms, and hormone imbalances. For many high-performing individuals, this disconnect can feel incredibly frustrating and confusing.

So why does autoimmunity develop in people who appear healthy on the surface? Often, the answer lies in “energy leaks” – hidden stressors that gradually drain the body’s capacity to recover, adapt, and maintain immune balance over time.

Find out your top energy leak in our free quiz, linked here.

The Connection Between Exercise, Stress, and Autoimmunity

At its core, autoimmunity is often a sign that the immune system is under stress. Exercise itself is not the problem. However, when paired with chronic under-recovery, gut stress, immune dysregulation, oxidative stress, and nutrient depletion, it can gradually push the body into a more inflammatory and immune-reactive state.

While intentional movement can absolutely support health, mitochondrial function, and insulin sensitivity, there is also a threshold where exercise becomes another physiological stressor the body must adapt to. When exercise tolerance is low, the priority becomes addressing the underlying immune dysregulation first – then reintroducing exercise strategically as a tool to rebuild metabolic and mitochondrial health. Let’s explore three of the most common root causes driving autoimmunity in athletes and highly active individuals.

#1. Gut Dysfunction and Increased Intestinal Permeability

The gut plays a central role in immune regulation, and increased intestinal permeability (“leaky gut”) is one of the most well-established contributors to autoimmune disease.

What many athletes don’t realize is that high-intensity or long-duration endurance exercise (especially in hot temperatures) can temporarily increase gut permeability, especially when paired with poor intra-workout fueling strategies.

During intense exercise, blood flow is redirected away from the digestive tract toward working muscles. Over time, this can stress the gut lining and contribute to increased permeability, digestive symptoms, food sensitivities, and immune activation.

Additional triggers like gluten consumption, glyphosate exposure, bacterial overgrowth, H. pylori, or chronic stress can compound this process further.

This is one reason why fueling around exercise matters so much. The proper carbohydrate to fat intake ratio before and during training helps reduce excessive cortisol (stress hormone) output and support optimal digestion during exercise.

If you are dealing with GI symptoms, it’s important to investigate potential underlying gut infections, dysbiosis, and inflammatory triggers while simultaneously supporting gut repair with supportive nutrients and demulcent herbs.

#2. Oxidative Stress and Redox Imbalance

Moderate to high intensity exercise naturally increases oxidative stress, or free radical buildup in the body. This is not inherently bad, it is essential to the positive adaptations of exercise. 

Problems arise when oxidative stress levels outweigh the body’s antioxidant capacity – both what we produce within the body (endogenous antioxidants) and what we consume (exogenous antioxidants).

Active individuals often have significantly higher nutrient and antioxidant demands due to increased mitochondrial activity, higher metabolic turnover, and micronutrient losses through sweat. If antioxidant defenses become depleted, oxidative stress can begin damaging tissues, impairing recovery, and increasing inflammatory processes.

This is where redox balance, the balance between free radicals and antioxidants, is critical. The goal is not to eliminate oxidative stress completely, but rather to ensure the body has enough total antioxidant capacity to appropriately respond and recover.

This is also why underfueling can be so problematic for athletes with autoimmunity. Chronic low energy availability decreases nutritional intake of these key antioxidants and reduces the body’s ability to generate antioxidants like glutathione that help maintain immune tolerance.

Autoimmune processes themselves further drive oxidative stress and redox imbalance, as do many root causes of autoimmunity and immune dysregulation, such as mold exposure, gut dysbiosis, and high viral load or chronic infections.

To get oxidative stress back in check, improving nutrient density, recovery capacity, and antioxidant status is critical, alongside assessing exercise programming, modifying training accordingly, and addressing additional underlying drivers of immune dysregulation.

#3. Mitochondrial Dysfunction and Energy Deficiency

Mitochondria are the energy-producing centers within the cell, and they sit at the center of both exercise performance and immune health.

The right amount of exercise can strengthen mitochondrial function and improve energy and metabolism. However, excessive training without adequate recovery and nutrition can create the opposite effect.

When the body enters a prolonged energy deficit, mitochondrial stress can trigger what is known as the cell danger response. This is a protective survival state resulting in a downshift in mitochondrial function, reduced energy production, increased oxidative stress and inflammation, and immune overactivation. This immune hyperreactivity can worsen autoimmune processes.

This is often why some individuals with autoimmunity feel significantly worse with movement, an increase in cardio, high-intensity interval training, or even heat exposure like sauna. The body does not have the capacity for this additional mitochondrial stressor due to micronutrient insufficiencies and immune dysregulation dampening mitochondrial function. 

Next Steps for Root Cause Healing of Your Autoimmunity

Autoimmunity is rarely caused by one single factor. More often, it is the accumulation of multiple energy leaks overwhelming the body’s ability to maintain resilience. This is why proper testing and individualized investigation matter.

In our practice, we often assess:

• Gut health and microbiome balance
• Nutrient deficiencies and immune-supportive micronutrients
• Mitochondrial function and energy production
• Oxidative stress and antioxidant status
• Viral load and chronic immune activation
• Hormones, thyroid function, and adrenal health

If you don’t know where your energy leaks may be coming from, start with our free quiz to identify your top one. Then explore deeper root-cause investigation. In our 1:1 coaching program, we take a comprehensive root-cause approach to autoimmunity, investigating underlying drivers of chronic inflammation and immune dysregulation.