Are MREs Hard to Digest? Separating Fact from Military Folklore

December 17, 2025 •

4 min read

According to a 2019 study by the U.S. Army Research Institute of Environmental Medicine, Meals, Ready-to-Eat (MREs) do not negatively impact gut health or increase intestinal permeability in a controlled environment. The myth surrounding why MREs are hard to digest is often more complex than just the food itself.

Quick Summary

This article examines the science behind MRE digestibility, contrasting common anecdotes with research findings to identify true culprits like dehydration and stress, rather than the MRE content alone.

Key Points

MREs aren't inherently bad for digestion: Army studies found no significant negative impact on gut health when external factors were controlled.
Dehydration is a major cause of issues: The high sodium content in MREs and insufficient water intake frequently lead to constipation in the field.
Low fiber content contributes to constipation: MREs are low in fiber, so consuming all fibrous components like crackers is vital for regularity.
Environment matters more than the food: High stress, physical exertion, and poor sleep patterns are significant contributors to GI distress.
Processed ingredients can cause sensitivity: Additives like xanthan gum and MSG can lead to bloating or discomfort in sensitive individuals.
Supplementation helps: For prolonged MRE consumption, adding fiber or probiotics can help maintain a healthy gut microbiome.
Context is key: Short-term MRE use is effective, but long-term consumption requires active management of hydration and nutrition to avoid digestive discomfort.

The 'Meals, Refusing to Exit' Myth vs. Reality

For decades, soldiers have joked that MRE stands for "Meals, Refusing to Exit" due to widespread anecdotal reports of constipation. This persistent humor suggests a universal digestive problem with military rations. However, scientific research presents a more nuanced picture. A key 2019 study involving volunteers consuming MREs for 21 days found no evidence of negative gut health impacts or increased 'gut leakiness' when other environmental factors were controlled. Instead, the study's author pointed to external stressors like high-stress field conditions, dehydration, and disrupted sleep as more likely causes of GI distress. The perception that MREs are inherently bad for digestion stems from conflating the food's properties with the harsh realities of the operational environment.

Nutritional Factors That Impact MRE Digestibility

While MREs are nutritionally engineered to provide balanced calories for high-activity situations, their composition is optimized for shelf-stability, not necessarily fresh food diversity. This design leads to several nutritional factors that can affect digestion.

Low Fiber Content

One of the most significant reasons for the constipation myth is the low dietary fiber content in some MRE components, and the overall diet when MREs are the sole food source. Fiber adds bulk to stool and facilitates bowel movements. When soldiers in the field rely on MREs and omit the often less-desirable fibrous crackers or sides, they may experience a significant drop in their fiber intake, leading to constipation.

High Sodium Levels

MREs are notably high in sodium to help with preservation. High sodium intake, especially when coupled with the high physical exertion and heat often experienced in the field, can lead to dehydration. Dehydration is a primary cause of constipation, as the body pulls water from the digestive system to compensate, resulting in harder stools.

Processed Ingredients and Additives

To achieve their impressive shelf life and palatable taste, MREs contain various processed ingredients, preservatives, emulsifiers, and flavor enhancers. While generally recognized as safe, ingredients like xanthan gum, modified food starch, and MSG can cause bloating, gas, or other digestive issues in individuals with sensitivities. The lack of 'good bacteria' from fresh foods also contributes to a less diverse gut microbiome, which can affect digestive regularity.

The Role of Environmental and Lifestyle Factors

Beyond the food's composition, the context in which MREs are consumed is a critical determinant of digestive outcomes. The military's operating conditions create a perfect storm of digestive challenges.

Stress and Psychological Factors: The constant psychological and physiological stress of field operations can disrupt normal digestive function. The gut-brain axis is a well-documented pathway, and high-stress levels can lead to changes in gut motility and flora.
Dehydration and Insufficient Fluid Intake: In demanding environments, soldiers are often not drinking enough water, exacerbating the high sodium content of the MREs and leading to dehydration-induced constipation.
Disrupted Sleep Patterns: Irregular sleep schedules common in military operations disrupt the body's natural rhythms, which in turn can negatively impact digestive processes and the gut microbiome.
Lack of Physical Rest: Heavy physical activity combined with insufficient rest can also put added strain on the digestive system, contributing to discomfort.

Comparison of Factors Affecting MRE and Balanced Diet Digestion


Feature	MRE-Only Diet	Regular, Balanced Diet
Dietary Fiber	Often low, contributing to constipation if components are skipped.	Higher, derived from varied sources like fruits, vegetables, and grains.
Sodium Content	Very high, designed for high activity and preservation.	Moderate, with greater control over intake.
Processing & Additives	High levels of preservatives and emulsifiers to ensure long shelf life.	Lower levels of additives and more fresh, whole ingredients.
Microbiome Diversity	Limited diversity due to lack of fresh, fermented foods.	Higher, supported by a wide variety of food sources and probiotics.
Environmental Context	Consumed under high stress, dehydration, and irregular sleep.	Consumed in a more controlled, lower-stress environment.

Tips for Maximizing MRE Digestibility

If you find yourself relying on MREs, or simply have a few stashed for emergencies, there are strategies to minimize potential digestive issues:

Hydrate Aggressively: Drink plenty of water throughout the day, especially when consuming high-sodium MRE components. This is the single most important factor.
Don't Skip the Fiber: Always eat the crackers, bread, and other included items that contain fiber. These are critical for maintaining regularity.
Incorporate Fresh Food When Possible: If circumstances allow, supplement your MREs with fresh fruits, vegetables, or yogurt to support your gut microbiome.
Add Fiber Supplements: Carry small, lightweight fiber supplements to mix into beverages if fresh produce is not an option.
Stay Active: Gentle physical activity, like a walk after eating, can aid in digestion and prevent stagnation.
Consider Probiotics: Taking a probiotic supplement can help replenish beneficial gut bacteria and improve overall digestive function.

Conclusion: Context is Everything

The core answer to whether MREs are hard to digest lies not in the food itself but in the circumstances of its consumption. While their specific nutritional profile—low fiber, high sodium, processed ingredients—can present challenges, the more common source of digestive problems is the combination of environmental stress, dehydration, and irregular routines inherent to field conditions. For short-term use, MREs are an effective and safe source of dense nutrition. For extended periods, conscious mitigation strategies like prioritizing hydration, consuming all packet components, and supplementing fiber can significantly improve digestive comfort. Understanding these factors allows for a more informed and healthier approach to consuming military rations, turning the old joke into a manageable reality.

Visit the U.S. Army's official article on their MRE gut health study to learn more.

Frequently Asked Questions

The belief comes from decades of anecdotal evidence from military personnel. While MREs are low in fiber and high in sodium, scientific studies suggest environmental factors like dehydration, stress, and disrupted sleep patterns are the real culprits behind the GI distress experienced in the field.

MREs are generally low in dietary fiber compared to a fresh, balanced diet. It's crucial to eat the included crackers and other fibrous sides to maximize your fiber intake when consuming MREs.

The most important strategy is to stay properly hydrated by drinking plenty of water. Additionally, consume all the fibrous components of the MRE and, if possible, supplement with fresh foods or fiber boosters.

MREs contain preservatives, emulsifiers, and flavor enhancers necessary for long shelf-life. These are generally considered safe, but some individuals may have sensitivities to ingredients like xanthan gum or MSG, which can cause digestive discomfort.

No, this is a myth. The gum contains xylitol, a sugar alcohol that can have a mild laxative effect in large quantities, but a person would need to chew an unrealistic number of pieces to achieve this. The gum's primary purpose is for oral hygiene.

MREs are not intended for long-term, sole consumption. While they are safe and effective for short-term use, relying on them for more than a few weeks can lead to nutritional deficiencies due to the lack of diverse fresh foods.

MREs are designed to provide a high caloric load (approx. 1,200 calories) for active soldiers in demanding environments. The high sodium helps replenish electrolytes lost through sweat, and also acts as a preservative.