Can Milk Help Hydrate You? The Surprising Truth

December 11, 2025 •

6 min read

According to research from Scotland's St. Andrews University, milk was found to be more hydrating than plain water due to its nutritional composition. This study challenges the conventional belief that water is always the optimal choice for rehydration, prompting the question: can milk help hydrate you more effectively than other beverages?

Quick Summary

This article explores why milk is surprisingly effective for hydration, analyzing the roles of its electrolytes, protein, and carbohydrates. It compares milk to water and sports drinks, highlights the benefits for post-exercise recovery, and discusses key considerations for its use. The piece delves into scientific studies and expert opinions on milk's unique hydrating properties.

Key Points

Milk Hydrates Effectively: Studies show that milk, both skim and whole, is more hydrating than water due to its nutrient content.
Nutrient Composition is Key: The electrolytes (sodium, potassium), protein, and carbohydrates in milk help the body absorb and retain fluids longer.
Ideal for Post-Exercise Recovery: Milk is an excellent post-workout drink, replenishing lost fluids, electrolytes, and muscle-repairing protein.
Slower Gastric Emptying: The fats and protein in milk slow its digestion, leading to less urine output and more sustained fluid retention.
Water is Best for Daily Intake: For general, everyday hydration, calorie-free water remains the most practical and healthiest choice.
Consider Calorie and Lactose Factors: Individuals concerned about calories or with lactose intolerance should be mindful of their milk intake.
Plant-Based Alternatives Vary: Fortified plant-based milks can be hydrating but often lack the full nutrient profile of cow's milk, so check labels carefully.

The Science Behind Milk's Hydrating Properties

While water is crucial for hydration, beverages with additional nutrients can enhance fluid absorption and retention. Milk's composition provides this advantage.

Why Milk Retains Fluid Better than Water

Milk contains a high percentage of water (around 87-90%), but its superior hydration comes from dissolved nutrients.

Electrolytes: Rich in sodium, potassium, and calcium, milk's electrolytes, especially sodium, help the body retain water, reducing immediate excretion through urination.
Macronutrients: Protein, fats, and carbohydrates (lactose) slow gastric emptying, allowing for a more gradual and sustained fluid absorption. This slower rate leads to less urine output and better fluid retention compared to plain water.
Osmolality: Milk's concentration of dissolved particles is similar to body fluids, aiding water absorption by cells.

Milk in Post-Workout Recovery: A Superior Option

Milk is often recommended for post-exercise recovery as a cost-effective, nutrient-rich drink. After intense activity, the body needs to replenish fluids, electrolytes, and energy stores while repairing muscles. Milk's profile makes it suitable for this.

Milk's Recovery Advantage

Rapid and Sustained Hydration: Milk retains fluid longer after exercise, aiding rehydration after sweating. Studies show positive fluid balance is maintained longer with milk.
Muscle Repair: High-quality protein in milk provides amino acids for muscle repair and rebuilding, reducing soreness and aiding recovery.
Energy Replenishment: Lactose helps refuel muscle glycogen. Flavored milk offers more carbs, useful after prolonged activity.

Comparing Milk, Water, and Sports Drinks for Hydration

The Beverage Hydration Index (BHI) ranks drinks based on hydrating potential. Milk scores highly, often above plain water.


Feature	Milk (Full-Fat)	Water	Sports Drink	Notes
Primary Function	Rehydration, recovery, nutrition	Basic hydration	Electrolyte and carb replenishment
Key Hydrating Factors	Water, electrolytes, carbs, protein, fat	Water only	Water, electrolytes, carbs (often added)
Electrolyte Source	Natural	Minimal (depends on source)	Added (often artificial)
Absorption Rate	Slower (due to macronutrients)	Faster (quickly absorbed)	Varies (depends on carb concentration)	Slower absorption leads to less urine output
Calorie Content	Higher	Zero	Varies (often high in sugar)	Higher calories from fats and carbs
Best Used For	Post-exercise recovery, general nutrition	Everyday hydration, general thirst	Intense, long-duration exercise

Important Considerations and Potential Drawbacks

Milk isn't ideal for everyone or every situation. Consider these factors:

Lactose Intolerance: Can cause digestive issues, counteracting hydration. Lactose-free options may vary in hydrating properties.
Caloric Intake: Milk contains calories and macronutrients, which can be a factor for weight management.
Plant-Based Alternatives: Generally have less complete nutrient profiles and fewer natural electrolytes than cow's milk, often with added sugars.

Conclusion: When to Choose Milk for Optimal Hydration

Water is the standard for daily hydration and general thirst. However, milk can hydrate more effectively in specific circumstances, especially post-intense exercise when fluids, electrolytes, and nutrients are lost. Its combination of water, electrolytes, protein, and carbs provides sustained rehydration and muscle recovery. For those without lactose intolerance or high caloric concerns, post-workout milk is a scientifically-backed strategy.

Takeaways for Better Hydration

Assess the Scenario: Choose milk after intense exercise for enhanced rehydration and recovery.
Stick with Water for Daily Needs: Plain water is best for general, everyday hydration due to its lack of calories and simplicity.
Mind the Calories: Be aware that milk contains calories and may not be suitable as a primary fluid source for those on a strict diet.
Consider Lactose Intolerance: Individuals with lactose intolerance should avoid regular milk and explore fortified alternatives or oral rehydration solutions.
Check Plant-Based Options: If choosing a plant-based milk, read the label for fortified electrolytes to gauge its hydrating potential.

What the Experts Say

Clinical dietitian Patricia Kolesa notes milk's electrolyte content makes it hydrating. Registered dietitian Melanie Betz adds that while milk hydrates, water is best for daily needs. Experts agree milk is a powerful rehydration tool, especially for recovery, used strategically with regular water.

Summary of Hydration Strategies

The best hydration choice depends on your needs. Water is unmatched for daily hydration. Milk offers a compelling advantage for sustained rehydration and recovery after a workout. Understanding the science helps inform your decision to optimize fluid balance and performance.

A Balanced Approach to Hydration

A balanced approach is key. Use water for daily needs and milk when more robust replenishment is required, such as after significant fluid loss from exercise or illness. It's a versatile beverage that, used correctly, can be valuable to a healthy hydration strategy.

Beyond the Glass

Hydration also comes from food, like fruits and vegetables. However, for beverages, the choice between milk and water depends on context. Milk's complex composition makes it a slower, more complete hydrator, ideal for total body replenishment rather than just thirst-quenching. The choice isn't about which is inherently better, but which fits the situation. Water daily, milk for recovery.

The Final Word

Research indicates that yes, milk can help hydrate you, often better than water in many scenarios. Its nutrients promote longer-lasting fluid retention. It's not a universal water replacement, but understanding the science allows effective use. A thoughtful approach, using both water and milk as needed, is the smartest strategy.

When is Milk Your Best Hydration Tool?

After a Strenuous Workout: Replacing lost electrolytes, fluids, and muscle-repairing protein is crucial.
During Periods of Mild Dehydration: The sustained fluid retention helps the body recover more steadily.
For Growing Children and Elderly Individuals: Provides both hydration and essential nutrients for bone health.
As a Recovery Meal: When combined with other food sources, it aids in overall replenishment.

The Future of Hydration Science

Research into the BHI and beverage components continues. This will refine understanding of optimal hydration strategies. While milk is strong for specific situations, a holistic approach with various fluids and water-rich foods is recommended.

Additional Considerations

Flavor and Variety: Flavored milk adds carbs for energy, popular with athletes, but check added sugar.
Cost-Effectiveness: Milk is often more budget-friendly than commercial sports drinks, offering a complete nutritional package.
Body Type and Needs: Skim milk offers hydration benefits with fewer calories than whole milk.
Individual Tolerance: If milk causes discomfort, explore other options or consult a professional.

Final Thoughts on Hydration

The idea that milk could be more hydrating than water, while seemingly counterintuitive, is supported by science for specific uses. Hydration is complex, influenced by a beverage's full composition. Understanding this helps make strategic choices. Water is generally sufficient, but milk can be a powerful rehydration and recovery tool.

Post-Workout Rehydration with Milk

For athletes, milk's benefits for post-workout recovery are compelling. Fluids, electrolytes, and protein aid rehydration and muscle repair. This makes milk a powerful tool for optimizing recovery and performance, distinct from simple water. Slower gastric emptying provides sustained release of fluids and nutrients.

Milk vs. Water for Everyday Hydration

Water is the best choice for general daily hydration; it's calorie-free and accessible. Milk's added calories and nutrients are beneficial in specific situations, not for simple hydration. Match the beverage to needs: water for baseline hydration, milk for targeted rehydration and recovery.

The Takeaway

The question "can milk help hydrate you?" has a nuanced answer: yes, and in specific contexts, better than water. Its nutrients lead to longer fluid retention. It's not a universal water replacement, but understanding the science allows effective use. A thoughtful approach, incorporating both water and milk as needed, is the smartest strategy.

Additional Research

Further studies on milk's hydration mechanisms, specific components, and comparison with fortified alternatives could offer more detail. Research on the BHI is valuable for comparing drinks and refining hydration strategies.

Expert Consensus on Milk's Role

Experts generally agree milk is an effective rehydration tool, especially post-exercise. Dietitians highlight its nutrient profile. While water is for daily needs, strategic milk use for post-workout recovery is supported. This balanced perspective helps consumers make informed choices.

Future Hydration Options

Progress in food science may bring new hydration options, like fortified plant-based milks. However, cow's milk remains a natural, available, and scientifically-backed option for enhanced rehydration and recovery. Its history as nutritious is now supported by a deeper understanding of its hydrating properties.

Frequently Asked Questions

Yes, in certain situations, milk is more hydrating than water. Studies using the Beverage Hydration Index have shown that milk is better at keeping the body hydrated for a longer period, primarily due to its nutrient composition of electrolytes, protein, and carbohydrates.

Milk helps you retain fluid longer because its protein, fats, and lactose slow down the process of gastric emptying. This allows the body to absorb the fluid and electrolytes over a more extended period, reducing the immediate fluid loss through urination that often occurs with plain water.

Both skim and whole milk are highly effective for hydration. Skim milk offers the same hydrating benefits from its electrolytes and protein with fewer calories, making it a better option for those managing their weight. The higher fat content in whole milk can slow absorption further but is not proven to offer additional hydration benefits.

Milk is an excellent post-workout drink because it not only rehydrates but also provides high-quality protein for muscle repair and carbohydrates to replenish energy stores. Chocolate milk is a particularly popular recovery drink due to its ideal carb-to-protein ratio.

Plant-based milks are mostly water and can contribute to hydration. However, their electrolyte and nutrient content is typically lower than cow's milk unless fortified. Always check the nutrition label to understand the hydrating potential and be mindful of added sugars.

No, you should not replace water with milk for daily hydration. Water is calorie-free and essential for general fluid needs. Milk, with its calories and macronutrients, is best used strategically for specific purposes like rehydration after intense exercise.

No, regular cow's milk is not suitable for individuals with lactose intolerance. For these individuals, consuming regular milk can cause gastrointestinal distress that undermines hydration efforts. Lactose-free milk or other alternatives should be considered.

Milk's ability to promote fluid retention is a positive for rehydration, not a negative. The slower absorption and reduced urination ensure fluids are utilized by the body instead of quickly expelled. This is different from water retention caused by excess salt or medical conditions.