Can Milk Reduce Dehydration? The Surprising Science of a Classic Beverage

November 10, 2025 •

4 min read

According to a 2016 study published in the American Journal of Clinical Nutrition, both whole and skim milk were found to be more hydrating than plain water for fluid retention over a four-hour period. This surprising finding reveals that yes, can milk reduce dehydration, and in some cases, it performs even better than a simple glass of H2O.

Quick Summary

Milk's unique nutritional profile, which includes electrolytes, protein, and carbohydrates, helps the body retain fluids for longer periods than plain water by slowing down digestion. This makes it particularly effective for post-exercise recovery and situations requiring sustained rehydration.

Key Points

Superior to Water: Studies show that milk is often more hydrating than water over extended periods due to its unique blend of nutrients.
Electrolytes for Fluid Retention: The natural electrolytes in milk, such as sodium and potassium, help the body hold onto fluid more effectively, reducing urine output.
Slower Absorption: Protein, fat, and lactose in milk slow down gastric emptying, leading to a slower and more sustained absorption of water into the body.
Post-Exercise Recovery: Milk is an ideal post-workout beverage, providing fluid replacement, electrolytes, and the protein needed for muscle repair and recovery.
Considerations: While effective, milk is not for everyone due to its calorie content and potential issues for those with lactose intolerance or milk allergies.
Water as a Staple: For daily, low-calorie hydration, plain water is still the best and most appropriate choice.

The Science Behind Milk's Hydrating Power

While water is universally recognized as the foundation of proper hydration, a series of studies over the last decade have challenged the idea that it is always the most effective option for fluid retention. The key lies in a beverage's nutrient composition and how the body processes it. Unlike plain water, milk is a complex liquid containing a mix of water, electrolytes, macronutrients, and other compounds that collectively aid in hydration.

The Role of Electrolytes and Nutrients

Electrolytes such as sodium and potassium play a crucial role in maintaining the body's fluid balance. When we sweat, these essential minerals are lost along with water. Milk naturally contains these electrolytes, helping to replenish what's lost and ensuring that the body can efficiently absorb and utilize the fluid being consumed.

In addition, the presence of protein, fat, and natural sugars (lactose) in milk significantly affects how it's digested and absorbed. These macronutrients slow down the rate at which fluid leaves the stomach, leading to a more gradual absorption into the bloodstream. This slower, more sustained process helps to prevent a rapid flush of fluids out of the body through urination, resulting in better overall fluid retention compared to drinking plain water.

Milk vs. Other Hydration Sources

To understand milk's effectiveness, it's helpful to compare it with other common rehydration drinks. The following table highlights the differences in their hydration mechanisms and best use-cases.


Feature	Milk (e.g., Low-fat)	Water	Sports Drinks	Oral Rehydration Solutions (ORS)
Primary Function	Sustained hydration, nutrient replenishment, recovery.	General, daily hydration, rapid replenishment.	Rapid rehydration, electrolyte replenishment during intense exercise.	Treats severe dehydration and electrolyte imbalances.
Key Components	Water, electrolytes (Na+, K+), protein, carbs, fat.	Water.	Water, electrolytes, fast-absorbing sugars.	Water, specific ratio of glucose and electrolytes.
Gastric Emptying	Slower due to protein and fat content.	Rapid.	Moderate, influenced by sugar concentration.	Designed for optimal and rapid absorption.
Fluid Retention	High, results in lower urine output over time.	Lower, can lead to quicker fluid loss via urination.	High, formulated for retention during/after exercise.	High, specifically for maximum retention.
Calories	Moderate (e.g., 100-150 kcal per cup).	Zero.	Varies, typically moderate.	Low to moderate.

Using Milk for Post-Exercise Recovery

For athletes or individuals engaging in moderate to intense physical activity, milk is a highly effective recovery beverage. During strenuous exercise, the body loses significant amounts of fluid and electrolytes through sweat. Milk provides a comprehensive solution for replenishment.

Why athletes can benefit from milk:

Electrolyte Replacement: Replenishes the sodium and potassium lost during intense workouts.
Muscle Repair: The high-quality protein in milk provides the necessary amino acids to help repair and rebuild muscle tissue.
Glycogen Replenishment: The carbohydrates, particularly in chocolate milk, help to restore muscle glycogen stores, which are depleted during prolonged or intense exercise.

Research has shown that drinking milk after a workout can be just as, if not more, effective than commercial sports drinks, with the added benefit of high-quality protein for muscle recovery.

Considerations for Using Milk for Hydration

While milk can be a powerful tool for hydration, it isn't the right choice for everyone or for every situation. For general, daily hydration needs, water remains the gold standard, offering fluid without additional calories or nutrients.

Key considerations include:

Lactose Intolerance or Dairy Allergies: Individuals with these conditions should avoid cow's milk and seek alternative hydration sources. Fortified plant-based milks can be considered, but their electrolyte and nutrient profiles differ from cow's milk.
Calorie and Fat Intake: The higher calorie and fat content of whole milk should be considered if you are on a calorie-restricted diet. For a hydrating option with less fat, skim or low-fat milk can be a good compromise.
Severe Dehydration: For severe dehydration, especially accompanied by vomiting or diarrhea, a healthcare professional should be consulted. In such cases, an oral rehydration solution (ORS) is often the most appropriate treatment.

Conclusion: The Final Word on Milk and Dehydration

Can milk reduce dehydration? The answer is a resounding yes, especially when seeking sustained rehydration and nutrient replacement. Milk's unique composition of water, electrolytes, protein, and carbohydrates helps the body retain fluid more effectively than plain water in specific scenarios, particularly after intense exercise. However, water remains the best, zero-calorie option for meeting everyday hydration needs. Integrating milk, especially after a workout, can offer a cost-effective and nutrient-rich approach to optimizing fluid balance and recovery for many individuals.

For those with lactose intolerance, fortified lactose-free milk or certain plant-based alternatives may still offer hydration benefits, but it's essential to check the nutritional information as their electrolyte content can vary.

Frequently Asked Questions

For immediate fluid absorption, water is sufficient. However, for prolonged hydration and better fluid retention over several hours, studies have shown that milk can be more effective than water due to its nutrient composition.

After a workout, the body needs to replenish lost fluids, electrolytes, and glycogen stores. Milk provides all three, along with protein for muscle repair, making it a comprehensive and effective recovery drink.

For general daily hydration, water is the best option because it has no calories. Milk contains calories and nutrients that are better suited for specific situations like post-exercise recovery, rather than replacing water entirely.

Yes, chocolate milk is often considered an excellent post-workout recovery drink. The added sugar provides extra carbohydrates for glycogen replenishment, which is beneficial after intense exercise.

Individuals with lactose intolerance should avoid regular cow's milk. They can consider fortified lactose-free milk or other hydrating fluids. It's best to consult a doctor or registered dietitian for personalized advice.

While plant-based milks like almond or soy are primarily water and can contribute to hydration, they generally lack the same natural balance of electrolytes, protein, and fat found in cow's milk. Some may be fortified, so it's important to check the nutritional label.

For mild dehydration, milk's electrolytes can be beneficial. However, if dealing with severe dehydration or illness involving vomiting or diarrhea, a specialized oral rehydration solution is more appropriate. Always consult a healthcare professional in cases of severe illness.