Is Milk Good for You if You Are Dehydrated?

January 9, 2026 •

3 min read

According to a study published in The American Journal of Clinical Nutrition, milk has been shown to be more effective at rehydrating the body than plain water under certain conditions. This surprising fact challenges the traditional notion that only water can fully address dehydration.

Quick Summary

Milk is a surprisingly effective rehydration option for mild dehydration and post-exercise recovery, surpassing plain water in some studies due to its nutrient composition. Its blend of electrolytes, protein, and carbohydrates helps the body retain fluid more efficiently, though water remains the low-calorie standard for daily needs.

Key Points

Superior Hydration: Studies show milk hydrates more effectively than water after exercise due to its unique blend of nutrients.
Electrolytes are Key: The sodium and potassium in milk help the body retain fluid more efficiently than plain water.
Sustained Fluid Absorption: The presence of protein, carbohydrates, and fat slows gastric emptying, leading to longer-lasting hydration.
Ideal for Recovery: Milk is an excellent post-exercise drink, providing protein for muscle repair and carbs to replenish energy stores.
Consider Your Needs: While effective, milk is higher in calories and may not be suitable for those with lactose intolerance or severe dehydration.
Water vs. Milk: Water is best for daily, low-calorie hydration, whereas milk is superior for post-activity recovery and replacing lost nutrients.

The Scientific Reason Why Milk Aids Rehydration

At first glance, it may seem counterintuitive to reach for a glass of milk when you're parched. However, scientific evidence, including findings from a study at Scotland's St. Andrews University, reveals that milk's unique composition can make it more hydrating than plain water. The key lies in its natural blend of essential nutrients that work together to promote better fluid retention within the body.

The Electrolyte Advantage

Milk contains naturally occurring electrolytes such as sodium and potassium. These charged minerals play a crucial role in maintaining fluid balance inside and outside the body's cells. While water is excellent for restoring fluid volume, it lacks the electrolyte content needed to truly replace what is lost through sweat, especially during intense physical activity. Sodium, in particular, acts like a sponge, helping the body hold onto water and reducing the amount of urine produced.

Macronutrients and Slower Absorption

The presence of carbohydrates (lactose), protein, and fat in milk sets it apart from water. These macronutrients slow down the rate at which fluid leaves the stomach and is processed by the body. This slower gastric emptying allows for a more gradual and sustained absorption of fluids and electrolytes, keeping you hydrated for a longer period. In contrast, plain water is absorbed quickly, which can lead to rapid urination and a feeling of dehydration returning sooner.

Post-Exercise Recovery

For athletes and fitness enthusiasts, milk's benefits extend beyond simple hydration. Its combination of protein, carbohydrates, and electrolytes makes it an ideal post-workout recovery drink. The protein helps repair and rebuild muscle tissue, while the carbohydrates replenish glycogen stores that are depleted during exercise. Studies have shown that both plain and chocolate milk are effective at restoring fluid balance and promoting muscle recovery after strenuous activity, often outperforming traditional sports drinks.

Comparison: Milk vs. Water for Hydration

When choosing between milk and water for rehydration, the right choice depends on your specific situation. This table compares the two to help you decide.


Feature	Milk	Water
Primary Hydration Mechanism	Water content + electrolytes, protein, and carbs for fluid retention.	Pure fluid replenishment.
Best For	Replenishing fluids and nutrients after moderate to intense exercise, or for mild dehydration.	General, everyday hydration and low-calorie fluid needs.
Nutrient Replenishment	Replenishes lost electrolytes, protein, and carbohydrates.	Does not replace electrolytes or provide energy.
Calories	Higher calorie count due to protein, fat, and carbs.	Zero calories, making it ideal for weight management.
Absorption	Slower, sustained absorption due to nutrients.	Rapid absorption and quicker urination.

Considerations and Limitations

While milk has clear benefits, it is not a perfect rehydration solution for everyone or every scenario. For mild dehydration, it is a great choice, but for more severe cases, medical attention is necessary. Furthermore, individuals with certain health conditions or dietary restrictions should approach with caution.

Potential Drawbacks of Milk for Dehydration

Calorie Content: For those watching their weight, the calorie count in milk, particularly whole milk, can be a drawback compared to water. Skim milk offers a lower-calorie alternative while still providing hydrating benefits.
Lactose Intolerance and Allergies: Individuals with lactose intolerance or dairy allergies will experience adverse digestive effects, such as bloating and diarrhea, which can exacerbate dehydration.
Digestive Discomfort: During illness or with moderate to severe dehydration, the body may have difficulty digesting the proteins and fats in milk, which could worsen gastrointestinal symptoms.

What About Plant-Based Milks?

Plant-based milks like almond, soy, or oat milk are primarily water but lack the same electrolyte and macronutrient profile as dairy milk. While they contribute to overall fluid intake, they may not offer the same enhanced fluid retention benefits unless they are specifically fortified. For optimal hydration, fortified options are a better choice if you are avoiding dairy.

Conclusion: The Right Time for Milk

Milk can be an excellent and, in some contexts, superior choice for rehydration, particularly after exercise or for mild cases of dehydration, due to its electrolyte, carbohydrate, and protein content. However, it is not a replacement for water as your primary, daily source of fluid, especially for those managing calorie intake or with digestive sensitivities. For general hydration, plain water remains the gold standard. For intensive recovery, milk offers a powerful nutrient-rich option. When in doubt about severe dehydration, consult a healthcare professional immediately.

For further information on hydration and nutrition, you can review expert guidance from reputable health organizations.

Frequently Asked Questions

For mild dehydration or after exercise, yes. Research indicates that milk's combination of electrolytes, carbohydrates, and protein helps the body retain fluid for longer periods than plain water.

Milk is more hydrating because its nutrient-rich composition, including natural electrolytes and macronutrients, slows down fluid absorption. This leads to less fluid loss through urination and more sustained hydration.

Milk is beneficial for mild dehydration and post-exercise recovery. For severe dehydration, medical attention is required, and simple oral rehydration solutions are generally more appropriate for rapid absorption.

No, if you are lactose intolerant, you should avoid dairy milk for hydration. The lactose can cause digestive issues, which would worsen rather than help your hydration status.

Both are effective, but skim milk might be slightly more hydrating and is lower in calories. Some studies suggest the higher fat content in whole milk doesn't add significant hydration benefit.

Chocolate milk is an excellent post-exercise rehydration drink. The added sugar provides extra carbohydrates to replenish energy stores, making it highly effective for recovery after intense activity.

You should choose water for general, everyday hydration, especially if you are concerned about calorie intake. Water is also the best option for those with milk allergies or lactose intolerance.

Plant-based milks are mostly water and contribute to fluid intake. However, they generally lack the specific electrolyte and macronutrient profile that makes dairy milk so effective for sustained hydration unless they are fortified.