Does Milk Actually Hydrate You Better Than Water? The Surprising Truth

October 19, 2025 •

4 min read

According to a 2016 study published in The American Journal of Clinical Nutrition, milk was found to be more hydrating than plain water due to its nutrient composition. This finding prompts many to ask: Does milk actually hydrate you better than water? The answer is more nuanced than a simple yes or no and depends heavily on the context, your activity level, and your overall nutritional goals.

Quick Summary

Milk's electrolytes, protein, and carbohydrates can promote better fluid retention than water, making it superior for rehydration in certain situations like after intense exercise. For general, daily hydration, water remains the best, calorie-free option for most people.

Key Points

Milk's Nutritional Advantage: Milk contains electrolytes, protein, and carbohydrates that help the body retain fluid for longer than plain water, particularly after exercise.
Sustained Hydration: The macronutrients in milk slow down gastric emptying, which leads to a more gradual absorption and sustained hydration effect.
Post-Exercise Recovery: Milk is an excellent recovery drink for athletes as it replenishes fluids and electrolytes while also providing protein for muscle repair.
Water for Daily Use: For everyday, low-intensity hydration, water is the most efficient, calorie-free, and cost-effective option.
Context is Key: Choosing between milk and water depends on your specific needs; milk is better for sustained rehydration after exertion, while water is superior for general maintenance.
Consider Calorie Intake: Unlike water, milk contains calories and sugar, which can be a factor for those managing their weight or with certain health conditions like diabetes.

The Science Behind Milk's Hydration Edge

While water is the undisputed champion for general thirst-quenching, milk's unique composition provides it with an edge for prolonged hydration. The key is in its blend of macronutrients and electrolytes, which plain water lacks. These components work together to help the body retain fluid more effectively and for a longer duration.

The Power of Electrolytes

Milk is a natural source of electrolytes such as sodium and potassium. When we sweat, these crucial minerals are lost, and replenishing them is essential for maintaining fluid balance. Sodium, in particular, plays a critical role in fluid retention by acting like a sponge, helping the body hold onto water rather than passing it quickly as urine. While sports drinks are also formulated with electrolytes, milk's natural balance is a significant advantage over plain water.

The Role of Macronutrients

One of the main reasons milk slows fluid loss is its content of protein, fat, and carbohydrates (lactose). These macronutrients slow the process of gastric emptying, which is how quickly the stomach releases its contents into the small intestine. Because the fluid is absorbed more slowly, the body retains it for longer, leading to better and more sustained hydration over time. This is particularly useful after intense exercise when the body needs more than just simple fluids.

Milk and the Beverage Hydration Index

The concept of the Beverage Hydration Index (BHI) was introduced in a 2016 study that compared the hydrating effects of different drinks. Using still water as the baseline, researchers found that beverages like skim milk, whole milk, and an oral rehydration solution (like Dioralyte) ranked higher in their ability to maintain fluid balance over a four-hour period. This evidence supports the idea that milk's nutritional makeup contributes to its superior fluid retention capabilities in the short term.

When Milk Excels as a Hydrator

There are specific situations where reaching for a glass of milk is more beneficial than water for rehydration. For athletes, milk is often considered a top-tier recovery drink. After a long, intense workout where significant sweat (and electrolyte) loss has occurred, milk offers a triple threat: fluids, electrolytes, and nutrients for muscle repair. The carbohydrates help replenish energy stores, while the high-quality protein aids muscle synthesis. Chocolate milk, with its higher carbohydrate content, is a particularly popular choice among endurance athletes for this reason. Milk can also be a useful tool for managing mild dehydration, especially in specific populations like children or the elderly who may benefit from the additional nutrients.

When Water Remains the Gold Standard

Despite milk's advantages in certain scenarios, water is the best and most appropriate choice for general, daily hydration needs. Here's why:

Zero Calories: Unlike milk, which contains calories from fat, protein, and sugar, water has zero calories. Relying on milk for all your fluid intake would significantly increase your daily calorie consumption, which is not suitable for everyone.
Efficiency: For simple fluid replenishment, water is the most efficient choice. It's absorbed quickly and doesn't require extra processing by the body, making it ideal for maintaining hydration throughout the day without added calories or a full feeling.
Cost and Accessibility: Tap water is free and widely available, whereas milk requires purchasing and refrigeration, making it a more costly and less convenient option for constant hydration.

Milk vs. Water: A Comparative Look


Feature	Milk	Water
Primary Function	Post-exercise rehydration, muscle recovery, and nutritional support.	General, daily hydration.
Fluid Retention	Better for sustained fluid retention due to slower gastric emptying caused by fats, proteins, and carbs.	Passes through the body more quickly.
Electrolyte Content	Contains natural electrolytes like sodium and potassium, aiding in fluid balance.	Lacks significant electrolytes, though some minerals may be present depending on the source.
Calorie Content	Contains calories, with content varying by fat percentage.	Contains zero calories.
Best For	Athletes after intense workouts, or during periods of mild dehydration.	Everyday drinking, casual exercise, and maintaining overall hydration.
Drawbacks	Higher calorie count, fat content, and potential for dairy-related intolerance issues.	May not be as effective for replenishing lost electrolytes after significant sweat loss.

The Verdict on Your Daily Drink

Ultimately, the choice between milk and water for hydration depends on your specific needs. For general fluid intake throughout the day, water is the best and most practical choice. Its zero-calorie nature and rapid absorption are ideal for maintaining hydration without affecting your overall nutritional intake. However, for those recovering from an intensive workout or experiencing mild dehydration, milk's rich profile of electrolytes, protein, and carbohydrates makes it a powerful and effective tool for more sustained fluid retention and recovery. Those with lactose intolerance or milk allergies should, of course, stick to alternative beverages. Knowing the distinct benefits of each can help you strategically use both to support your body's hydration and nutritional needs. For more details on research, consult resources like the American Journal of Clinical Nutrition.

Conclusion

While the headline "milk hydrates better than water" is based on scientific evidence regarding fluid retention, it's a truth that needs context. Milk's combination of electrolytes, proteins, and carbohydrates slows gastric emptying and improves fluid retention, making it an excellent choice for rehydration after strenuous exercise or during mild dehydration. For daily, casual hydration, however, water remains the most efficient, calorie-free, and accessible option for maintaining overall fluid balance. A smart hydration strategy includes knowing when to reach for each beverage to best serve your body's demands.

Frequently Asked Questions

Milk is considered more hydrating in some studies because its natural content of electrolytes (like sodium and potassium), carbohydrates, and protein helps the body retain fluids longer by slowing down gastric emptying, resulting in less immediate urination compared to water.

Yes, after an intense workout involving significant sweat loss, milk can be more effective than water for rehydration. It not only replaces lost fluids and electrolytes but also provides protein and carbohydrates for muscle repair and energy replenishment.

No, you should not replace all your water intake with milk. Water is the best choice for everyday hydration due to its lack of calories. Relying solely on milk would lead to excessive calorie intake, which can be detrimental to weight management.

Some research suggests that skim milk may be slightly more hydrating than whole milk, though both are more effective than water for fluid retention in the short term. The difference may be due to whole milk's higher fat content, but both are beneficial for rehydration.

Plant-based milks are generally not as hydrating as cow's milk because they often lack the same balance of electrolytes, protein, and carbohydrates. While they do contribute to daily fluid intake, they don't offer the same prolonged fluid retention benefits unless fortified to match cow's milk's nutritional profile.

Yes, chocolate milk is often touted as an excellent recovery and rehydration drink, especially after intense exercise. It offers a great balance of carbohydrates and protein, along with fluids and electrolytes, making it a budget-friendly alternative to commercial sports drinks.

Water is the better choice for most people's daily fluid needs, especially those watching their calorie intake, managing diabetes, or who have lactose intolerance or milk allergies. Water is also the most efficient option for rapid rehydration during a workout.