What drink is more hydrating than water?: A deeper look at fluid retention

October 5, 2025 •

4 min read

According to a study from Scotland's St. Andrews University, beverages containing a little bit of sugar, fat, or protein can keep you hydrated longer than plain water. This insight challenges the common belief that water is always the most effective option, making the question of what drink is more hydrating than water? more complex than it seems.

Quick Summary

This article explores how certain beverages like milk and oral rehydration solutions can be more hydrating than water due to their unique composition of electrolytes and macronutrients, aiding in better fluid retention for longer periods.

Key Points

Nutrient Composition Matters: The presence of electrolytes, protein, and moderate carbohydrates in a beverage can make it more hydrating than water by slowing digestion and increasing fluid retention.
Milk for Sustained Hydration: Milk, both skim and full-fat, has a higher hydration index than water due to its protein, lactose, and electrolytes, making it excellent for post-exercise recovery.
ORS for Targeted Rehydration: Oral Rehydration Solutions (ORS) are medically formulated with a precise balance of salts and glucose to treat dehydration caused by illness more effectively than plain water.
Water is Best for Everyday: For general daily consumption and low-intensity activity, water is the most appropriate and healthiest hydration choice, as it's calorie-free and lacks unnecessary additives.
Context is Key: Choosing the most hydrating drink depends on the situation; intense exercise, illness, or prolonged heat exposure warrant different beverage choices than average daily routines.

The Science of Hydration Beyond Plain Water

While water is the universal standard for hydration and is essential for most bodily functions, the body's fluid retention is influenced by more than just water content. The secret to 'superior' hydration lies in a drink's nutritional composition, which affects how quickly the stomach empties and how efficiently the intestines absorb and hold onto fluid. The key players are electrolytes, carbohydrates, protein, and fat.

The Role of Electrolytes and Nutrients

Electrolytes: Minerals like sodium and potassium act like sponges, helping the body retain water. This is why oral rehydration solutions (ORS) are so effective; they are specifically formulated with a precise balance of electrolytes to optimize fluid absorption.
Carbohydrates (Sugar): In moderate amounts, carbohydrates aid in the absorption of fluids in the small intestine. This is because glucose co-transports with sodium, and for each cycle of this transport, hundreds of water molecules are absorbed to maintain osmotic equilibrium. However, too much sugar can have the opposite effect, causing the body to pull water into the intestine to dilute the sugars, which is why sodas are less hydrating.
Protein and Fat: The protein and fat found in beverages like milk can slow down gastric emptying. This slower digestion means fluids are released and absorbed over a longer period, resulting in less urine production and better, more sustained hydration compared to plain water, which empties quickly from the stomach.

Leading Hydration Champions and Their Benefits

Milk: The Unexpected Winner

Research has consistently shown that milk is one of the most hydrating beverages, often outperforming plain water, especially in rehydrating after exercise. Its success is attributed to its balanced mix of water, natural sugars (lactose), high-quality protein, and electrolytes. The combination of protein and fat slows digestion, while sodium helps the body retain the fluid, making milk an excellent choice for sustained hydration and muscle recovery.

Oral Rehydration Solutions (ORS)

Developed for treating severe dehydration from illness, ORS are a scientifically formulated blend of water, glucose, sodium, and potassium. Their precise composition enables rapid and efficient fluid absorption in the intestines, making them far more effective than water alone for recovery from excessive fluid loss due to diarrhea or vomiting.

Other Highly Hydrating Beverages

Broth: High in sodium and water, chicken or vegetable broth is an excellent source of electrolytes, particularly useful when recovering from illness.
100% Fruit Juice: Juices contain water and potassium, but their high sugar content can be a drawback. They should be consumed in moderation or diluted.
Coconut Water: Known for its potassium content, coconut water is hydrating but often lacks sufficient sodium for heavy sweaters.
Herbal Teas: Caffeine-free teas are essentially flavored water and are just as hydrating as plain water, providing a pleasant variety without added sugars.

A Comparison of Popular Drinks and Hydration


Beverage	Key Hydration Factor	Key Composition	Best For	Caveat
Plain Water	Quick absorption	100% water	Everyday hydration, low-intensity activity	Lacks electrolytes for optimal retention
Skim Milk	High electrolytes, protein, slow gastric emptying	Water, protein, lactose, sodium, potassium	Post-exercise recovery, sustained hydration	Contains calories and natural sugars
Oral Rehydration Solution	Balanced glucose and salts for optimal absorption	Water, glucose, sodium, potassium	Treating mild-to-moderate dehydration from illness	Designed for medical use, not daily drinking
Sports Drink	Electrolytes and carbs for rapid replenishment	Water, sodium, potassium, sugars	Intense exercise (>1 hr) or heavy sweating	Often high in added sugar and calories
Coconut Water	High potassium, natural source	Water, potassium	Replenishing potassium, light hydration	Low in sodium, can be high in sugar
Broth	High sodium and water	Water, sodium, protein	Illness recovery, replenishing salt loss	Sodium content might be high for daily use

When Water is Still the Best Choice

While other drinks can offer superior hydration in specific circumstances, plain water remains the best, most versatile, and healthiest choice for daily fluid intake. It provides hydration without extra calories, sugar, or additives, making it ideal for maintaining proper bodily functions throughout the day. For average, non-strenuous activity, water is perfectly sufficient.

Conclusion: Choosing the Right Hydration

In the grand scheme of Nutrition Diet, water is the cornerstone of a healthy fluid intake. However, the notion of what drink is more hydrating than water? is a valid one in specific contexts, particularly after intense exercise, during illness, or for prolonged periods. In these situations, beverages with a careful balance of electrolytes, protein, and carbohydrates, like milk or ORS, can provide more effective and sustained rehydration. Ultimately, a nuanced approach to hydration, incorporating a variety of fluid sources while prioritizing plain water for daily needs, is the best strategy for optimal health. For more detailed information on a balanced diet and hydration strategies, consult the CDC guidelines on healthier drinks.

Frequently Asked Questions

Studies have shown that milk can be more hydrating than water in certain situations, especially after exercise. This is because its electrolytes, protein, and fat slow down fluid release from the stomach, allowing for longer-lasting hydration.

You should use an Oral Rehydration Solution (ORS) when experiencing significant fluid loss from illness, such as vomiting or diarrhea. Its balanced blend of glucose and electrolytes is specifically designed for rapid and efficient rehydration in these medical situations.

For most people engaging in short or low-intensity workouts, water is sufficient. However, for intense exercise lasting over an hour or in hot conditions, sports drinks with electrolytes and carbs can help replenish what is lost through heavy sweating more effectively than water.

Coconut water is a good source of potassium and can be hydrating, but it often lacks the high levels of sodium necessary for athletes who lose a significant amount of salt through sweat during intense activity. It is not a direct replacement for sports drinks in heavy exercise.

Beverages with high sugar concentrations, like soda, can pull water from the body into the small intestine to dilute the sugar during a process called osmosis. This can actually hinder hydration rather than aid it.

In moderation, regular coffee and tea are generally as hydrating as water. A high intake of caffeine, however, can have a mild diuretic effect, causing you to lose excess fluid. Adding a little milk can help offset this effect.

The Beverage Hydration Index (BHI) is a measure that compares how well different drinks maintain hydration relative to plain water. Studies have used it to show that drinks like milk and ORS have a higher BHI than water.