Hydration is essential for overall health, and there’s been a growing debate over whether milk can outperform water as a hydrating beverage. While some studies hint that milk may have advantages, the evidence remains inconclusive. Let’s explore the research and its implications.
Several small studies have examined milk’s ability to hydrate the body compared to water and sports drinks.
2007 Study
This study involved 11 participants who exercised to significant dehydration levels before rehydrating with milk, water, or a sports drink. Results showed that milk led to less urine output, suggesting better fluid retention.
2016 Small Study
Involving seven men, this study tested fat-free milk, water, and a sports drink after dehydration from exercise. Once again, milk appeared to retain fluids more effectively than water or sports drinks.
2016 Larger Study
Seventy-two healthy men were studied in a controlled environment without intense dehydration. Participants drank fluids like water, milk (skim and whole), orange juice, tea, coffee, beer, and an oral rehydration solution. Milk and the rehydration solution performed best in retaining fluids, while other drinks produced results similar to water.
The findings seem promising for milk. However, several factors complicate the conclusion.
The Limitations of These Studies
- Small Sample Sizes
Studies with a small number of participants, like the 2007 and 2016 small studies, may not provide results that can be generalized to larger populations. - Niche Conditions
Two of these studies involved intense exercise in hot conditions, leading to significant dehydration. These conditions don’t reflect typical daily activities or moderate workouts, making the results less applicable to the average person. - Narrow Definition of Hydration
These studies equated better hydration with reduced urine output shortly after consuming fluids. While fluid retention is one measure of hydration, it’s not the only or necessarily the best one. - Calories and Practicality
Milk’s caloric content makes it less appealing for casual hydration. For example, consuming the amount of milk tested in the small 2016 study would add over 1,000 calories — something most people would want to avoid if not engaging in intense physical activity.
Hydration Trends and Misconceptions
The focus on hydration has grown into a significant cultural phenomenon, often fueled by marketing from companies selling sports drinks, water bottles, and even intravenous hydration services. While staying hydrated is essential, the idea that everyone must constantly sip water or track their intake closely isn’t well-supported by science. For most healthy individuals, drinking when thirsty is a sufficient strategy.
Even trends like “emotional support water bottles,” popularized on social media, suggest an overemphasis on hydration. Unless you’re losing fluids rapidly due to heat, intense exercise, or illness, hydration doesn’t require constant vigilance.
When Is Dehydration a Serious Concern?
For individuals working or exercising in extreme heat, the elderly, children, or those with illnesses causing fluid loss (e.g., diarrhea), dehydration can pose serious risks. In these cases, rehydration is critical, sometimes necessitating intravenous fluids in medical settings. For others, the focus should remain on maintaining a balanced approach — drinking fluids as needed without obsessing over exact intake.
The Verdict
Milk may offer advantages over water in specific, high-intensity scenarios, but for everyday hydration, water remains the simplest, calorie-free, and cost-effective choice. While milk could be part of your post-workout routine or recovery plan, most people don’t need to ditch their water bottles just yet.
