The Surprising Drink That Hydrates Better Than Water

When it comes to quenching thirst, water is the go-to choice for most of us. It’s refreshing, calorie-free, and essential for our survival. But here’s a twist—research suggests that plain water might not actually be the most effective drink for keeping you hydrated over time.

A study by researchers at the University of St. Andrews in Scotland found that certain drinks outperform water in terms of hydration, thanks to the way our bodies absorb and retain fluids.

Why Some Drinks Keep You Hydrated Longer

Hydration isn’t just about how much liquid you drink — it’s about how long your body holds onto that fluid. Two key factors play a role:

1. Volume of the drink—Larger amounts of fluid leave the stomach faster and are absorbed more quickly into the bloodstream.

2. Nutrient composition—Drinks containing small amounts of sugar, protein, or fat slow down how quickly fluid leaves the stomach. This means hydration is released into the body more gradually, helping it last longer.

Milk: The Unexpected Champion

One beverage topped the hydration chart—skim milk. Surprised? Milk contains a natural mix of lactose (sugar), protein, and fat, along with electrolytes like sodium and potassium. These components help the body retain water and reduce fluid loss through urine.

Oral rehydration solutions, like those used to treat dehydration from illness, came in second place. These solutions combine water with small amounts of sugar and electrolytes, making them highly effective for fluid replacement.

Ranking the Most Hydrating Drinks

Here’s how the study’s four-hour hydration test ranked common drinks, from most to least hydrating:

1. Skim milk

2. Oral rehydration solution

3. Whole milk

4. Orange juice

5. Cola

6. Diet cola

7. Iced tea

8. Hot tea

9. Sports drinks

10. Still water

11. Sparkling water

12. Lager beer

13. Coffee

The Sugar Factor

While some drinks with sugar can help hydration, too much sugar can work against you. Highly sweetened beverages like soda or fruit juice can pull water into the intestines during digestion, temporarily taking it away from the rest of your body. That’s why they’re not as effective as lower-sugar drinks for hydration.

What About Alcohol and Caffeine?

Alcohol is a diuretic, meaning it increases urine production. The effect depends on the strength of the drink—beer has a lower alcohol concentration and contains more water, so it’s less dehydrating than hard liquor.

Coffee’s hydration effect depends on caffeine content. A standard cup with around 80 mg of caffeine hydrates similarly to water. However, consuming high amounts of caffeine (300 mg or more) may have a mild diuretic effect, especially for those not used to it.

The Bottom Line

For everyday hydration, water is still a great choice—it’s cheap, accessible, and calorie-free. But if you want longer-lasting hydration, especially after exercise or during hot weather, drinks like skim milk or an electrolyte solution may be even more effective.

The key is balance: choose beverages that provide both fluid and essential electrolytes, but avoid excessive sugar or alcohol that can undo your hydration efforts.