Our bodies are made up of 55 to 60 percent water, so it makes sense that we think we need to drink plenty of water to stay hydrated (via Livestrong). Although that's not a bad assumption, there is actually something you should be drinking that will hydrate you faster and keep you hydrated longer than water does.
When it comes to hydration, the natural sugars in milk, combined with its protein and fat content, help the body retain water. Milk also allows for fluids to leave the body at a slower pace. This keeps you from making frequent trips to the bathroom, which means you're hydrating your body for a longer period of time. Milk also contains sodium, and as you may know, salt helps your body retains water. While Teen Vogue explains that too much sodium may cause bloating, when it comes to hydration, a little extra sodium can actually be a good thing. CNN notes that when drinking milk, the sodium content works as a chemical sponge and helps hold water in.
Why milk is more hydrating than water?
This sponge-like effect on your body is why milk ranks so high on the hydration index. The American Council of Science shows that between whole and skim milk, skin milk is more hydrating, falling short only to oral rehydration solutions such as Pedialyte. Sodium is just one of four electrolytes that can be found in milk. According to Livestrong, potassium, calcium, and magnesium are the other three. Registered dietitian and spokeswoman for the Academy of Nutrition and Dietetics, Melissa Majumdar, told CNN, "Electrolytes — like sodium and potassium — contribute to better hydration."
What other drinks impact your hydration?
Sugar, on the other hand, you should be careful of, Majumdar says. The reason milk is the hydrating drink of choice is because of its low sugar content. It contains just enough to get the job done, but not too much where it actually has the opposite effect. Drinks such as sodas and fruit juices, though, contain a high concentration of sugars that will pull water from the body instead of storing it.
Though you want to stay away from sodas and other sugary drinks, and you can never go wrong with water, when you're already dehydrated and need a quick fix, grab a glass of milk. Not only does it do a body good, but it will kick your dehydration faster and last longer than water will.