When you are thirsty, of course you can always reach for a glass of water, but as stated in a survey of Scottish Unit St. Andrews, though, water is not the drink that will keep you best hydrated.

Researchers have found that while water does a pretty good job when it comes to hydration, drinks with a little sugar, fat and protein do an even better job as they keep us hydrated for longer.

"The reason why these drinks keep us hydrated for longer is related to the way our bodies respond to drinks," said Ronald Mugan, a professor at St. George's School of Medicine. Andrews and author of the study.

One factor is the amount of drink consumed: the more you drink, the faster your drink is emptied from your stomach and absorbed into your bloodstream, where it can dilute your body fluid and keep you hydrated.

Another factor that affects how well a beverage hydrates relates to the nutrient composition of the drink.

For example, milk has been found to be more hydrating than plain water because it contains lactose, some protein and some fat, all of which help slow the gastric fluid discharge and keep you hydrated for an extended period, Klix.ba reports.

Milk also contains sodium which acts like a sponge and is retained in the body, resulting in less urine being generated.

"This research tells us a lot of what we already knew. Electrolytes - such as sodium and potassium - contribute to better hydration, while calories in drinks lead to slower gastric emptying and thus slower urination, ”said dietitian Melissa Majumdar.

Moderate with sugars

Beverages with a higher amount of sugar, such as fruit juices, are not necessarily as hydrating as juices with a lower sugar content. They will linger for a little longer in the stomach and discharge more slowly compared to water, but once these drinks enter the small intestine their high sugar concentration is diluted during a physiological process called osmosis. This process actually "draws" water from the body into the small intestine to dilute the sugars contained in these beverages. And technically everything inside your gut is outside your body.