The extreme heat that has hit most of the world is prompting people to find the best hydration solutions. According to a study from St. Andrews University in Scotland, the drink that has the best hydrating effect is skim milk, CNN reports.
Researchers found that while water – both still and carbonated – does a pretty good job of hydrating the body quickly, drinks with little sugar, fat, or protein do an even better job of keeping us hydrated for longer.

The reason has to do with how our bodies respond to drinks, according to Ronald Maughan, a professor at St. Andrews Medical School and the study’s author. One factor is the volume of a particular drink: The more you drink, the faster the drink empties from your stomach and is absorbed into your bloodstream, where it can dilute body fluids and hydrate you.

The other factor that influences how well a drink hydrates us relates to its nutritional composition. For example, milk has been found to be even more hydrating than plain water because it contains the sugar lactose, protein, and fat, all of which help to slow the emptying of fluid from the stomach and keep you hydrated for longer.

Milk also contains sodium, which acts as a sponge and retains water in the body, resulting in less urine being produced.

The same can be said of oral rehydration solutions that are used to treat diarrhea. They contain small amounts of sugar as well as sodium and potassium, which can also help promote water retention in the body.

Top most hydrating drinks
The team of researchers at St Andrew’s University tested 13 common drinks to see what impact they have on hydration. Here’s what they found, ranked from most hydrating over a four-hour period to least hydrating.

Skim milk

Oral rehydration solutions

Full-fat milk

Orange juice

Coke

Diet cola

Iced tea

Tea

Still water

Sparkling water

Lager

Coffee