Working or playing outside on a very hot day? There are some cool ways to lower your temperature and prolong the fun without having to resort to an ice bath if you overheat, which is dangerous.

But the best drink, according to experts interviewed by the Washington Post, is a slushy.

Or rather, any method of consuming small pieces of ice, including snow cones. The important thing is that it is actual ice and you don’t choke on it. Hence drinkable ice. Not a drink with ice.

“Swallowing ice takes advantage of a peculiar physics: Melting ice absorbs a lot of heat without actually warming up. In your stomach, much of your body heat is used just to break up the ice crystals – and then when they’re all melted, you’re left with a belly full of cold water that gradually absorbs even more heat from your body,” writes Nicolás Rivero, the Post’s climate solutions reporter.

The recommendation is based on two studies.

In 2020, Australian and British researchers investigated what prolongs the ability to stay outside in very hot temperatures. They found that wearing water-permeable suits in the heat, drinking a slushy before work, and wearing an ice vest increased heat tolerance. The study was published in Applied Ergonomics.

Another study, published in 2014 in the journal Applied Physiology Nutrition and Metabolism, found that both cold water immersion and ingestion of ice-cold slush were very effective in cooling down a group of firefighters participating in a simulated search and rescue operation.

So how much Slurpe do you need? The Post reported that both studies suggested about one ounce of liquid sweetener per eight pounds of body weight. So the firefighters, who each weighed about 185 pounds, got by just fine with “23 ounces, which is about the same as a large Slurpee from 7-Eleven.”

You can drink your iced beverage before you go out, while you’re out in the heat, or after you get back inside. According to the post, it doesn’t matter how fast you drink it either. Just don’t let it melt.

Cool, right?