Could a warm cup of tea really be the key to cooling down in hot weather? Or is that just something caffeine fiends tell themselves when they’re still working through a pot of coffee as the temperature hits 30C?
Prof John Tregoning, the author of Live Forever? A Curious Scientist’s Guide to Wellness, Ageing and Death, says it depends on the circumstances. He points to the work of Australian scientist Prof Ollie Jay, who is a world leader in researching heat and how it balances out in your body.
When it comes to drinking a hot beverage, there are two effects on your body. “You’ve got the heat that the drink gives you, and then the amount that you sweat as a result of it,” Tregoning says.
While you’re consuming the warm drink, its high temperature will cause your body temperature to rise. That elevated temperature will trigger you to sweat more.
This is where things become complicated. Sweat cools down the body when it evaporates. When water on the skin turns to gas, it takes heat energy away from the body.
Only some environments are conducive to this process, however. In breezy spaces, the sweat evaporates efficiently, but in places with high humidity or poor ventilation sweat will run off the body instead. “That’s inefficient,” says Tregoning. “When you drink a hot drink in that environment, you get hotter rather than cooler.”
Essentially: drinking a hot drink to cool down after a windy coastal walk? Good. Drinking a hot drink to cool down in a tropical rainforest? Bad.
Tregoning says: “I think the key is to take on fluids, whatever their temperature, especially in hot weather. There isn’t a massive advantage in hot or cold drinks. It’s down to personal preference.”
