If given the choice, most people would most likely opt for a cold drink on a hot day versus a steamy cup of tea. However in many countries with consistently warm climates, it’s common practice to consume hot drinks. Though it may sound unusual, many claim that it helps to beat the heat. But is there any truth behind this trick?
In the Smithsonian article “A Hot Drink on a Hot Day Can Cool You Down,” researcher Ollie Jay at the University of Ottawa’s School of Human Kinetics, believes that this is possible—provided that the body is able to sweat it out in a dry environment.
“Yes, the hot drink is hotter than your body temperature, so you are adding heat to the body, but the amount that you increase your sweating by—if that can all evaporate—more than compensates for the added heat to the body from the fluid,” Jay states.
As the sweat evaporates, the body cools itself down, meaning that the dryer the climate, the more likely you are to reap the benefits of this effect, he explains.
NPR’s Joe Palca of the radio show Joe’s Big Idea interviewed University of Cambridge neuroscientist Peter McNaughton on the subject. “The hot drink somehow has an effect on your systematic cooling mechanisms, which exceeds its actual effect in terms of heating your body,” McNaughton says.
A receptor called TRPV1 is especially prominent amongst the nerves in the tongue, he explains. When one consumes something hot, TRPV1 receives this signal, and then sends a message to the brain to help cool the body off. The brain obliges with a familiar mechanism—sweating.
The same effect can be observed when one eats spicy foods like peppers or chilis, and certain spices in dishes. In Deutsche Welle’s article “Does Drinking Hot Drinks on a Cool Day Really Cool You Down?,” Dr. Christopher Gordon explains that the flash of heat that you experience after after eating something like curry is courtesy of the central nervous system. Just like a hot drink, the body’s response to the heat is to raise the skin’s temperature, Gordon, an expert in human thermoregulation at the University of Sydney, says.
“This in turn will move the heat away from the body to the skin and then to the air surrounding the body,” Gordon says.
Still, the circumstances must be right in order to benefit from this cooling system. A dry environment best evaporates the sweat that’s created in this process. If the environment has a high humidity level, drinking something hot will increase the discomfort from the heat.