As temperatures climb, watching your fluid intake becomes an important part of getting through the summer months. Our instincts tell us that hot drinks, like tea and hot cocoa, are meant for the cooler fall and winter weeks, while an ice-cold beverage will do a better job of cooling us down during those sweaty summer days. But is that actually true?
A team of researchers at the University of Ottawa’s School of Human Kinetics set out to find an answer by measuring how much heat cyclists stored in their bodies when given either hot or cold drinks while riding their bikes.
Published in Acta Physiologica, the experiment showed that athletes who consumed hot water could actually lower their body temperature because it triggered a fundamental physiological function that regulates heat: sweating. However, the study also showed that the effect only works under specific environmental conditions.
Success of Hot Beverages Depends on Humidity
The 2012 study describes how cyclists were equipped with skin-temperature sensors and a mouthpiece that recorded oxygen and CO₂ concentrations in their breath. All participants underwent the experiment under the same temperature and humidity conditions while being given beverages of different temperatures.
The results found that participants who consumed water at 122 degrees Fahrenheit stored less heat in their bodies than cyclists drinking cold water. But these results only matter under one specific condition: a hot, dry environment. The additional sweat produced by drinking hot liquids can only evaporate efficiently when humidity levels are low. Therefore, spending time in humid environments might increase sweating without providing the same cooling effect through evaporation.
Read More: From a Healthy Heart to Improved Mood, Here's How Water Gives Your Body a Boost
Consuming Hot Beverages in Heat Is Rooted in Many Cultures
Biology has equipped us with a remarkable mechanism for cooling down. By excreting a thin layer of liquid onto the skin, our bodies can reduce their temperature as that moisture evaporates. Sweating, although sometimes viewed as unhygienic or something to be avoided, relies on basic principles of thermodynamics to keep us from overheating. However, extensive sweating can deplete the body of fluids, making proper hydration essential during warm weather and exercise.
Cultures in warm, arid regions have been consuming hot beverages for thousands of years. Drinking tea is common throughout the Middle East, among the desert nomadic tribes of North Africa, and enjoying a cup of hot chai in India. Whether these traditions developed specifically to regulate body temperature is debatable, as hot beverages were often prepared mostly for sanitation purposes as well, but they certainly did not make the heat any worse.
In the age of refrigeration, it is logical to reach for cool beverages when trying to refresh ourselves during hot weather. Yet access to this technology is a very recent development in human history, and communities thrived in virtually every climate zone on Earth for millennia before it became available.
Meeting Daily Hydration Needs Is Crucial
Does that mean a cold drink does the opposite? Interestingly, when we drink ice-cold beverages, our bodies must expend energy warming the liquid to body temperature, which technically burns calories. But that does not mean it raises our core temperature.
What matters most during warm weather is keeping up with your recommended daily fluid intake. According to the Centers for Disease Control and Prevention (CDC), drinking enough fluids is crucial for preventing heat-related illness, with water being the preferred choice. The agency stresses the importance of staying hydrated throughout the day, especially when working outdoors, while avoiding the consumption of more than 48 ounces of water per hour.
M.D. Bethany Agusala of the Department of Internal Medicine at UT Southwestern Medical Center recommends approximately 92 ounces of water per day for women and 125 ounces for men. While that may sound like a lot, she notes that not all fluids need to come from beverages. Many healthy fruits and vegetables (including cucumbers, tomatoes, and watermelon) have a high water content and can be a tasty way to stay on top of your hydration needs.
This article is not offering medical advice and should be used for informational purposes only.
Read More: People Sweat Differently Than Traditionally Thought, Perspiring in Pools Not Droplets
Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
- This article references information from a study published in Acta Physiologica: Body heat storage during physical activity is lower with hot fluid ingestion under conditions that permit full evaporation
- This article references information from the CDC: Hydration
- This article references information from UT Southwestern Medical Center: 25 water-rich foods to help you stay hydrated this summer
