December 12, 2016


Last updated: Feb 24, 2016

When British explorer Henry Worsley died crossing Antarctica last month, the event made front page news.  Less noted was one of the causes of his death: dehydration.  Why would dehydration become such a vital factor in frigid temperatures? Losing excessive amounts of body fluid is not usually a hazard associated with cold weather.  In fact, most people associate dehydration with summer heat and humidity. But winter, too, can drain the body of essential fluids for several reasons:

  • In winter, we tend to go for longer periods without water, not realizing that breathing cold and dry air causes the body to lose significant amounts of fluid.
  • When we perspire in cold weather, the sweat turns into vapor and isn’t directly on our skin, so there is not the excessive perspiration that acts as a visual cue for us to drink.
  • In winter, people feel about 40 percent less thirsty, even though the body’s need for water is unchanged year round.
  • Because we don’t feel thirst as acutely as well do in summer, we’re less likely to keep a bottle of water handy during cold-weather months.

Dehydration is a danger for the body. But most people don’t realize the hazards it poses to the heart.  

“People become dehydrated if they drink less than six eight-ounce glasses of water a day,” says William A. Tansey, III, MD, an expert in cardiovascular disease at Summit Medical Group.  “With less blood volume the heart has to beat faster to keep up.”

Why is it so important to heart health that the body stay adequately hydrated?  Consider these numbers. The body is 70 percent water.  It is essential to health to maintain that level of water to regulate metabolism and stay healthy.  So, for example, if an individual weighs 100 pounds, 70 pounds of that weight should be water.  If this ratio drops, the heart is deprived of fluid, and it has to pump harder to get blood circulating and blood volume decreases. To preserve itself the body directs blood flow to the body core and the organs. As a result, the blood vessels in the extremities, called the “peripheral vessels” stiffen up.

There is a natural loss of fluid during the day from respiration and perspiration.  If you do exercise of any kind, you need to drink a liter of fluid to maintain a healthy proportion of water in the body.  If you wrap yourself in warm clothing, for example if you’re skiing and wrapped layers, you sweat even more and you need to drink more.

According to the website of the Human Performance Resource Center, a Department of Defense initiative: The combination of heavy clothing and high-intensity exercise can lead to increased sweating and the possibility of dehydration. You may not feel as thirsty in cold weather as in other climates, because your body chemistry impairs your brain’s ability to tell you when to hydrate.” (1)

“One group of people who often become dehydrated are fire fighters because they are working strenuously in heavy layers of clothing,” says Dr. Tansey, giving an example of why wrapping yourself in heavy clothing and then exercising can add to the risk of dehydration.”

You can enjoy outdoor activities and stay active in cold weather—hiking, running, skiing or snow shoeing, for example—but be aware of maintaining your body’s ideal ration of water.

To avoid dehydration in cold climates:

  • Take fluids with you before you leave the house. 
  • If you don’t feel like drinking water, drink a warm non-caffeinated drink, such as hot tea to help the body stay hydrated.
  • Drink often, even if you are not thirsty.
  • Remember that certain fluids dehydrate the body.  These include alcohol, carbonated drinks and caffeinated drinks, including sports drinks and energy drinks.
  • Monitor the color and amount of urine your body is producing.  Your urine should be light yellow or clear.  If it is darker, drink more water.
  • Familiarize yourself with other common symptoms of dehydration including fatigue, lightheadedness and even irritability.

“Any responsible person getting exercise in the winter keeps a body of water to stay hydrated. If you can assist the body in homeostasis, you’ve done it a great favor,” Dr. Tansey says.


1) Department of, HPRC Defense. "Dehydration and Cold Weather." Human Performance Resource Center. Human Resources Performance Center, 12 Dec. 2014. Web. 10 Feb. 2016.

2) Tansey, William, MD.  Personal Interview.  7 February 2016

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