Updated: Jun 22
Every hiker’s worst nightmare, besides the dreaded grizzly, is running out of water on the trail. Consequently, hikers tend to carry the bulk of their pack weight in water, especially if water sources are limited. But is all that water really necessary?
Our bodies are made of up to 75% water, depending on our age. Therefore, it’s essential to our existence. However, with that much water on board, the body has a bit of a built-in cushion. After all, a healthy adult human can live about three days without additional water. So the danger of true dehydration from a day hike is unlikely.
Dehydration is excessive water loss. It means that the body has lost so much water that it is unable to perform its necessary functions. Dehydration often occurs as a result of a gastrointestinal illness, which causes excessive vomiting and diarrhea. Older people are especially sensitive to dehydration due to the lower volume of water in their bodies. Some medications can make older persons even more susceptible to dehydration. In addition, aging dulls the sensation of thirst in the elderly; thus, older persons may not consume enough fluid. Infants and young children who can’t communicate are also more susceptible to dehydration.
There are degrees of dehydration, from mild to severe. Most healthy adults will follow the instinct to drink driven by thirst unless they don’t have access to safe drinking water or have a medical condition that affects their sensation of thirst. The adage that if you’re thirsty, you’re already dehydrated may be a function of good marketing by sports drink companies rather than accurate physiology. (For more on this, see Christie Aschwanden’s excellent book on recovery, Good to Go.)
The body is a finely tuned machine that works to maintain homeostasis. That means, despite many variables such as nutrition, hydration, sleep, exercise, etc., it keeps everything running at the same status through a series of feedback loops. If the sodium concentration in the blood is too low, it draws off water and excretes it as urine to keep the right electrolyte balance. If it is too high, it pulls water out of the kidneys back into the bloodstream to dilute the sodium levels. If those water levels fall further, it triggers the thirst mechanism to obtain more fluid. Thirst is the safety valve that prevents significant dehydration.
When trekkers get dehydrated, it’s likely because they’ve ignored their thirst. Reasons that they might miss the signs that they are thirsty include:
· Being in the zone occupied with the technicalities of the trail;
· Not wanting to hold up the group by stopping to drink;
· Deferring drinking until you get to the next stop.
So while hikers can become dehydrated, it’s likely not because they forgot to drink, but because they ignored their bodies’ signal to do so. To combat this, athletes and hikers often try to adhere to a drinking schedule. They set a timer on their watches to remind them to drink every 15 minutes or so. The problem with scheduled hydration is that it ignores the body’s natural signals and cause over-hydration. Over-hydration often presents similarly as dehydration with symptoms such as:
· Listlessness or lack of energy
· Muscle spasms or cramps
Extreme over-hydration lowers the concentration of sodium in the bloodstream and causes hyponatremia. This condition often results in seizures, coma, and death.
What’s the right formula?
How much water you carry and how much water you drink don’t have to be equal. The typical formula for the amount to pack is a half-liter of water for every hour of hiking. When going out on a hike, carry more water than you think you will need. It’s much better to have a little extra weight than to encounter issues on the trail and be without water.
Remember, your hydration isn’t just the number of glasses of water you drink each day. All the items you consume that contain fluid count too. This includes the coffee you drank for breakfast, the ramen and hot tea for lunch, and the water in your dehydrated meal at dinner.
Instead of the glasses per day formula to determine how much you should drink, let thirst be your guide. That means you may have to train yourself to be attentive to your thirst mechanism. One way to maintain sodium and hydration levels is to bring salty snacks on the trail. Pretzels and Pringles are excellent foods that are easily digestible for quick energy and provide plenty of sodium. Salty snacks will also trigger your thirst more readily.
Heat stress and heat stroke aren’t necessarily caused by dehydration, although dehydration can make them worse. In an emergency, NOLS recommends only giving water if the injured person is thirsty. Avoid the instinct to think everyone is dehydrated, especially since it presents with similar symptoms to over-hydration and heatstroke.
To stay safe and hydrated on the trail, here's the basics:
Pack at least one-half of a liter per hour of hiking.
Pay attention to your thirst and drink if you’re thirsty.
Use a backpack/bladder system to make drinking easier and keep you from having to stop to take a sip.
Avoid substances that cause dehydration, like alcohol and caffeine.
Eat salty snacks to help trigger your thirst.
Remind the very young and the elderly to drink more frequently as their thirst mechanism may not be as sensitive.
Invest in a water filtration system to use when water is available on the trail.
Trust your body to tell you when it’s time to drink up rather than using a time or schedule.
Need more guidance on how to stay nourished and hydrated on your hike or backpacking trip? Contact me and let’s review your plan!