JULY 9, 2025 – The average human body comprises just over half water, so ensuring you stay hydrated throughout the day is essential to medical and mission readiness.
Water is one of your body’s most important nutrients for optimal function, according to the Consortium for Health and Military Performance at the University of Uniformed Services, otherwise known as CHAMP. Sweating and inadequate fluid intake can combine to cause dehydration, which can affect a service member’s job performance, health, and safety, as well as overall unit readiness—and it’s a controllable risk factor. Loss of 2% of body weight due to sweating can also impair physical performance and increase risk of heat illness, according to U.S. Army Lt. Col. David DeGroot, co-director of Warrior Heat- and Exertion-Related Events Collaborative at CHAMP.
CHAMP provides human performance resources for warfighters to maintain optimal readiness—with tools to monitor your hydration and tips to make sure you replace the fluids you lose.
What is Dehydration?
Dehydration occurs when the body loses more fluid than it takes in. Hot environments and extended periods of activity or outdoor operations can greatly increase the risk of dehydration due to sweat loss.
Top seven ways to combat dehydration:
1 – Use the WUT Method—a combination of three indicators (weight, urine, and thirst) to accurately estimate hydration status:
- Weight: Check the scale before and after an event. When you replace water losses throughout the day, your body weight should change by less than 1%. Two percent or more of weight loss is a marker of dehydration.
- Urine: Check your urine color. When well hydrated, your normal urine color is “very pale yellow,” “pale yellow,” or “straw-colored.” Dark urine color is a marker of dehydration. Decreases in urine volume and urination frequency are also indications of dehydration.
- Thirst: Check in with your body. An increased level of thirst is a marker of dehydration.
2 – Understand symptoms of thirst:
- Dry mouth
- Dizziness/Lightheadedness
- Apathy
- Nausea
- Headaches
- Gastrointestinal Cramping
- Discomfort
3 – Take steps to consume fluids:
- Rehydrate. Your goal is to replace any fluid and electrolytes lost.
- Beverages that contain carbohydrates and electrolytes stimulate thirst, retain fluid, and promote rehydration.
- Consider consuming sports drinks, milk, or salty foods.
- Be careful not to overdrink, if you consume too much fluid, hyponatremia (low sodium levels in the bloodstream) can occur.
- Ask for help if you develop severe symptoms.
4 – Prevent dehydration:
- Drink an average of eight cups or half your body weight in ounces of water each day.
- Warfighters’ water intake are men should consume 12-18 cups, while women should consume 8-12 cups of water.
- Use the WUT method to fine tune your individual fluid replacement needs.
5 – Strategies to Stay Hydrated:
- Carry a good-quality water bottle all day.
- Sip do not chug! Take small sips of fluids frequently throughout the day.
- Add lemon, lime, berries, or cucumber to the water for flavor.
- In hot or humid environments, add sodium.
- Set a timer to remind yourself to drink at regular intervals.
- Eat foods with high water content, such as melon, cucumbers, grapes, or tomatoes.
- Choose other nutrient-dense fluids, such as milk, milk alternatives, 100% vegetable juice, or unsweetened tea.
- Drink fluids with electrolytes.
6 – Choose the Right Beverage for Hydration:
- Water: Plain or carbonated. Water is the best option for exercise less than 60 minutes and for all-day hydration.
- Milk: Plain or flavored low-fat milk, for recovery after intense or long workouts.
- Sports drinks: Best for exercise or training regimens longer than 60 minutes.
7 – Using CHAMP’s guidelines for physical activity hydration:
- Before: Drink 14–22 oz of fluid 2–4 hours before exercise.
- During: Drink 16–32 oz of fluid every 60 minutes during exercise.
- After: Drink 20–24 oz of fluid for every pound lost during exercise.
Even as little as 2% dehydration is enough to affect both your physical and mental performance negatively. Use these tips from CHAMP to stay operationally ready and fit.
Resources
If you want to learn more about optimizing mission performance and health through nutrition, visit the Uniformed Services University of the Health Sciences Consortium for Health and Military Performance. Here you can explore dozens of nutritional fitness tips, articles, and other references for better nutrition to enhance readiness. To take your nutrition goals to the next level, contact your local military hospital or clinic and request a consultation with a nutritionist or a dietician.
Story by Robert Hammer
Office of the Assistant Secretary of Defense for Health Affairs/Military Health System