How Can I Tell When My Body Is Hydrated?

Staying hydrated is important to maintain normal body functions and general wellness. Signs of hydration can be identified by monitoring water input and output, especially during activity or warm weather. Awareness of dehydration symptoms helps to determine if your body is hydrated.

According to a 2016 paper published in the American College of Sports Medicine's ACSM's Health and Fitness Journal, muscle contains up to 75 percent water, and fat tissue is made up of 10 to 40 percent water. Cells are composed mainly of water and use water to transport nutrients and other materials. Water assists with all stages of digestion and provides lubrication for joints, which impacts all types of physical activity.

Regulating the input and output of water is the key to maintaining proper hydration. The body requires water for basic metabolism, organ function and osmoregulation — maintaining the balance of water and electrolytes in cells. The body loses water through sweating, respiration and output from the kidneys and gastrointestinal tract.

When water output is greater than water intake, blood pressure drops and starts a physiological chain reaction that triggers thirst and decreases urine production. Factors that impact water output include:

• Air temperature
• Humidity
• Duration of activity
• Intensity of activity
• Increased respiration

Men require 13 cups of fluid per day to maintain hydration, and women require an average of 9 cups per day, according to the ACSM. Fluid intake includes water, juices, coffee, milk and any other beverages consumed. For most healthy adults, this translates to 4 to 6 cups of water per day, in addition to consuming fluids from other sources and eating thirst-quenching foods like fruits, vegetables, soups and yogurt.

Urine that is clear and light in color is one indicator that the body is properly hydrated. Body weight loss after exercise is common and may indicate that you are taking in enough fluids. Adequate hydration results in less than 1 percent weight loss from your pre-workout weight, while a weight loss greater than 1 percent may be a sign of dehydration.

People who are extremely active sweat more and place greater demands on their muscles than people who are less active. They need more than the average amount of water to maintain hydration. A two-hour workout may require drinking up to a gallon of water that day to avoid dehydration.

Read more: Dehydration: Water vs. Gatorade

Thirst is often the first sign of inadequate hydration. Other common symptoms of dehydration include fatigue, lethargy, dizziness, confusion and urine that is darker than normal. Dehydration can be a serious problem for older adults because the sensation of thirst diminishes with age.

According to ACSMs Health and Fitness Journal article_,_ a decrease in water input or an increase in water output can result in a slight impairment in cognitive functions. A 1 to 2 percent water loss can result in mild dehydration that has a negative effect on mood, critical thinking, short-term memory and reaction time.

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Infants' main source of water intake during the first year of life is from breast milk or formula. Sufficient fluid intake is determined by urine output and adequate weight gain. The American Academy of Pediatrics states that babies should wet at least five to six diapers per day after the first couple of days following birth,

The ACSMs Health and Fitness Journal article states that toddlers between the ages of 1 and 3 need to take in about 4 cups of fluids per day to meet their hydration needs. The fluid requirement rises to 5 cups per day in children who are 4 to 8 years old.

According to the Mayo Clinic, infants and small children have a higher ratio of surface area to volume, which causes them to lose water through their skin more quickly than adults. They are especially at risk for dehydration from fever, diarrhea and vomiting. Without verbal cues, parents must rely on other signs of dehydration in toddlers and infants such as lack of tears, unexplained irritability, dry lips, a sunken soft spot and going three or more hours without wetting a diaper.