Water makes up, on average, 60 percent of a person’s body weight. This simple substance plays many roles: It helps flush out toxins, transport nutrients to cells, and regulate body temperature, among other essential functions. Since you lose about 10 cups of water a day through breathing, perspiration, urination, and sometimes diarrhea, fever, or vomiting, you must replenish that amount of fluid daily. But when you lose more water than you take in, that leads to a deficit called dehydration.

The first signs of dehydration include a dry mouth, fatigue, thirst, headache, dark-colored urine, and dizziness or light-headedness. These mild or moderate cases can be reversed by simply taking in more fluid. Severe dehydration is much more serious and can cause the body to go into life-threatening shock. Symptoms include low blood pressure, rapid heartbeat, fever, sunken eyes, extreme thirst and confusion, and shriveled or dry skin. An oral rehydration solution or, in more serious cases, an intravenous solution may be necessary.

To prevent dehydration, experts recommend drinking at least 8 cups of water a day. Solid food supplies about 20 percent of your water intake; a rare steak, for instance, is about 70 percent water, while some fruits and vegetables, such as watermelon and tomatoes, are more than 90 percent water. Certain situations require additional water intake. Hot or humid weather; pregnancy or breastfeeding; and illnesses that cause fever, diarrhea, or nausea all lead to additional fluid loss. Sweat-inducing exercise may also raise the risk of dehydration; for short workouts, take in an additional 1 to 3 cups of water. Intense exercise that lasts for longer than an hour may require drinks that contain additional sodium to replace what’s lost in sweat.

ADDITIONAL FACTS

  1. Beer, wine, colas, and coffee can contribute to overall fluid intake, although they shouldn’t make up a significant portion.
  2. When people are removed from life support, they usually pass away from dehydration.