This time of year, when Taiwan is hot and humid, physical exertion outside carries with it the risk of dehydration. Since human bodies are composed of somewhere between 60-70% water, maintaining the correct level of those 2 Hs and an O is very important for good health - hell, even simply for staying alive.
Although we can survive up to weeks without food, we hydro-beings die within days if we don't get enough water. Why? Andrea Zaferes puts it succinctly: "Water dilutes and removes wastes and toxins from our body, carries nutrients and oxygen to our tissues, regulates body temperature, lubricates our joints and is crucial for digestion, metabolism, and breathing." Lacking sufficient water, the body is more susceptible to heat stroke.
So how do we lose water? Believe it or not, simply by breathing, we lose a pint of water every day! Of course, sweating and going pee-pee are also important factors in water loss, as are diarrhea, vomiting, physical exertion in hot and humid conditions (in which sweat doesn't evaporate enough to cool the body), and fever.
What does dehydration look like? Check out this chart of symptoms:
Mild (Safe to treat at home as long as it doesn't worsen)
Thirst, dry lips/mouth, dizziness, dry/warm skin, weakness, small amounts of dark, yellow urine, headaches, cramping in the arms/legs, crying with few/no tears.
Moderate (Children under 12 should see a physician immediately)
Extreme thirst, very dry mouth, eyes sunken, sunken fontanel (soft spot on infant's head), lack of elasticity of the skin, low blood pressure, rapid and deep breathing, fainting, bloated stomach
Severe (Requires iv therapy to reverse symptoms)
Seizures, heart failure, rapid breathing, severe muscle tightening in the arms/legs/stomach/back, rapid and weak pulse (often over 100 beats per minute), cold hands and feet, blue lips, person is lethargic/confused.
Preventing dehydration is a simple matter of keeping the body cool and drinking fluids - the right kind of fluids. DO drink 8-10 (8oz) glasses of water (more if you are in the sun or exercising) per day even if you don't feel thirsty, but DO NOT replenish water with beverages such as soda or coffee that contain caffeine. Caffeine is a diuretic, which will cause you to lose more water through urine than you take in through the beverage. Fruit juices contain extra calories, while sports drinks replace electrolytes that may not have been lost in the first place - drink them sparingly!