How do you know you are dehydrated?
People generally refer to dehydration as a reduction in body water below normal levels. The first thing you'll probably experience is thirst. There is not a real precise relationship to how thirsty you feel and how dehydrated you are. Usually when you get the sensation of thirst, you're already somewhat dehydrated. You may get a headache. You may feel dryness of the mouth. If you are exercising or changing posture, you could feel dizzy. If you are in hot weather or exercising in the heat, you may feel hotter. Your skin may feel warmer. You would be urinating less frequently and smaller volumes, so your urine would be dark in color because it would be more concentrated.
There is also some evidence that both your physical and mental performance capabilities decrease as a result of dehydration. You may not be as sharp in terms of some of the types of complex cognitive functions that you have to do. So there are a variety of symptoms.
How can dehydration affect one's health?
Acute dehydration will increase your risk of heat exhaustion and heat stroke. [Heat exhaustion causes heavy sweating, fainting and vomiting, and heat stroke occurs when the body temperature rises to 106ºF or above.] Although it is not as well studied, there is evidence that shows that chronic dehydration can have a variety of different affects on chronic diseases, including urinary tract infections, and kidney stones and gallstones. Some evidence indicates that dehydration may be related to susceptibility to bladder and colon cancer. But that evidence is not real strong.