Water

Water forms a large part of most of the food we eat and all the beverages we drink. The body is good at regulating its own water content and tells us when we need more by making us feel thirsty. This signal should not be ignored. Even better is to drink enough fluids to prevent feeling thirsty. Required daily water intake varies greatly from person to person, depending on age, level of activity, and environmental factors such as heat. The common recommendation of 8 glasses of water a day is not enough for some people, such as athletes and others who exercise strenuously, and is too much for others, such as older, sedentary adults.