Adequate hydration is important. Water is a critical nutrient. A general rule of thumb is eight, eight ounce glasses per day. The reality is that there is no universal requirement for water intake, and your needs will vary based on age, gender, body size, health status, and physical activity. Environmental factors like high temperature and humidity levels, also influence water needs.
It is true however that water is involved in every cellular process in your body including your metabolism. So dehydration helps the body to run less efficiently and stalls the metabolism which is simply a series of chemical reactions taking place within the body. Staying hydrated keeps those chemical reactions running smoothly.
Those who suggest drinking only when thirsty are ignoring the fact that it is difficult for the body to tell the difference between hunger and thirst. Sometimes when you think you are hungry, you might simply be dehydrated, so instead of snacking, try drinking a glass of water. One study found that people who drank water before meals ate an average of 75 fewer calories at each meal. That may not sound like a lot — but 75 calories a day over 365 days means that even if you only drink water before dinner every day, you’d consume 27,000 fewer calories over the course of the year. That’s almost an eight-pound weight loss.
The question often arises, is it possible to drink too much water?
Yes. People with certain health conditions can put themselves at risk of complications if they drink too much water. Some heart conditions, high blood pressure, swelling of the lower legs [edema] need and diabetes often require avoiding excess water. Also, drinking too much water while eating can dilute your stomach acid and cause digestive problems.