Does your body run best on 8 glasses of water a day? Not necessarily. Everyone has different fluid needs. The weather--both temperature and humidity--plays a part and so does your size, gender, and level of activity. So, are 8 glasses of water a day really linked with good health? Some say 8 glasses of water helps with weight loss. That wasn't true of 38 overweight and obese teens though, who were asked by researchers to drink more water for six months. Those researchers