Water & fluid guidelines:
Follow your thirst. Thirst is actually a good indicator of whether or not you need fluids. An exception to this is older people who can become fluid deficient quickly, particularly in hot weather.
Weigh yourself after your workout. Wouldn't it be nice if that weight you sweat off wasn't just sweat? If your workouts are intense, you might find you've lost several pounds afterwards. Drink 16 ounces of water for every pound lost during exercise to replace what you've lost.
Check your urine. When you are well hydrated, your urine should be pale to clear. This is the best way to tell if you've had enough water. Don’t drink excessive fluids beyond this. If your urine is dark or very small in volume, then you need more fluids!
The 8-cups of water myth. While the average fluid lost from our bodies does turn out to be around 8 cups a day, you don’t need to replace all of it with plain old water. We get water replacement from fruits, vegetables, and other beverages such as milk, tea, soda, and yes, even coffee! However, water is the best fluid for boosting body fluids because it is absorbed the fastest of all the fluids!
Beth Kitchin PhD RDN
Assistant Professor, Nutrition Sciences
University of Alabama at Birmingham