NUTRITION HOTLINE: How Much Water?

Q: I’ve heard that athletes can sometimes drink too much water. What is the ideal amount to drink each day? Will drinking too much liquid flush nutrients out of my system?

A: Drinking too much water can cause water intoxication, a dangerous condition where your blood sodium level becomes too low (known as hyponatremia). Symptoms of hyponatremia include feeling tired, light headed, or dizzy. Extreme cases can result in convulsions or coma. Drinking too much water will not flush nutrients out of your system, but over time it can place stress on your kidneys.

The old adage to drink eight glasses of water per day was challenged in a report released by The Institute of Medicine (IOM) in 2004. The IOM report concluded that the majority of people can base their fluid intake on thirst, and that the majority of people are not chronically dehydrated. Children and the elderly may not be able to rely on thirst for adequate hydration. The report concluded most women need 91 ounces of fluids per day, and most men need 125 ounces.

Exercise and hot weather increase fluid requirements. All fluids (including caffeinated beverages, juices, and milk) count towards the requirement, as do foods with high amounts of liquid (soup, ice cream, and anything liquid at room temperature). Try consuming fluids for a day based on your thirst level and see where your intake falls. If it is below the recommended amount I would make an effort to increase it.

For optimum performance, The American College of Sports Medicine (ACSM) recommends athletes consume about 17 ounces of a carbohydrate containing fluid (i.e., a sports drink) two hours before exercise, and on warm days an additional 8 to 16 ounces one hour before exercise. They also recommend checking the color of urine and increasing fluids until urine is consistently light-colored.