How can I prevent dehydration?

Studies have shown that losing as little as 2 percent of your body weight in fluid will adversely affect the function of your circulatory system and decrease performance levels. Thirst alone is a poor indicator of how much water you should be drinking. A good way to keep track of how much you should drink is by first determining your average daily weight. Drink enough water, juice or sports drink during exercise to maintain this starting weight.

Some guidelines for staying hydrated are as follows:

  • Consume 16 ounces of fluid 2 hours before exercise. More may be needed if you’re exercising in warm weather.
  • Drink 20 to 40 ounces of fluid for every hour of exercise
  • If exercise lasts more than an hour, use a sports drink that can replace both fluid, electrolytes and dwindling muscle glycogen stores.
  • Take in 20 ounces of fluid for every pound of body weight lost after exercise.

The first step to avoiding dehydration in exercise is to start with a full tank. Drinking 1 to 2 cups of water in the half hour before exercise is generally enough. Don't force yourself to drink. Your thirst is your best guide. For those who wish to be more scientific about it, you can find out your own sweat rate for a given temperature and exercise intensity. 

This is how you do it:

  1. Weigh yourself (digital scale that goes to the tenth of a pound is best), without clothes (this is important afterwards because clothes can absorb water weight after your exercise).
  2. Exercise for an hour at a similar temperature and intensity as your planned activity.
  3. Weigh yourself after exercise, sans clothes.
  4. Each pound of weight loss equals one pint (2 cups) of fluid.

For example, if you lost one pound in an hour of exercise then that equals 2 cups of fluid. Therefore, you should drink a cup every half hour in your exercise. 

So this gives you how much to drink, but what should you drink?

Well, to understand this we must remember that hydration involves not only water, but electrolytes also. Most important is sodium. Sodium is the most important in hydration and even in muscle cramping. Sports drinks, like the original Gatorade, were developed for a reason. After exercising 30 minutes to 1 hour, electrolyte depletion becomes an issue. Good sports drinks will have sodium chloride as a major ingredient and sugar also, about 15 gm/8 oz. The sugar helps in the absorption of the electrolytes. 

Hydration after exercise is also important, but once again listen to your body (thirst). If you have exercised more than 4 hours, be careful not to drink too much afterwards. This can contribute to low sodium levels, a potential medical emergency.

Avoid dehydration altogether by getting your family to practice good habits:

  • Drink plenty of water before, during and after strenuous activity or exercise, because your body loses lots of water through sweat.
  • Encourage children to drink extra fluids during the summer; have them suck on flavored ice snacks or popsicles as well.
  • Avoid coffee, sodas, caffeinated or alcoholic beverages. These are diuretics, which means they cause the body to lose more liquid through urination.
  • Avoid high-protein diets. Protein requires lots of water to properly metabolize; if you are on a high-protein diet make sure you’re drinking plenty of water.
  • Wear one layer of light-colored clothing (made of breathable fabrics) when working or exercising outdoors. It keeps the sun off your skin and your body cool.
Dr. Ricardo E. Estape, MD
Gynecologic Oncologist

You can avoid dehydration by following a few basic guidelines.

  • Don’t wait until you are thirsty to drink water. Build in hydration breaks at regular times throughout the day.
  • Choose water as your main source of hydration. Sports drinks, juice, lemonade and iced tea are sugar-sweetened beverages that should be limited or avoided. Coffee and other drinks that are high in caffeine content can also cause dehydration.
  • Eat plenty of fruits and vegetables. These foods naturally have a high-water content.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.