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4 Reasons to Stay Hydrated This Summer


Most people are familiar with the health dangers of extreme dehydration. Less well-known is chronic mild dehydration. This can have a measurable detrimental effect on mental and physical performance, muscle growth and even long-term health.

Woman drinking water

Here are the top four reasons why hydration is so important:

Muscles Need Water to Function
Since muscles are around 70 percent water, even a small loss of fluid will affect their function. Furthermore, nerves control muscles: The electrical stimulation of nerves and contraction of muscles occur due to the exchange of electrolytes dissolved in water across the nerve and muscle-cell membranes. If you're low on water or electrolytes, this weakens muscle strength and control. A water deficit of just two to four percent of your body weight can cut your strength-training workout by as much as 21 percent and your aerobic power by a whopping 48 percent.

Water Dilutes Toxins
When your goal is to lose body fat, water is your friend. It can help take the edge off hunger so you'll eat less. If you are on a high-protein diet, water is essential for flushing out ammonia, a byproduct of protein-energy metabolism. As you mobilize your stored fatty acids to burn off as energy, you release any fat-soluble toxins that have been benignly stored in your fat cells. The more fluid you drink, the more dilute the toxins in your bloodstream and the more rapidly they leave your body.

Brains Need Water Too
When it comes to peak mental capacity, your hydration state will affect your performance. In a study, the subjects' abilities to perform mental exercises after heat-stress-induced dehydration, which is a fluid loss of only 2 percent of body weight, caused reductions in arithmetic ability, short-term memory and the ability to visually track an object compared to their well-hydrated states.

Water Can Prevent Kidney Stones
Probably most surprising is the effect that chronic mild dehydration has on health. Nearly 12 to 15 percent of the general population will form a kidney stone at some time in their life. Many factors can modify the urinary risk factors for developing stones. Of these, diet -- especially fluid intake -- is the only factor that can be easily changed and that has a marked effect on all urinary risk factors.

Your Fluid Plan
Design a fluid plan that is convenient to take advantage of throughout the day: two cups in the morning, a few more midmorning, a couple at lunch, again in the midafternoon and at dinner. That covers your minimum intake. Then add what you need to be well-hydrated before, during and after exercise.

Many factors increase water requirements, including high heat, low humidity, high altitude, exercise, dieting, illness, travel and pregnancy. Make it a goal to carry water and fluids with you as a constant reminder to stay hydrated. Don't forget that fruits and vegetables are great sources of water as well.

Symptoms of Dehydration

Mild Symptoms
Loss of appetite
Flushed skin
Burning in stomach
Dry mouth
Dry cough
Heat intolerance
Dark urine with a strong odor

Severe Symptoms
Difficulty swallowing
Shriveled skin
Sunken eyes and dim vision
Painful urination
Numb skin
Muscle spasm

Fluid Guidelines
*Drink a minimum of one quart (four cups) of fluid for every 1,000 calories you eat every day.
*Drink at least five cups of water every day.
*Drink cool fluids.
*Drink two cups of fluid two hours before exercise.
*For moderate exercise that lasts an hour or less, water is sufficient for replacing lost fluids. If you like flavored drinks better, then drink those.
*For intense exercise that lasts less than an hour and moderate exercise lasting more than an hour, carbohydrate-replacement sport drinks are best.
*If you exercise moderately, drink according to thirst. If you race to win, drink four to six ounces every 15 to 20 minutes during exercise.
*After exercise, drink 16 to 20 ounces (two to two-and-a-half cups) of fluid for every pound of body weight lost during exercise.
*Caffeine in moderate amounts (75 to 80 milligrams) may enhance performance without causing dehydration.


-- Dr. Susan Kleiner

Readers -- How much water do you drink during the day? What other liquids do you drink throughout the day? Have you ever experienced mild dehydration? Do you suffer any of the symptoms listed above when you haven't had enough to drink? Leave us a comment below and let us know.

Dr. Susan Kleiner, Ph.D., RD, FACN, CNS, FISSN, is a high-performance nutritionist and foremost authority on nutrition for strength and power. In addition to her Ph.D. in sports nutrition, she's a founder and fellow of the International Society of Sports Nutrition, fellow of the American College of Nutrition, and the best-selling author of numerous books, including “Power Eating,” written specifically for athletes to build muscle, gain energy and cut fat. As a nutritional consultant for USANA, she uses her extensive knowledge in sports nutrition to help support the health of hundreds of professional athletes and active individuals who use USANA products.

Connect with Dr. Kleiner on her website or on Facebook and Twitter.

Kleiner, SM. "Water: An essential but overlooked nutrient." J Am Dietet Assoc 1999(99): 200-206.

American Dietetic Association, Dietitians of Canada, American College of Sports Medicine. Nutrition and Athletic Performance. Joint Position Statement. Med Sci Sports Exerc 2009 41(3): 79-731.

Pelletier C, et al. "Associations between weight loss-induced changes in plasma organochlorine concentrations, serum T3 concentration, and resting metabolic rate." Oxford J Life Sci Med Toxicol Sci 2002 67(1): 46-51. doi: 10.1093/toxsci/67.1.46



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