7. Your coffee is a source of water.
Although once thought to have a diuretic effect, current research indicates coffee (in amounts normally consumed) hydrates as well as water over a 24-hour period. That is, after drinking coffee, you may urinate sooner, but you will not urinate more than you consume.
Army research on caffeine and dehydration confirms coffee is an acceptable source of fluids for athletes, even during exercise in the heat. Hence, coffee and other caffeinated beverages such as tea or cola count towards your water intake.
More: 4 Ways to Stay Awake Without Coffee
8. An increased concentration of particles in your blood triggers the sensation of thirst.
If you are a 150-pound athlete, you'll start to feel thirsty once you've lost about 1.5 to 3 pounds of sweat (1 percent to 2 percent of your body weight). You are seriously dehydrated when you have lost 5 percent of your body weight.
9. Body water absorbs heat from your muscles and sweat dissipates heat.
The evaporation of 1 liter (about 36 oz.) of sweat from the skin represents a loss of about 580 calories. Sweat keeps you from overheating during exercise and in hot environments.
10. You can measure your water losses after a workout.
To determine how much water you lose when you sweat, weigh yourself (with little or no clothing) before and after one hour of hard exercise with no fluid intake. The change in body weight reflects sweat loss. A one-pound drop in weight equates to loss of 16 oz. of sweat. A two-pound drop equates to 32 oz.—that’s 1 quart. Drink accordingly during your workouts to prevent that loss.
More: What Does Your Sweat Taste Like?
11. When you sweat, you lose water from both inside and outside your cells.
The water outside the cells is rich in sodium, an electrolyte that works in balance with potassium. Potassium is an electrolyte inside the cells. Sweat contains about seven times more sodium than potassium, hence sodium is the most important electrolyte to replace during extended exercise.
12. Dehydration can hinder athletic performance.
Athletes who lose more than 2 percent of their body weight (3 pounds for a 150-pound athlete) lose both their mental edge and their ability to perform optimally in hot weather. Yet, during cold weather, you are less likely to experience reduced performance, even at 3 percent dehydration.
Three to 5 percent dehydration does not seem to affect muscle strength or performance during short intense bouts of anaerobic exercise, such as weight lifting. But distance runners slow their pace by 2 percent for each percent of body weight lost through dehydration. Sweat loss of more than 10 percent body weight is life threatening.
13. Water can reduce constipation and help with urinary tract infections.
There is also no scientific validation of theories that excessive water intake will improve weight loss, remove toxins, or improve skin tone.
14. You don’t need eight glasses of water per day.
No scientific evidence supports the “eight glasses per day” rule, so you can simply drink in response to thirst. You can also monitor the volume of your urine. If your urine is scanty, dark, and smelly, you should drink more. If you have not urinated during your work or school day (8 a.m. to 3 p.m.), you are severely under-hydrated.
15. Bottled water is not always better than tap water.
According to the Center for Science in the Public Interest, nearly half of bottled waters come from municipal water supplies—not from the mountain streams pictured on the labels. This suggests standard municipal tap water is high quality.
Rather than spend money on bottled water, turn on your tap. This will help stop the flood of 95 million plastic water bottles that get discarded each day, of which only 20 percent get recycled. Drink plenty of water—but think “green.”
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