An hour of exercise can lead to up to a quart of water lost through sweat, depending on the type and intensity of your workout and how hot the temperature is while you're exercising. This fluid needs to be replaced to help you avoid dehydration. In many cases, water is all you need to rehydrate your body. People who exercise for more than 45 minutes or in very hot temperatures, however, may need a beverage containing electrolytes such as potassium and sodium.
Drinking a few ounces of water every few minutes while you are exercising can help you stay hydrated without developing a sloshing feeling in your stomach. Aim for 8 ounces for each 10 to 20 minutes you exercise, and then drink another 8 ounces of water within half an hour of finishing your workout, recommends an article on the Columbia University Health Services website.
If you participate in endurance sports or resistance training, you may want to try low-fat milk as a rehydration beverage. According to an article published in the "Journal of the International Society of Sports Nutrition" in 2008, it helps improve the formation of muscles and rehydrates just as well as commercially available sports drinks. Endurance athletes who drank chocolate milk as a recovery beverage had increased muscle-building activity and greater time to exhaustion than those who drank a carbohydrate-based sports drink in a study published in "Medicine and Science in Sports and Exercise" in April 2012. Only use low-fat chocolate milk if you participate in an exercise that involves constant, sustained movement, such as long-distance running, swimming and cycling, because otherwise you don't need the extra calories and carbohydrates.
Sports drinks come packed with beneficial electrolytes, and they're best for after long and strenuous workouts. Short workouts don't usually cause you to lose enough electrolytes to need these beverages. Look for one that has no more than 14 grams of carbohydrates and no more than 50 calories in a serving, recommends the AARP website. Watch your calorie intake if you opt for sports beverages -- you could end up taking in almost as many calories as you burned during your workout.
If you don't like plain water but aren't participating in long workouts, a flavored water with no more than 10 calories per 8-ounce serving can help you rehydrate without consuming too many calories. Another relatively low-calorie option is unflavored coconut water, which can help replace some electrolytes but doesn't necessarily rehydrate you any better than water, according to registered dietitian Sharon Denny in an article on the Academy of Nutrition and Dietetics website.