The fundamental design of a sports drink is to replenish what you've lost through strenuous exercise, and it's for those working out in the heat.
A combination of carbohydrates, sodium, potassium and chloride are greatly reduced with excessive sweating or when the flu hits you hard.
Those minerals are needed to help maintain muscle and nervous system function.
Commercial beverages provide them, but they can contain artificial colors and more sugar than needed - often 2 to 5 teaspoons per 8-ounce glass, not the bottle, which obviously has even more.
So why not make it yourself? We used a recipe from the April 2011 edition of Consumer Reports on Health.
Water is the main ingredient. Fill a pitcher with four cups. Mix that with 2 tablespoons of sugar, half a teaspoon of salt and a squeeze of lemon.
The result is a sports drink that calorie-wise will only cost you half of the brand name sports drinks.
The homemade version is 25 calories per 8-ounce serving versus 50 to 80 calories for a regular sports drink.
If you're looking for a potassium boost as well, add a cup of orange juice to your pitcher, increasing your rehydration beverage to 42 calories per glass.
If you're not big on orange juice, but you still want to ramp up your potassium, grab a few potassium-rich foods like an apricot, a few figs, or a banana.
It's important to note that experts recommend these drinks for those who are exercising at high intensity for more than 90 minutes.
That half-hour workout on a cardio machine at the gym doesn't qualify. Water is your best bet there.