Why it's a mistake: A 12-ounce bottle of G Series Pro Gatorade contains 330 calories. That's almost as many calories as a serving of Ben & Jerry's Peanut Butter Cup ice cream! Unless you're working out intensely for hours, a sports drink isn't necessary.
What you should do: If you're doing a regular 30- to 60-minute workout, rehydrate with good old-fashioned water. If you're concerned about replacing lost electrolytes, go for calorie-free SmartWater or low-calorie coconut water. Save the sports drinks for longer, more intense workouts.