Water really does a body good, as will other healthy drinks. "Drink lots of fluids," says Ariane Hundt, a New York City-based personal trainer and nutritionist. "A dehydrated body will slow its metabolism and increase hunger and sluggishness."
Hundt suggests detox teas (by Yogi Tea or Traditional Medicinals, for instance). You can also substitute your sugar-filled soft drink with soda water that has no flavor). They'll give you an energy boost without making you crash.