March 15, 2007
Q. On its label, Gatorade A.M., a new sports drink, says it “helps put back the fluids and energy you lose during a full night’s sleep.” Should we lie awake and fret about sleep draining our reserves?
A. Craig Horswill, principal scientist at the Gatorade Sports Science Institute in Barrington, says people lose, on average, about 2 pounds overnight, thanks to urine production, water vapor lost while breathing and sweating, and the liver also loses some of its energy reserves. People regain it all quickly by taking fluids and food, he adds. Despite what the label says, Gatorade’s new “thirst quencher” is not meant to be an eye-opener for layabeds, but a pick-me-up for those exercisers who hit the gym, pool or track soon after rising. Of those early birds, “nearly 50 percent of exercisers aren’t fully hydrated before their workout,” the company claims on Gatorade.com. Horswill says the drink’s breakfasty flavors — orange-strawberry and tropical-mango — may get people to replenish themselves fully. The Gatorade formula’s electrolytes help the body retain the drink longer than plain water, and carbohydrates in the drink provide energy, he says.
Jason Conviser, an exercise physiologist at the Center for Partnership Medicine at Northwestern Memorial Hospital, agrees that the body is dehydrated after a night’s sleep. “But hydration in the morning can be achieved by drinking a glass of water,” he says, and the overnight loss of electrolytes or energy typically is not significant.