Via Webmd.com [sic]
A SLUGGISH WORKOUT Muscles need sugar for fuel, so carbs (which break up into glucose, a type of sim-ple sugar) can kick-start your morning jog. But fruit or prepackaged snacks touting “natural sweeteners” contain just fructose, which is metabolized in the liver, not the muscles. The result: bloat, or even the runs.
THE FIX A glucose-packed snack with just 4 to 8 grams of fructose—it’ll help increase glucose absorption, says Dr. Richard Johnson, professor of medicine at the University of Colorado, Denver. Try a sports drink like Gatorade or trail mix with dried fruit an hour before your workout.
Full article here.