Stopping power and energy-loss straggling of 197Au, 208Pb, and 209Bi projectiles have been measured in different solids (4</=Z2</=82) in the energy range (100-1000) MeV/u. The experimental results clearly demonstrate the influence of the different charge states of the ions. Because of charge-state fluctuations the energy-loss straggling is up to 7 times larger than the pure collisional straggling. The selected energy domain in combination with the heavy projectiles allows for the first time an unambiguous interpretation of the long-standing problem of charge-changing collisions in energy-loss straggling.