Not eating carbs could make you dumber, according to data from the U.S. Institute of Medicine. "Going too low carb can impair brain function and reduce your ability to concentrate properly," says Dawn Jackson Blatner, R.D., author of The Flexitarian Diet.
4) A Slower Metabolism
Fueling your muscles with carbohydrates helps you get through exhausting fat-loss routines. "Your body needs a decent supply of carbs post-workout to keep that burn going as long as possible," says Amy Jamieson-Petonic, R.D., a nutritionist at the Cleveland Clinic.