Bread is airy and porous, which means there’s lots of surface area to come in contact with the enzymes in your digestive tract. Result: the carbs break down into glucose really quickly. Pasta, on the other hand, is more compact, so it takes longer to break down. So, though both are high-carb, pasta tends to have a lower glycemic index. When you do eat bread, your best bet is to pick a loaf that’s denser and has whole bits of grains, kernels and seeds.