Whole Grains are the best grain sources of carbohydrates. Why?

Whole Grains are the best grain sources of carbohydrates. Why?

Info source: http://www.hsph.harvard.edu/nutritionsource/pyramid-full-story/#Dietary-Guidelines-in-the-21st-Century

The body uses carbohydrates mainly for energy, and it can get them from many sources—some healthful (beans, vegetables, fruit, whole grains), and some not (sugary sodas and other drinks, sweets). 

The best grain sources of carbohydrates are whole grains such as oatmeal, whole wheat bread, and brown rice. 

They deliver the outer (bran) and inner (germ) layers along with energy-rich starch. The body can’t digest whole grains as quickly as it can highly processed carbohydrates such as white flour. 

This keeps blood sugar and insulin levels from rising, then falling, too quickly. Better control of blood sugar and insulin can keep hunger at bay and prevent the development of type 2 diabetes and heart disease.