Whole grain bread also has a lower glycemic index, providing you with a steadier, more sustained source of energy that lowers your risks of type 2 diabetes, heart disease and weight gain. Whole-grain bread can't be identified by color or name -- bread that's brown in color or labeled "wheat bread," "hearty grain" or "9 grain" may not be a whole-grain product at all. Look at the ingredient list when shopping for whole grain bread. The first ingredient must be a whole grain, such as whole wheat, whole oats or whole rye.

Source livestrong.com