There are three basic types of carbs: (1) starchy carbohydrates (polysaccharides); (2) sugars (monosaccharides or disaccharides) and (3) dietary fiber (polysaccharides). Carbs are one of three main food nutrients: the others being protein and fat.

Starch is a Plant Chemical

Chemically speaking, starch is a white, odorless, tasteless, solid carbohydrate, typically composed of long chains of glucose molecules (1000 or more). The most common forms are amylose and amylopectin. Plants store the energy produced by photosynthesis in the form of starch.

Starch is a Complex Carbohydrate

Because the molecular structure of complex carbohydrates is more complicated, than more simple carbohydrate sugars, like sucrose and glucose, the body cannot metabolize complex carbs into energy as quickly as simple carbs. Result? Complex carbs are not digested and turned into energy as fast as sugars (except for fructose) and therefore keep us full for longer.

Starch is an Intermediate or High Glycemic Index Food

However, the classification of carbs into "simple" or "complex carbs" has been superceded by the Glycemic Index, which rates carbs according to their effect on blood-glucose levels. Many starchy foods (eg. potatoes) are now classified as intermediate or high-glycemic-index foods and should (for best effects on blood-sugar and insulin sensitivity) be eaten in combination with lower glycemic index foods.

Starch in Foods

Starch is found in plant-based foods, especially cereals, bread, potatoes, legumes (beans), pasta and rice, which are all classified as "starchy carbohydrates." Starch is also found in some fruits, vegetables, and in the roots and stem pith of plants.