The human body is able to tightly regulate your blood sugar levels within a narrow range -- but if you have insulin resistance, pre-diabetes or diabetes, you need to pay more attention to the foods you eat in order to control your blood sugar levels. Although many people know that eating too much sugar, sweets and desserts can cause blood sugars to raise too high -- which can damage your arteries, heart, kidneys and eyes -- it is important to know that starchy foods can have the same effect.
Starches and Blood Sugars
Starchy foods are made of starches, a type of carbohydrate made of a chain of glucose, the type of sugar found in your blood. The chains of starches have different lengths but the bonds linking the molecules of glucose are easily broken down by the enzyme amylase during the digestion process. As a result, the starch found in food is broken down into single units of glucose that your body can easily absorb. Once absorbed, the glucose derived from the starches you eat cause a rise in your blood sugar levels.
Blood Sugar Levels
Ideally, your blood sugar levels should not raise too high after a meal because high concentrations of glucose in your blood can lead to many serious health problems. If you don't have diabetes, your blood sugar levels should not raise above 139 mg/dL two hours after a meal. If your blood sugar levels raise between 140 and 199 mg/dL two hours after eating starchy foods, you are likely to have pre-diabetes, while a blood sugar above 200 mg/dL can indicate diabetes, according to the National Diabetes Information Clearinghouse. Consult your doctor for more testing.
Starchy Foods
Starchy foods are very common in the standard American diet and can easily cause large rises in blood sugar levels. For example, a large baked potato contains close to 60 g of starches, which is the equivalent of 15 tsp. of sugar. Sandwiches, hamburger buns, pizza dough, bagels, bread, corn, pasta, rice, breakfast cereals and baked goods also constitute some of the most common sources of starch. The more starches you eat at a time, the higher the rise in your blood sugar levels after your meal.
Glycemic Index
Although starches used to be called complex carbohydrates, which used to be considered better than simple sugars, it is now understood that a slice of white bread can raise your blood sugar levels just as fast as 1 tbsp. of table sugar. The glycemic index allows to distinguish how quickly and how high starchy foods can raise your blood sugar levels. High glycemic starchy foods, such as potatoes, both white and whole wheat bread, rice, rice cakes, pretzels and most baked goods, quickly cause your blood sugars to spike. Replace these foods with low glycemic index starchy foods, such as whole grain pasta, sourdough bread, Basmati rice, quinoa, barley, beans and lentils.
References
- American Diabetes Association: Carbohydrate Counting
- USDA National Nutrient Database: Nutrient Data Laboratory
- National Diabetes Information Clearinghouse; Diagnosis of Diabetes; October 2008
- "American Journal of Clinical Nutrition"; International Table of Glycemic Index and Glycemic Load Values; Kaye Foster-Powell, et al.; 2002
