Where Does Popcorn Fall on the Glycemic Index?

The glycemic index can be a useful tool for estimating the effect a food will have on your blood sugar, but it shouldn't be the only way you plan your meals and snacks. Foods that cause moderate to high increases in your blood sugar, such as popcorn, may also be rich in nutrients your body needs. Popcorn can be a healthy whole-grain snack if you prepare it without added fats or salt.

The glycemic index, or GI, evaluates your body's response to foods that contain carbohydrates. The more dramatic the rise in your blood sugar after you eat a food, the higher that food ranks on a scale of 1 to 100. Your body digests high-GI foods rapidly, which can cause significant fluctuations in your blood sugar. Low-GI or moderate-GI foods are digested more slowly and cause smaller fluctuations. The GI value of popcorn is moderate to high, ranging between 55 and 89, according to data from the Glycemic Index Foundation, with most varieties ranking in the mid-50s to mid-60s. Plain, air-popped popcorn has a lower GI than commercial brands. A number of variables may affect the GI value of popcorn, including the variety of corn, the cooking method and ingredients added during commercial processing.

The starches in corn convert to glucose at a moderate to rapid rate, which gives popcorn its moderate-to-high GI value. However, the GI ranking of a food doesn't necessarily reflect its nutritional value, notes the American Diabetes Association, or ADA. When you prepare popcorn without salt, butter or oil, popcorn is a nutritious, filling snack, the ADA says. The fiber in popcorn promotes healthy digestion and may help you maintain or lose weight by filling you up with low-calorie roughage.

Two cups of air-popped popcorn have 62 calories, 1 g of fat, 12 g of carbohydrates and 2 g of fiber. The fiber in this serving of popcorn amounts to 8 percent of the recommended daily fiber intake of 25 g for women under 50 and 5 percent of the recommended daily intake for men under 50, according to the Institute of Medicine's guidelines. The carbohydrates in air-popped popcorn provide energy without a lot of calories and almost no fat.

If you are using the GI value of foods to monitor your weight or control your blood sugar, combining low-GI foods with moderate-GI and high-GI foods throughout the day can result in a diet with a moderate GI, according to the Glycemic Index Foundation. The foundation recommends eating at least one low-GI food at each meal to balance the glycemic effects of the foods you consume.

Prepare plain popcorn in an air popper to avoid adding extra fat and calories. No-salt herbal seasonings add flavor to popcorn without sodium. When you purchase microwave popcorn, read the nutrition facts label carefully. Some brands of commercially prepared popcorn are high in fat, sodium and calories. If you can't resist popcorn at the movies, take your own air-popped popcorn -- a large bag of buttered popcorn purchased at a movie theater may have as much as 80 g of fat.