The glycemic index, or GI, ranks carbohydrate-rich foods on a numerical scale based on how much they raise, or don't raise, your blood sugar levels. The GI diet was first created as a tool to help diabetics control blood sugar levels, but once people realized the diet led to weight loss, it morphed into a weight-loss diet, too. GI-based diets recommend you focus on foods and drinks with a low GI and limit foods with a high GI.
What Affects Ranking
Several things affect the GI of a food. Foods with a lot of fat and fiber tend to have a lower GI than foods that are highly processed. Ripeness also affects the GI of a food – the riper a fruit, the higher its GI tends to be. How a food is cooked and how long also affect the GI. For example, al dente pasta has a lower GI than soft pasta.
High GI foods are digested quickly, so eating theses foods causes a rapid, dramatic increase in blood sugar levels. The spikes in blood sugar caused by high GI foods send signals to your pancreas telling it to release lots of insulin, the hormone that carries glucose to your cells. These high insulin levels lead to dramatic drops in blood sugar, which can cause hunger cravings and lead to overeating. On the flip side, low GI foods are digested slowly. As a result, blood sugar levels are raised gradually and remain steady for a longer period of time, delaying hunger and helping prevent overeating.
Glycemic Index Ranking
Foods are ranked on how they affect your blood sugar compared to the standard, glucose, which has a glycemic score of 100. Foods with a score of 55 or less are considered low-glycemic. Examples of low GI foods include 100-percent stoneground whole wheat bread, pumpernickel bread, old-fashioned oats, oat bran, sweet potatoes, corn, beans, peas, legumes, lentils, non-starchy vegetables and most fruits. Foods with a glycemic index between 56 and 69 are considered medium GI foods and include regular whole wheat bread, rye bread, pita bread, quick oats, brown rice, wild rice and couscous.
Foods with a glycemic score of 70 or higher are considered high GI. White bread, instant oatmeal, white potatoes, pretzels, white rice, white pasta and rice cereal fall into this category.
Weight loss is one of the major proposed benefits of a GI diet, but the perks don’t stop there. Another benefit of following a low GI diet is that keeping your blood sugar levels steady can reduce your risk of developing insulin resistance, a condition that can eventually turn into Type 2 diabetes. A low GI diet can also reduce your risk of other chronic diseases, like heart disease.
Lindsay Boyers has a Bachelor of Science in nutrition from Framingham State College and a certificate in holistic nutrition from the American College of Healthcare Sciences. She is also a licensed aesthetician with advanced training in skincare and makeup. She plans to continue on with her education, complete a master's degree program in nutrition and, ultimately, become a registered dietitian.