If you have diabetes, you know all too well that when you eat carbohydrates, your blood sugar goes up. The total amount of carbs you consume at a meal or in a snack mostly determines what your blood sugar will do. But the food itself also plays a role. A serving of white rice has almost the same effect as eating pure table sugar — a quick, high spike in blood sugar. Whereas a serving of lentils has a much slower and smaller effect.
Picking good sources of carbs can help you control your blood sugar as well as your weight. Even if you don’t have diabetes, eating healthier carbohydrate-rich foods can help ward off a host of chronic conditions (heart disease, diabetes, various cancers ).
One way to choose foods is with the glycemic index (GI). This tool measures how much a food raises blood sugar.
What Is the Glycemic Index?
Glycemic index (GI) is a number that gives you an idea about how fast your body converts the carbs in a food into glucose. Two foods with the same amount of carbohydrates can have different glycemic index numbers.
Foods that have a higher GI break down quickly and raise your blood sugar levels rapidly. While the food having a lower GI takes a longer time to get digested and absorbed, resulting in slower and gradual changes in blood sugar levels.
How The Glycemic Index Works
The glycemic index rates the effect of a specific amount of a food on blood sugar compared with the same amount of pure glucose. A food with a glycemic index of 28 raises blood sugar only 28% as much as pure glucose. One with a GI of 95 acts like pure glucose.
The smaller the number, the less impact the food has on your blood sugar.
• 55 or less = Low (good)
• 56- 69 = Medium
• 70 or higher = High (bad)
Using the glycemic index is simple. You should choose foods in the low GI category instead of those in the high GI category (see below), and go easy on those in between.
• Low glycemic index (GI of 55 or less): Most fruits and vegetables, beans, minimally processed grains, pasta, low-fat dairy foods, and nuts.
• Moderate glycemic index (GI 56 to 69): White and sweet potatoes, corn, white rice, couscous, breakfast cereals such as Cream of Wheat and Mini Wheats.
• High glycemic index (GI of 70 or higher): White bread, rice cakes, most crackers, bagels, cakes, doughnuts, croissants, most packaged breakfast cereals.
Important Things to Remember Regarding the Glycemic Index:
The Glycemic index provides information about how different foods affect blood sugar and insulin. The lower a food’s glycemic index or glycemic load, the less it affects blood sugar and insulin levels!
The Glycemic Index Can Change
The GI of a food is simply a starting point on paper but it could be different on your plate, depending on a variety of factors. Some of these characteristics are naturally occurring, whereas others are affected in commercialization or home preparation
Physical form. Generally, the more processed a food, the higher its Glycemic Index (GI). For example, instant oatmeal has a GI of 79, whereas steel cut rolled oats has a GI of 55.
Preparation. Longer cooking times may increase the glycemic impact of a food by breaking down the starch or carbohydrate and allowing it to pass through the body more quickly when consumed. Pasta cooked al dente (for 5–10 minutes) has a slightly lower GI than pasta cooked longer.
Acidity. The more acidic a food is (e.g., pickled food or those containing vinegar or lemon juice), the lower the GI. For example, sourdough bread, which uses a lactobacillus or lactic acid culture as part of the leavening process, has a lower GI than white bread.
Ripeness. The glycemic index of fruits like bananas goes up as they ripen.
Food Combinations. When carbohydrates are eaten as part of a meal, the GI of the meal changes based on the average of all the GI values factored together. You can bring down the overall glycemic index of a meal by combining a high-glycemic index food (such as rice) with foods that have lower ones (such as red beans or legumes).
The Big Picture
Not all carbohydrate foods are created equal, in fact they behave quite differently in our bodies. The glycemic index shouldn’t be the only thing you consider when making choices about what to eat. The fact a food has a low glycemic index doesn’t mean it’s super-healthy, or that you should eat a lot of it. Calories, vitamins, and minerals are still important.