The GI is a measure of how much a person’s blood glucose increases over the course of two hours after a specific food is eaten. In general (but not always), foods that are sugary or highly processed (like honey, sugar-sweetened cereals, or white bread) have a higher GI, since they are absorbed quickly and cause a sharp rise in blood glucose. Foods that are high in fiber and are consumed in their natural state (like barley, fresh apples, and dried beans) generally have a lower GI because they take longer to digest and cause a slower and lower rise in blood glucose. This is why it’s helpful for people with diabetes to choose foods with low GI values most of the time (a value of 55 or lower is considered low GI).
But, there are some caveats to using the GI for selecting foods. The GI does not take portion sizes into account. The GI is based on 50 grams of digestible carbohydrates in a food, no matter what a sensible portion of that food would be. It takes almost 2¾ cups of plain nonfat yogurt to get 50 grams of carbohydrate (feeling stuffed?), but it only takes a little more than a cup of white rice to get the same amount of carbohydrate.
Another concern with the GI is that the calculations are taken on people who were eating a measured amount of a single food. So, although lentils have a low GI of 28, most people would eat them as part of a meal, perhaps with a slice of whole-wheat bread (GI of 62) and with a banana for dessert (GI of 52). So the total GI for your meal is going to be higher than it would be if you were just eating the lentils alone. Remember, it’s the amount of total carbohydrates in all the foods you eat in a meal that determines your blood glucose response, not just the carbohydrates – or the GI – in a single item.
Just because a food has a low GI doesn’t mean it’s packed with nutrients or good for you – potato chips and some candies have a low GI, and certain wholesome, nutritious foods, such as watermelon, fresh pineapple, and sweet potatoes, have a high GI. As I tell clients, don’t let a high GI value keep you from eating healthy, good-for-you foods!
Other factors that influence the GI are the amounts of fiber and fat in the food, whether the food is raw or cooked, and even the ripeness of fruits and vegetables. For these reasons, the most important focus in meal planning should be the total amount of carbohydrate in a meal, not the GI of individual foods that make up the meal.
If you want to incorporate more low GI foods into your diet, these are some of my favorite options – both savory and sweet, with carb counts included to help you plan meals. Always talk to your diabetes care team about any changes you’re interested in making in your diet.
On the savory side
With a GI of 28 and a reasonable 22 grams* of carbs in a ½-cup serving, barley is a delicious way to add a whole grain to your healthy meals. It cooks quickly, has 3 grams of fiber in a ½-cup, and is a good source of B vitamins. Serve it as a side dish, use it to make a pilaf, or turn it into a salad with chopped vegetables and a splash of vinaigrette dressing.
This creamy dip made with chickpeas and tahini has a GI of just 6! A ¼-cup serving has 9 grams of carbs and almost 4 grams of fiber. I make it a go-to snack along with fresh veggies or whole grain crackers. It makes a great sandwich for lunch, too: Spread it on 100% whole-wheat bread with tomato and cucumber slices for a healthful, filling meal.
This protein-packed snack has a GI of only 7 and just 8 grams of carbs in ¼-cup. Peanuts are a terrific portable snack for keeping in your purse or briefcase for times when hunger hits and there are no healthy options available. Choose unsalted dry roasted or raw peanuts, and remember to count calories – a handful (¼-cup) of peanuts has a whopping 214 calories.
Dried beans and lentils
Foods like black beans, pinto beans, kidney beans, and lentils are some of the healthiest foods I recommend. They are an excellent source of fat-free protein, one of the highest fiber-containing foods, and with only about 20 grams of carbs in a ½-cup serving, they can fit into many meal plans. Oh, yes, and they’re low-GI, ranging from 14 to 30, depending on the variety.
Sweeter low-GI treats
Avoid sweetened yogurt and go for plain low-fat or fat-free yogurt to treat yourself to nutritious breakfast, snack, or dessert. Yogurt has a GI of just 14 and only 9 grams of carbs in a ½-cup serving. If you’re craving something sweet, top your yogurt with ¼-cup of low-GI fruit like fresh cherries, blueberries, or peaches.
Dark chocolate is a delicious sweet secret for people living with diabetes – and not just because it has a GI of just 23. A tiny amount (about ½-ounce) of this intensely flavored chocolate will satisfy a sweet tooth for just 9 grams of carbs and 78 calories.
If you’re craving a sweet but you want a healthy low-GI option, try a small serving of dried fruit. Apricots (GI of 32; 18 grams of carbs in 8 dried apricots), raisins (GI of 54; 14 grams of carbs in 2 tbsp.), and prunes (GI of 29; 24 grams of carbs in 4 prunes) are all nourishing options for a naturally sweet snack.
*All nutrient counts are estimates based on United States Department of Agriculture (USDA) National Nutrient Database for Standard Reference, Release #25; all GI numbers are from glycemicindex.com
Jackie Mills is a registered dietitian who develops recipes for such national magazines as Cooking Light and Family Circle, as well as for books such as the American Medical Association Type 2 Diabetes Cookbook. She was formerly the food editor at Redbook magazine. Mills is a paid contributor for The DX. All opinions contained in this article reflect those of the contributor, and not of Sanofi US, its employees, agencies, or affiliates.
© 2014 The DX: The Diabetes Experience