Diabetes Meal Planning: Glycemic Index

Over the past few weeks we’ve looked at several common meal-planning approaches for diabetes management. There are other approaches out there, too, including fat gram counting and the use of sample menus. And chances are, you might use your own approach or a hybrid of approaches. The point is that there is no one right way to plan meals when you have diabetes. In addition, some people follow a vegetarian or vegan plan; others may do best when they limit carbohydrate. I encourage you to think about what makes sense for you, based on your food preferences, lifestyle, and how well you’re meeting your blood sugar, blood pressure, and cholesterol goals. If you need help or have questions, seek the advice of a dietitian.

This week, I’ll wrap up the meal-planning series with a look at a meal-planning tool that, to this day, remains somewhat controversial: the glycemic index.

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What is the glycemic index?
Developed in 1981, the glycemic index (GI) is a system of ranking carbohydrate foods based on their effect on post-meal blood sugars. Carb foods are assigned a ranking, or number relative to a reference food, such as white bread or pure glucose.

What does the GI actually mean?
Carb foods are assigned a number from 0 to 100 according to the extent that they raise blood sugar levels. Here’s how the numbering system breaks out:

Low-GI foods (55 or less): These include 100% stone-ground whole wheat bread, steel-cut oatmeal, pasta (surprise!), legumes, Snickers Bars, most fruits and non-starchy vegetables.

Medium-GI foods (56-69): Foods in this category include whole wheat and rye bread, quick-cooking oats, brown rice, couscous, ice cream, raisins, and honey.

High-GI foods (70 or higher): White bread, bagels, popcorn, melons, sweet potatoes, Fruit Roll-Ups, and Russet potatoes are examples of high-GI foods.

Surprised that Snickers Bars have a low GI while melon has a high GI? It’s important to note that the GI is not a measure of how healthy or nutritious a food is. Snickers Bars aren’t very healthy at all, while melons are. For this reason, it’s best not to use the GI (if you do so) as the sole basis for making your food choices.

It’s also important to clarify a common misconception about the GI: that a high-GI food causes blood sugars to peak very quickly while a low-GI food does just the opposite. This is not necessarily the case. However, in general, low-GI foods tend to be digested and absorbed more slowly, producing a more gradual increase in blood sugar levels.

What factors affect the GI?
One of the downsides of using the GI is that several factors can affect its accuracy. Here are a few to consider:

Fat and fiber: These nutrients tend to lower the GI effect of a food. So, a high-GI food, such as a baked potato, with some fat (like butter) will become more of a medium-GI food.

Ripeness: The riper a food, the higher the GI.

Processing: Apple juice has a higher GI than apple sauce, which has a higher GI than an apple.

Cooking method: The longer a food, such as a grain, is cooked, the higher the GI.

Variety: Brown rice has a lower GI than short-grain white rice. Different types of potatoes have different GIs.

What is the glycemic load (GL)?
You may have heard some talk about something called the “glycemic load.” The glycemic index addresses the impact of a particular carbohydrate food on blood sugar levels, but it doesn’t address a key concept: amount of carb consumed. That’s where glycemic load (GL) comes in. The GL of a food takes into account both the GI and the amount of a food that you eat, making it a bit more practical. Remember: It’s not just the type of carb that you eat, it’s the amount, as well. And that’s where GL comes in. The GL of a food is calculated by multiplying the glycemic index by the amount of carb in a food and dividing that by 100.

Low GL: 1–10
Medium GL: 11–19
High GL: 20 or higher

Glycemic considerations
Using the GI and/or GL can seem very appealing. But the reality is that these indices don’t always “behave” as they should. In other words, you might expect that a high-GI or -GL carb food would send your blood sugars sky high; that doesn’t always happen. In addition, you’ve probably not seen too many GIs or GLs posted on food packages. Very few foods in the U.S. have them. And GI/GL food lists can vary, depending on who is publishing them. So, consistency and reliability is questionable. Finally, as I previously mentioned, GI and GL really isn’t about eating a healthful, balanced diet. You still want to focus on eating a variety of foods and consuming the amount of foods that’s right for you. That being said, the GI and GL are tools that you may find helpful as you continue to work on managing your blood sugars.

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