Using The Glycemic Index To Help With Meal Planning: Pros And Cons

One misconception about the glycemic index (GI) is that it measures how quickly blood glucose rises, or spikes after eating different foods. However, speed is not a glycemic index issue.

The glycemic index ranks foods, from zero to 100, based on how they affect blood glucose levels. In the hours immediately following a snack or meal, high-GI foods generate higher glucose levels than low-GI foods.

GI Pros and Cons

Using the glycemic index to guide food choices provides two valuable diabetes management benefits:

1. Carbohydrates from different food sources affect blood sugar differently. Eating 25 grams of potato carbohydrate will raise our glucose more than eating 25 grams of carbohydrate from whole grain pasta. The glycemic index indicates these differences, helping us choose a combination of foods more likely to keep our blood glucose consistent.
2. Overall, a low-GI diet is a healthy one. It consists largely of unprocessed, unrefined, high-fiber fare that digests slowly, including veggies, fruits, whole grains, and some dairy.

Despite these benefits, the glycemic index has a few shortcomings:

• People eat a range of food during meals, and combinations of foods affect blood sugar differently than single food items.
• It does not account for variables that affect blood glucose, such as how a food is grown, prepared, or how much is consumed.
• The foods are not ranked according to nutrient content; a low-GI food can be high in sugar, saturated fat, and calories.

Glycemic index values can also vary somewhat between different GI lists. However, something does not have to be perfect to be useful.

Glycemic Index and Load

Though many people find the glycemic index useful, if we eat too many low-GI foods our glucose level can still become too high. That’s why proponents of the glycemic index generally recommend it be used in conjunction with carb counting. Selecting mostly lower-GI foods ensures the quality of our carbohydrates, while counting carbs prevents us from eating too many of them.

By considering the glycemic index of a food and its grams of carbohydrate we determine the food’s glycemic load—an effective indicator for how a serving of food will affect blood sugar. For instance, a cup of watermelon, and a cup of mashed potatoes each has a high glycemic index, but the potatoes carry a greater glycemic load - and affect blood glucose more - since there are more carb grams in the cup of potatoes.

Big research studies consistently indicate that high-GI foods produce a greater blood sugar response than low-GI foods. So, favoring low-GI foods while keeping track of total carbohydrate grams can be an effective strategy for controlling our glucose levels.

Sources: Mayo Clinic; Tracey Neithercott/Diabetes Forecast
Photo credit: Thomas Morris