Over the past half-century, type 2 diabetes cases in the United States have steadily increased. According to historical evidence, just 1% of American adults had the disease in 1958. By 2020, that number increased to 13%, which accounts for about 34 million people. It is a very serious health problem that needs to be addressed.
One of the key tools that physicians use to manage or prevent diabetes in patients is the glycemic index (GI), which indicates the impact of carbohydrate-containing foods on blood glucose levels. The sale, which was developed in 1981, uses a one to 100 scale. Many people believe the GI scale to be a metric for health nutrition. Glucose, or sugar, has a GI of 100, and other foods fall somewhere on the scale. The number corresponds to how much a food will spike blood sugar levels in comparison to glucose. In practice, it looks like:
- Low GI foods: Foods (assigned values from one to 55) that cause a slow and steady release of glucose into the bloodstream.
- Medium-GI foods: These range from 56-69
- High-GI foods: These rapidly spike blood sugar and crashes in blood sugar levels follow. They rank 70 and higher.
The Problem With The GI Scale
The use of this 40-year-old scale has become controversial among scientists and medical practitioners. GI index ignores several factors that determine how quickly the body digests and absorbs carbohydrates. Other key omissions include how foods are grown, stored, manufactured, and stored. The scale also doesn’t take food combinations and serving sizes into account. The main consideration that experts use is that high-GI foods are less optimal for diabetics, but low-GI foods are optimal. Understanding how foods affect blood sugar is useful, regardless of your diabetic status. The GI scale doesn’t account for other critical factors, and the four reasons below indicate why the scale isn’t the most useful tool for blood sugar-friendly foods.
The GI Of Foods Is Subject To Change
There are a few variables that can modify a food’s GI. Preparation or natural processes, such as the ripening of a fruit, can change the GI of a food. The riper a banana gets, the higher the GI goes. Rice, for example, is an example of a food that has a higher GI when freshly prepared. Once the rice cools and you reheat it, however, the GI decreases. This has to do with the formation of resistant starch in cooked, then cooled carbs.
Portion Sizes Aren’t Considered
It’s no secret that portion sizes in America are quite excessive. The GI scale doesn’t consider how much food people eat in one sitting. GI values were assigned to foods based on a serving of a food that contained 50 grams of carbohydrates. This serving size makes sense for some foods, for example, a cup of cooked white rice that has a GI of about 73 and you get 50 grams of carbs from it. That is a reasonable portion of rice, but the problem lies in how foods differ.
In order to hit 50 grams of carbs from rice milk, which has a GI of 86, you would have to drink four whole cups. Most people don’t consume a quart of rice milk in one sitting, so the drink’s GI may not be meaningful. Portion sizes reveal a more accurate picture of how specific foods impact blood sugar during a meal. That is why the glycemic load was created. Unlike GI, the glycemic load accounts for the glycemic index and the portion of the food you eat. Watermelon, for example, is high on the GI scale at 76, but it is low in terms of the glycemic load of eight, when you consider the portion size.
Some High-GI Foods Are Very Nutritious
If you only focus on the GI of a food, you are most likely overlooking other key nutrients that it offers. High-glycemic foods, such as whole grains like oats, contain beneficial fiber that acts as a physical barrier that slows the release of sugar into the bloodstream. Even though a banana may have a higher GI, it also contains potassium, magnesium, fiber, vitamin C, and vitamin B6. Now, the pendulum also swings the other way. Not all foods that have lower GI numbers are optimal choices for your health. Potato chips, for example, have a lower GI than a bowl of oatmeal and sweet potatoes. Those potato chips are rich in saturated and trans fats, excess sodium, and other processed ingredients, whereas the oatmeal and sweet potatoes contain more nutrients, less fat, and more fiber.
It Focuses On One Macronutrient
In addition to GI’s other shortcomings on this list, the final one is that it focuses on a singular macronutrient: carbohydrates. The GI scale doesn’t look at the complete nutritional profile of a meal. People tend to eat carbs like potatoes or rice with other foods, not on their own. If you pair starches with other foods like lean protein sources and green vegetables, for example, you mitigate how quickly the body digests those starches. That means that the time it takes to raise blood sugar levels is much slower. Eating carbohydrates on their own can spike blood sugar levels in a much more dramatic way than if you consume them with healthy fats, fiber, and lean protein. Approximations of a full meal’s GI are often 50% over the actual value, according to researchers.
The GI scale is very subjective and nuanced, and learning to consider other factors of nutrition can be highly beneficial. Don’t simply look at food through the GI lens because it may cause you to focus on the wrong foods.