Different foods affect our blood sugar levels differently. Some foods increase our blood sugar, while others lower it. The glycemic index (GI) is a ranking system that ranks foods based on how they influence our blood sugar levels. But, is GI really an effective tool for managing blood sugar or reducing weight?

Read on as we delve deeper into this debate!

What is the Glycemic Index?

The glycemic index, or GI, measures the effects of carbohydrate-containing foods on your blood sugar levels. It is important to maintain normal blood sugar levels because fluctuations can have severe effects on your health. The Glycemic Index ranks foods from 0 to 100 based on how they compare to a reference food—either glucose or white bread. A value of 100 represents the standard: an equivalent amount of pure glucose.

Foods that rank high on the GI scale are ones that are rapidly absorbed and digested, causing blood sugar levels to spike and fluctuate drastically. The lower the GI ranking, the lesser the fluctuations in glucose and insulin levels. This is because the food is digested more slowly.

According to the glycemic index scale, foods that rank 70 or higher are high-GI foods and, therefore, are a less healthy choice. Medium-GI foods are from 56 to 69, while low-GI foods rank 55 or lower.

GI was originally used as a guide to food selection for people with diabetes, with the advice to select foods with a low GI value. The GI scale was invented by Dr. Thomas Wolever and Dr. David Jenkins in 1981 at the University of Toronto. It is an approximate measure of how quickly 50 grams of available carbohydrates in a food raise your blood glucose levels. The available carbohydrate of a food is estimated by subtracting the total amount of fiber from the total amount of carbohydrate.

The idea behind the GI was to prevent obesity and keep energy and blood sugar levels balanced between meals. Thus, GI helps diabetics and obese individuals plan their meals better. It can also be a useful tool for people who might want to reduce their risk of diabetes and heart disease.

List of Glycemic Index Foods

Below are a few examples of foods based on their GI.

Low GI Foods (55 or less)

• Peanuts
• Skim milk
• Chickpeas
• Oatmeal, oat bran, muesli
• Sweet potato, corn, yam, peas, legumes, lima beans and lentils
• Fruits such as apples and grapefruits, non-starchy vegetables and carrots

Medium GI Foods (56-69)

• Whole wheat, rye, and pita bread
• Quick Oats
• Brown, wild or basmati rice, couscous
• Yams
• Banana
• Honey
• Fruit juices

High GI Foods (70 or more)

• White bread or bagel
• Cornflakes, puffed rice, bran flakes, instant oatmeal
• White rice, rice pasta, macaroni and cheese 
• Russet potato, pumpkin
• Pretzels, rice cakes, popcorn, saltine crackers
• Watermelons
• Pineapple

What Affects the Glycemic Index of a Food?

There are several factors that can affect the GI of a food. Some of these are:

• Ripeness and storage time — The riper a fruit or vegetable is, the higher its GI. For example, ripe bananas have a higher GI than unripe bananas.
• Processing — Any sort of processing that changes the form of the food may contribute to changes in GI. For example, juice has a higher GI than whole fruit; mashed potato has a higher GI than a whole baked potato, stone-ground whole-wheat bread has a lower GI than whole wheat bread.
• Cooking method — Cooking and breaking down foods before eating can raise their GI as the body has less processing to do for cooked food. This is because the body can digest cooked food much faster than it can digest raw uncooked food. For example, the GI of soft-cooked pasta is higher than that of al dente pasta.
• Variety — Brown rice has a higher GI than converted long-grain white rice. However, brown rice has a lower GI than short-grain white rice.

Apart from these, the fat and protein content of the food also affects the GI value. The presence of protein and fat in foods may lower the GI. However, it is not advisable to add fat to lower the GI of foods for health reasons.

Is the Glycemic Index really useful?

According to the University of Sydney School of Molecular and Microbial Biosciences, diabetic individuals are better off by following a low-GI diet. Their studies have shown that such a diet helps control weight and keeps blood sugar levels steady.

According to several studies, following a low-GI diet can help you lose weight and prevent chronic disorders such as diabetes and heart disease. In diabetes, the body is unable to produce and/or respond to insulin effectively. This leads to an abnormal metabolism of sugars (carbohydrates), which raises blood glucose levels.

Low-GI food contains more complex carbohydrates. Since complex carbohydrates take more time to get digested by the body, they are slowly absorbed. This prevents blood sugar from spiking. Thus, a low GI diet allows diabetics to control and manage their blood sugar levels much more effectively. 

Read how you can manage diabetes here!

Some other benefits of using GI for choosing foods include:

• Managing body weight
• Increasing the body’s sensitivity to insulin
• Controlling diabetes better
• Lowering the risk of heart attacks
• Managing blood cholesterol levels
• Increasing satiety

However, there is an ongoing debate questioning the relevance of GI in guidance towards a healthy lifestyle.

The four major drawbacks of GI are as follows:

• GI value doesn’t consider individual variation: The degree to which a certain food (and amount) elevates one person’s blood glucose may vary from that of another. This is because GI does not represent a holistic view of how carbohydrates are digested and metabolized in the body. Neither does it account for the metabolic and constitutional difference that exists between different individuals. So, an orange or a bowl of rice may spike your blood glucose significantly, whereas it may have a minimal effect on someone else.
• GI value doesn’t consider the nutritional makeup: There are several foods that are unhealthy but have a lower GI. For example, a vanilla cake with frosting has a GI of 52, whereas beetroot has a GI of 64. This is because GI does not consider the nutritional makeup of foods. The vanilla cake contains fats, which lowers the GI of food. Whether the fat is healthy or unhealthy, it is not a point of consideration. On the contrary, even though beetroot has a higher GI, it contains vitamins, minerals, potent antioxidants, and flavonoids that have great health benefits. 
• GI value doesn’t consider the carbohydrate content: GI measures the type of carbohydrate (slow or fast absorbing) but it does not take into account the total amount of carbohydrate you eat. For example, even though pasta has a low GI value, it is still not recommended for people with diabetes. The issue is with portion size. Eating large portions of any carbohydrate will raise your blood sugar levels.
• GI value doesn’t consider food in combinations: We eat different foods as part of a meal, but GI only measures single-pure foods. For example, the GI of pizza dough is 80, whereas a Pizza Hut Supreme pizza has a GI of 36. This shows that the addition of fats and other food groups (as in the case of pizza) slows down blood sugar elevation, resulting in a lower GI. This proves that GI is not a good indicator of the types of food you should eat.

Thus, choosing low-GI foods is not the solution for making healthier food choices. Also, GI alone does not lead to an increase in blood sugar. The amount and type of food you consume are equally important.

Is Carbohydrate Counting better?

Carbohydrate counting, or carb counting, is a method of calculating the grams of carbohydrates you eat each day. It is generally used by people suffering from diabetes, but it can also be used in general to keep your carbohydrate intake in check.

Several studies have confirmed that the amount and type of carbohydrates you consume have the greatest influence on your blood sugar levels. Studies also show that the total amount of carbohydrate in the food, in general, is a stronger predictor of blood glucose response than the GI value.

According to research, for most diabetics, the first tool for managing blood glucose is generally some type of carbohydrate counting. Using the GI scale may help people with "fine-tuning" their blood sugar management.

In other words, combining GI with carbohydrate counting may provide additional benefits to individuals who want to closely monitor their food choices to achieve their blood glucose goals.

Conclusion

A particular diet or meal plan will not work for everyone. Whether you choose GI or carbohydrate counting, it should help you maintain your blood glucose, cholesterol, blood pressure, and/or weight.

Despite the drawbacks, GI can certainly be a helpful tool for managing your blood sugar levels when combined with healthy eating habits. Choose foods low in carbs, high in micronutrients (vitamins and minerals), protein, and healthy fats. The key is to consume carbohydrates from foods such as vegetables, beans, legumes, and certain fruits, which are much better options than grains, sugar, or pre-packaged food.