IS THE GLYCEMIC INDEX IMPORTANT IN 2024? Or is it Outdated?

To understand my answer, I need to explain the glycemic index, fiber, and processing:

What is the glycemic index?

By definition, the glycemic index is a measure of the blood glucose raising potential of the carbohydrate content of a food compared to a reference food (generally glucose).  This number can give you an idea of how fast your body converts the carbs (the plant kingdom) in a food into glucose. In other words, some foods can be rapidly absorbed and therefore rapidly increase blood sugar.

Additionally: Two foods with the same amount of carbohydrates can have a different glycemic index. And even more important, the fact that a food has a low glycemic index doesn’t mean it’s healthy (e.g., potato chips have a lower glycemic index than oatmeal and about the same as green peas). But oatmeal and green peas have more nutrients.

The Reason: Carbohydrates like refined sugars and white bread are easier for your body to change into glucose, the sugar your body uses for energy, then more slowly digested carbs like those in vegetables and whole grains.

Does fiber affect the glycemic index?

Dietary fiber includes the parts of plant foods your body can’t digest or absorb. Unlike other food components, such as fats, proteins, or carbohydrates — which your body breaks down and absorbs — fiber isn’t digested by your body. Instead, it passes relatively intact through your stomach, small intestine, and colon and out of your body.

Dietary fiber can contribute to a reduction in the glycemic index.

In a National Library of Medicine Article, the authors write, “It was concluded that dietary fiber is associated with decreased risk of different chronic diseases and metabolic conditions. There is not enough evidence that choosing foods with low GI will decrease the risk of chronic diseases in the population overall.”

What are the benefits of a high fiber diet?

Normalizing Bowel movements
Maintaining Bowel Health
Lowering Cholesterol levels
Reducing High Blood Pressure
Managing Blood Sugars
Reducing Inflammation
Attaining and Sustaining an Optimal Weight
Disease Prevention
Health Promotion
Longevity

Since high fiber foods usually have a low glycemic index, why use a complicated and potentially inaccurate complex calculation when you can simply and easily focus on the fiber content of food.

How does processing affect glycemic index?

Food processing is defined as all methods and techniques used by the food, drink, and associated industries to turn whole fresh foods into food products.

Unprocessed foods are any type of food found in its natural state that has not been altered. Fresh fruits and vegetables are perfect examples of unprocessed foods. Some foods are processed more than others. Typically, the longer the ingredient list is and the more unfamiliar the ingredients are, the more processing was involved to make the food. Essentially, a processed food is just anything that’s been deliberately altered in some way before you eat it.

Low glycemic index foods are often less processed and higher in fiber.

Higher glycemic foods are more processed and lower in fiber (the grain-refining process removes the outer coat/bran from the grain, which lowers its fiber content). 

Foods that are close to how they’re found in nature tend to have a lower glycemic index than refined and processed foods.  

Conclusion:

The Problem with the glycemic index:  

• Only specifies the rate of absorption when consumed alone.
• The number can change. It is a starting point on paper. It could be different on your plate.
• Fat, fiber, and acid (such as lemon juice or vinegar) lower the glycemic index.
• The longer you cook starches like pasta, the higher their glycemic index will be.
• Does not account for ripeness (e.g., bananas glycemic index increases as they ripen).
• Does not provide any nutrient or health related information.

As a registered dietitian nutritionist, I utilize medical nutrition therapy when working with patients. The clear and simple answer to the question, “IS THE GLYCEMIC INDEX IMPORTANT IN 2024?  Or is it Outdated?” is no, don’t use the glycemic index. The glycemic index is difficult to calculate, the number changes because of many variables, including what other foods one is eating simultaneously, and is an unneeded layer of complexity when choosing what to eat.

What to do instead of using the glycemic index?

Establish a high fiber diet with a focus on whole foods. Select primary minimally processed foods, limiting the intake of high-processed foods. Establish a WHOLE FOOD, PLANT BASED, FLEXITARIAN PLAN.

Resources:

National Library of Medicine, Glycemic Index (GI) or Glycemic Load (GL) and Dietary Interventions for Optimizing Postprandial Hyperglycemia in Patients with T2 Diabetes: A Review

WebMD, How to Use the Glycemic Index

OSU, Linus Pauling Institute, Glycemic Index and Glycemic Load

National Library of Medicine, The Effects of Soluble Dietary Fibers on Glycemic Response: An Overview and Futures Perspectives