Are glycemic index charts a good way to understand your responses to food?

A glycemic index chart shows how the carbohydrates in food can affect your blood sugar. Foods are assigned a value between 0 and 100, based on how quickly they cause blood sugar levels to rise. The higher the number, the faster your blood sugar goes up.

Foods on the low end of this range, such as many beans and fruits, are digested slowly and cause blood sugar levels to rise gradually. 

Those with a high glycemic index (GI) are quickly digested and absorbed, leading to larger spikes in blood sugar.

Glucose, a simple sugar, tops the list with a glycemic index of 100. But refined grains such as white bread fall into the high GI category, as do processed foods — like sodas, snack foods, and many breakfast cereals. 

In general, whole grains such as oatmeal and whole-grain pasta have a medium glycemic index, leading to moderate rises in blood sugar.

However, the scores you’ll see on a glycemic index chart are not the whole picture when it comes to your personal responses to food.

ZOE runs the largest nutritional study of its kind, and ZOE scientific advisory board member Jennie Brand-Miller — Professor of Human Nutrition at the University of Sydney — is a world leader when it comes to studying glycemic index. 

ZOE’s research has shown that different people’s blood sugar responses to the same foods can vary significantly. There are also a number of other factors involved in how your body processes food. 

The ZOE at-home test analyzes not only your individual blood sugar and blood fat responses to what you eat, but also the trillions of microorganisms in your unique gut microbiome, which impact how you metabolize food.

The ZOE program gives you personalized scores for hundreds of foods and suggests different food combinations, which can also change your body’s responses. 

You can find out more by taking a free quiz.

Glycemic index charts

A glycemic index chart ranks common foods based on their glycemic index values and groups them as low, medium, or high glycemic foods. 

Foods with a glycemic index of 55 or less are considered low glycemic foods, foods rated 56–69 are in the medium range, and those with a glycemic index of 70–100 are considered high glycemic foods.

You can see examples of approximate scores for common foods in the glycemic index charts below.

However, the scores may vary between different products and cooking methods. You can check some specific products here.

Low glycemic index chart

Foods that fall into the low glycemic index category include:

FoodGlycemic index
bananas 51
black beans31
bran cereal51
kidney beans36
milk (full-fat)30
oranges (navel)45
pinto beans45
yogurt (no added sugar)21

Medium glycemic index chart

Foods with a medium glycemic index score include:

FoodGlycemic index
cane sugar (sucrose)60
crackers (wheat)60
whole wheat pasta59

High glycemic index chart

Common foods with high glycemic index values include:

FoodGlycemic index
baguette bread83
cheese puff snacks70
cornflakes (breakfast cereal)80
potatoes (white)72
potato chips71
rice, white jasmine82
sweet potatoes71
white bread81

Why blood sugar responses are important

Increases in your blood sugar after you eat can be followed by dips.

Small changes in blood sugar are a normal part of how your body responds to food, but larger spikes and “crashes” can be a problem. 

In the short term, blood sugar crashes can leave you feeling tired or low in energy. ZOE’s research has also shown that they can make you hungrier and lead to you eating more.   

But over time, these large changes have more serious health implications. If you regularly experience blood sugar spikes and crashes, it can increase your risk of chronic inflammation and metabolic illnesses like heart disease, stroke, and type 2 diabetes.

There’s more to your food responses than the GI

Glycemic index values for foods don’t apply equally to everyone. 

While they may give you a broad idea of what could happen to your blood sugar when you eat certain things, they don’t take into account the differences between individuals or other factors that affect how your body responds to food. 

Research has shown that glycemic responses to the same foods can vary significantly between people. 

For example, in one study, there was as much as a 25% difference between how the participants’ blood sugar levels changed after eating white bread.

And ZOE data have shown similar variations between people. Below, you can see the difference between a moderate and high blood sugar response when two different people ate a banana.

What’s more, glycemic index scores only account for what happens when you eat a particular food by itself. They don’t look at how foods interact to affect your blood sugar when they’re eaten together in a meal.

And, of course, glycemic index values are only related to changes in your blood sugar levels, not your body’s other important responses to food.   

At ZOE, we run the largest nutrition study in the world, with over 15,000 participants so far. Our data have shown that everyone responds differently to foods.

Your blood sugar responses are only one aspect linking how your body processes foods to your overall health. Our research shows that your blood fat responses and the makeup of your gut microbiome also play important roles.

The ZOE at-home test can tell you how different foods impact your blood sugar and blood fat, as well as your gut health. Based on your unique results, the ZOE program then gives you personalized scores for hundreds of foods and shows you how they work in combination for your body.

You might be surprised at your recommendations. Just because a food has a higher glycemic index value, doesn’t automatically mean it’s not good for you.

Take a free quiz to learn how ZOE can help you.


Glycemic index charts can give you a broad idea of how a particular food might affect your blood sugar. 

Each food has a score between 0 and 100, based on how fast it causes blood sugar levels to rise, on average. Based on this score, it’s either in the low, medium, or high glycemic foods group.

Lower glycemic foods generally lead to more gradual rises in blood sugar, while high glycemic foods can cause levels to spike and then crash. If these crashes happen regularly, they can increase your risk of illnesses like heart disease and type 2 diabetes.

However, the glycemic index scores of individual foods can depend on particular brands and cooking methods. And glycemic index scores don’t take into account how combinations of foods affect each other when you eat them together.

Perhaps most importantly, glycemic responses to specific foods also vary significantly between people.

At ZOE, we know that everyone responds to foods differently and that your blood sugar is only one part of the picture.

Our at-home test kit analyzes your blood sugar and blood fat responses, along with your gut health, to help you choose the foods that are best for you.

You can take a free quiz to find out what’s possible with ZOE.


Carbohydrates and blood sugar. (n.d.).

Estimating the reliability of glycemic index values and potential sources of methodological and biological variability. The American Journal of Clinical Nutrition. (2016). 

Evaluation of the effect of macronutrients combination on blood sugar levels in healthy individuals. Iranian Journal of Public Health. (2021).

GI search. (n.d.)

Postprandial glycaemic dips predict appetite and energy intake in healthy individuals. Nature Metabolism. (2021). 

What is glycemic index? (2019).