Endocrinology & Diabetes

Glycemic Index: What's It For? How to Find Food GI?

Author Bowtie Team

Updated on 2025-08-22

Disclaimer: This article is translated with the assistance of AI.

Low Glycemic Index (GI) diets are increasingly popular, helping manage blood sugar and reduce cardiovascular disease risk. What exactly is GI? Does it impact health? What are low GI foods? Let’s find out with the Bowtie team!

What is Glycemic Index?

Glycemic Index (GI) is a measure of how foods containing carbohydrates affect your blood sugar levels.

Carbohydrates are converted into glucose during digestion and released into the bloodstream, causing blood sugar to rise. However, the extent of this rise varies depending on the type of carbohydrate, fiber content, and other factors. Simply put, high GI foods are digested more easily, leading to a faster and greater increase in blood sugar. Conversely, low GI foods are converted more slowly, resulting in a slower and smaller rise in blood sugar.

What is GI used for?

Glycemic Index is particularly important for the dietary management of diabetes patients or individuals with high blood sugar . By understanding how GI works, controlling food portions, and choosing foods with appropriate GI values and cooking methods, blood sugar levels can be managed effectively. This significantly reduces the burden on the pancreas and helps improve related conditions.

According to the guidelines from the Hong Kong Diabetes United , food GI values can be categorized into three levels: low, medium, and high. The higher the GI value, the greater its impact on blood sugar rise.

Low GI: ≤55
Medium GI: 56 – 69
High GI: ≥70

Benefits of a Low GI Diet

Reduces insulin secretion, halving the risk of diabetes complications.
Stabilizes blood sugar and lowers triglycerides, reducing the risk of cardiovascular disease.
Promotes a feeling of fullness, aiding in weight management and weight loss.

How to Effectively Control Diabetes with Glycemic Index?

Adopting a low GI diet slows down glucose conversion, reducing blood sugar spikes and thus more effectively controlling blood sugar levels. This also lowers the risk of diabetes complications. The American Diabetes Association also highlighted the benefits of a low GI diet for diabetes in 2008.

Who Benefits from a Low GI Diet?

Diabetic Patients

This group is highly suited for a low GI diet. However, it’s important to pay attention to portion control and carbohydrate counting. A balanced diet with regular meals and smaller, more frequent eating is recommended.

Individuals with PCOS

Women with Polycystic Ovary Syndrome (PCOS) are five times more likely to develop diabetes than the general population. Therefore, it’s recommended to start a low GI diet at a younger age to manage blood sugar and reduce the risk of gestational diabetes, which can increase the risk of premature birth.

Endurance Athletes

For athletes like marathon runners or climbers, consuming low GI foods before exercise can effectively improve fat-burning efficiency.

How to Estimate Food’s Glycemic Index?

Carbohydrate Content

The higher the carbohydrate content in a food, the higher its GI value. Comparing sugar and fructose, both carbohydrates, sugar is composed of two glucose molecules, making its GI value approximately three times that of fructose.

Fiber, Fat, and Protein Content

Fiber, fat, and protein all require time to digest. Therefore, they have an inverse relationship with the GI value. The higher the content of these three components in a food, the lower its GI value. This means they have less impact on blood sugar spikes in the short term after consumption.

Cooking Time, Processing, and Ripeness

Longer cooking times result in higher GI values. For example, rice cooked for 5 minutes will have a higher GI than rice cooked for only 1 minute. Additionally, smaller particle sizes or greater ripeness of food also lead to higher GI values. For instance, wheat flour has a higher GI than whole wheat, and a ripe banana has a higher GI than an unripe banana.

Common Food Glycemic Index Chart

Here’s a table of common foods and their glycemic index (GI) values, categorized by high, medium, and low GI, as well as food type:

Low GI (≤55)

Medium GI (56 – 69)

High GI (≥70)

Brown rice, black rice
Vermicelli, spaghetti, macaroni, whole egg noodles
Rye bread (Pumpernickel)
Corn, konjac
Fructose, lactose, sugar alcohols
Oranges, apples, pears, grapes, kiwis, pomelos, strawberries
Soybeans, mung beans, kidney beans, pinto beans, lentils
Skim milk, low-fat milk

Red rice, brown rice
Udon
Pita bread, croissants
Sweet potato, baked potato with skin
Sucrose, honey
Melons, bananas
Papaya, mango
Baked beans

Glutinous rice, white rice
Wheat noodles
White bread, steamed buns
Mashed potatoes, pumpkin
Glucose, sugar, maltose
Watermelon, lychee, longan

Low GI Diet Tips

Avoid Overeating

A low GI value doesn’t mean the food is low in cholesterol or calories. Some high-fat foods also have a low GI value. If you blindly overeat because of the low GI value, it might put a strain on your body.

Mind Your Cooking Methods

The shorter the cooking time, the lower the GI value. Additionally, methods like boiling, steaming, and poaching can help lower the GI value. It’s best to avoid deep-frying and thickening with starch.

Balanced Nutrition

Don’t make low GI value your sole dietary indicator. Ensure you consume other nutrients and vitamins to avoid nutritional imbalance.

Glycemic Index FAQs

Does a Low GI Diet Help with Weight Loss?

Low GI foods slow down the rise in blood sugar levels, which in turn prolongs the feeling of fullness and helps control appetite. However, not all low GI foods are healthy. Avoid high-fat options, otherwise, it will be difficult to achieve weight loss.

How is the Glycemic Index Calculated?

The glycemic index refers to the percentage of the blood sugar response level within 2 hours after consuming 50 grams of carbohydrates compared to 50 grams of glucose. The calculation is as follows:

Glycemic Index = (Area Under the Blood Glucose Response Curve 2 Hours After Consuming 50g Carbohydrates / Area Under the Blood Glucose Response Curve 2 Hours After Consuming 50g Glucose) × 100

Sources

Author

Bowtie Team

The Bowtie Life Insurance Company Limited is an authorized life insurance company and Hong Kong’s very first virtual insurer approved. Through the use of modern technology and medical expertise, Bowtie offers an agent-free, commission-free and more convenient online platform for customers to quote, apply and claim for Voluntary Health Insurance Scheme (VHIS) anytime anywhere. Bowtie is ranked first in the direct channel sales throughout 2021. Stay up to date at www.bowtie.com.hk