Decoding Glycemic Index of Foods

You have probably heard about eating “carbs” with low glycemic index (GI) can help with weight loss? But what are “carbs”? Carbohydrates are digested in the body and broken down into glucose - a type of sugar that provides fuel for the brain, muscles and most organs to function. Since not all carbohydrates are created equal, different types of carbohydrates in foods are broken down into glucose/sugar in different speed, resulting in different GI values. In another words, GI is used to measure the rate of carbohydrate metabolism in the body and how it affects blood glucose levels. 


Foods are assigned GI numbers based on the comparative rises in blood glucose/sugar levels they produce in the body. A high glycemic food is easy to break down into glucose when eaten, causing a quick rise and fall in blood sugar levels due to insulin secretion in response to the blood sugar increase. This can make one to feel hungry sooner, body fat accumulation and weight gain. In contrast, low to moderate glycemic foods take longer to break down into glucose, resulting in a more gradual rise in blood sugar levels, thus maintaining an increased energy level for a longer period. This also means more steady insulin secretion so that the body can maintain the stability of blood glucose and regulate hunger. 


Studies that research about dietary habits show that foods with higher GI value are a risk factor for diabetes, obesity, and cardiovascular disease. Therefore, eating a low glycemic diet not only helps to manage weight, it may also help to manage/reduce risk of developing Type II Diabetes, and lower chances of getting heart disease and some cancers. 


GI values of foods

Food categories

Low GI (55 or less)

Priority Choice

Intermediate GI (56-69)

Choose often

High GI (70 or more)

Choose less


100% stone-ground whole wheat bread

Pumpernickel bread

Whole wheat rye/ pita

Quick oats
Brown/ wild/ basmati rice


White bread/ bagel


Oatmeal (rolled or steel-cut)

Oat bran


Puffed cereal

Quick oats

Raisin Bram

Special K

Bran flakes
Corn flakes

Puffed rice

Instant oatmeal






Basmati rice


Wild rice

Rice noodles


Buckwheat noodle

Sticky rice
Short grain white rice

Macaroni and cheese from mix

Root vegetables,

Beans and lentils,

Common snacks

Sweet potato


Dried beans and lentils such as black beans, garbanzo beans, white beans



Stoned Wheat Thins™

Russet potato

Mashed potato

Saltine crackers

Rice cake


and fruits

Non starchy vegetables and carrots

Most fruits such as apples, pears, grapefruit, kiwi, grapes, strawberries.







Litchi and longan

Reference: American Diabetes Association and Canadian Diabetes Association.


By Hazel Ng, RD CDE / Dorothy Ian Chan, RD

Copyright © | Bor S. Luh Food Safety Research Center  of Shanghai Jiao Tong University 2015