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Glycemic Index: What It Is and How to Use It

Posted by Manuela Boyle on 10 March 2022
Glycemic Index: What It Is and How to Use It

The glycaemic index is a tool that’s often used to promote better blood sugar management.

Several factors influence the glycaemic index of a food, including its nutrient composition, cooking method, ripeness, and the amount of processing it has undergone.

The glycaemic index can not only help increase your awareness of what you’re putting on your plate, but also enhance weight loss, decrease your blood sugar levels, and reduce your cholesterol.

 The glycaemic index (GI) is a value used to measure how much specific foods increase blood sugar levels.

Foods are classified as low, medium, or high glycaemic foods and ranked on a scale of 0–100.

The lower the GI of a specific food, the less it may affect your blood sugar levels 

Here are the three GI ratings:

  • Low: 55 or less
  • Medium: 56–69
  • High: 70 or above

Foods high in refined carbs and sugar are digested more quickly and regularly have a high GI, while foods high in protein, fat, or fibre typically have a low GI. Foods that contain no carbs are not assigned a GI and include meat, fish, poultry, nuts, seeds, herbs, spices, and oils. Other factors that affect the GI of a food include the ripeness, cooking method, type of sugar it contains, and amount of processing it has undergone.

Keep in mind that the glycaemic index is different from the glycaemic load (GL).

Unlike the GI, which doesn’t take into account the amount of food eaten, the GL factors in the number of carbs in a serving of a food to determine how it may affect blood sugar levels. For this reason, it’s important to take both the glycaemic index and glycaemic load into consideration when selecting foods to help support healthy blood sugar levels.

The low glycaemic diet involves swapping out foods with a high GI for those with a lower GI.


Following a low glycaemic diet may offer several health benefits, including:

  • Improved blood sugar regulation. Many studies have found that following a low GI diet may reduce blood sugar levels  and improve blood sugar management during cancer treatments.
  • Increased weight loss. Some research shows that following a low GI diet may increase short-term weight loss. More studies are needed to determine how it affects long-term weight management.
  • Reduced cholesterol levels. Following a low GI diet may help lower levels of both total and LDL (bad) cholesterol, both of which are risk factors for heart disease.

How to follow

A healthy, low glycaemic diet should comprise mostly low GI foods, such as:

  • Fruits: apples, berries, oranges, lemons, limes, grapefruit
  • Non-starchy vegetables: broccoli, cauliflower, carrots, spinach, tomatoes
  • Whole grains: quinoa, couscous, barley, buckwheat, farro, oats
  • Legumes: lentils, black beans, chickpeas, kidney beans

Foods with a high GI include:

  • Bread: white bread, bagels, naan, pita bread
  • Rice: white rice, jasmine rice, arborio rice
  • Cereals: instant oats, breakfast cereals
  • Pasta and noodles: lasagna, spaghetti, ravioli, macaroni, fettuccine
  • Starchy vegetables: mashed potatoes, potatoes, french fries
  • Baked goods: cake, doughnuts, cookies, croissants, muffins
  • Snacks: chocolate, crackers, microwave popcorn, chips, pretzels
  • Sugar-sweetened beverages: soda, fruit juice, sports drinks


Author:Manuela Boyle
Tags:NewsResourcesPrevention & RecoveryCancerFood as Medicine


  • The Institute for Functional Medicine
  • Society for Integrative Oncology
  • Naturopaths and Herbalists Association of Australia
  • Australian Traditional-Medicine Society
  • British Naturopathic Association