Understanding the difference between low carb and low GI 

By Rebecca McPhee, Accredited Practising Dietitian

How often do your clients ask, “what is the different between low carb and low GI?” or “Is low carb and low GI the same?” Here is a simple way to explain the two concepts, that are not the same but interrelated.  

Low carb: Low carbohydrate (low carb) and low Glycemic Index (low GI) are linked but different. Low carb refers to the quantity of carbohydrate which means that a low carb food/meal/beverage does not contain much carbohydrate. A low carbohydrate diet or low carb food/meal/beverage will usually include more fat and/or protein.  

Low GI: Low GI on the other hand refers to the quality of carbohydrates and the speed in which it digests in the body. Low GI foods provide many health benefits, including improved blood glucose. 

How do they relate to diabetes? 

When we eat carbs, they break down to form glucose (sugar) in the blood. Your pancreas then takes this glucose to your cells for energy. Reducing the amount of carb you eat (quantity) means that there will be less breakdown of glucose in the blood and less use of insulin. Whilst carbs are an important energy source and fuel for our brain and muscles to function well, if we eat a large amount of carbs, our body must produce more insulin. This can be problematic for people with type 2 diabetes because the insulin is already not working efficiently so we want to preserve it as much as possible and not wear out the pancreas. Reducing carbohydrates to reduce glucose to reduce insulin production is an effective strategy for diabetes control.  

However, there is no one size fits all diet for diabetes. Not everyone will need to follow a low carbohydrate diet so the amount of carbohydrate a person with diabetes needs each day will vary.  With type 1 diabetes for example, the dosage of insulin is matched to the amount of carbohydrate eaten. 

Low GI is all about choosing quality carbs that will benefit our blood glucose levels. Low GI carbs break down to form glucose in your blood at a slower rate, so they are the preferred choice for diabetes and weight loss. Think high fibre, whole foods that take longer to chew, longer to digest and longer to fill you up. For example, swapping processed, white bread to wholegrain or authentic sourdough bread or quick cooking oats for steel cut, whole oats. Low GI foods are often more filling so you will find that you need less which can also assist with weight management.  

Being carb smart 

Including smaller, low GI carb portions (combining quality carbs in the right quantity) is all about being ‘carb smart’. Testing your blood glucose two hours after a meal is a great way to figure out if the type and amount of carbs suit you. This may mean that you do not need to follow a low carb diet but just exercise caution with carb portions i.e., portion caution!  

Carb smart examples: 

• Swap 2 slices white toast for 1 slice low GI, wholegrain toast. Spread toast with ¼ avocado, add 2 eggs and sauteed veggies e.g., tomato, spinach, and mushrooms. Add a squeeze of fresh lemon and black pepper. 
• Swap white rice for low GI, basmati brown rice. Reduce portion from one cup cooked to ½ cup cooked. Add more veggies to your meal and a serve of lean protein.  
• Swap 2 white potatoes for 1 Carisma lower GI potato. Add extra veggies to your plate and a serve of lean protein.