Eating a low glycaemic index (GI) diet is a fantastic way to maintain overall health and prevent or reverse prediabetes and type 2 diabetes.
Wondering what a low-GI diet is?
A low-GI diet consists of slow-digesting carbohydrates that increase blood glucose levels gradually without causing insulin spikes. Low-GI carbohydrates include beans, lentils, barley, green leafy vegetables, and apples.
As you may have guessed, eating a well-balanced low-GI diet can minimise blood sugar fluctuations and increase insulin sensitivity, which improves blood glucose control and lowers the risk of type 2 diabetes. Notably, a low-GI diet with moderate-high intensity exercise can put type 2 diabetes in remission.
Slow-digesting carbohydrates are crucial for a low-GI diet but eating quality proteins, and fats are also essential to keeping the GI of your diet low. And you must also eat these foods in the correct proportions.
Before we teach you how to start eating a healthy low-GI diet, let’s cover some basics.
What is the Glycaemic Index?
The glycaemic index (GI) measures how carbohydrates affect your blood glucose levels. It ranks foods on a scale of 0 to 100, depending on how quickly they raise blood sugar levels. Foods that raise blood sugar very quickly have a high number, whereas foods that raise blood sugar slowly have a lower number.
Glucose and white bread raise blood glucose the quickest and have the highest GI rating of 100. Scientists determine the GI of other foods by comparing their effects on blood sugar with those of glucose or white bread, typically white bread.
To do this, scientists give healthy individuals 50g of white bread and then measure their blood glucose levels at regular intervals over two hours. They repeat the same experiment with the food they’re investigating, i.e., measuring blood glucose levels at regular intervals over two hours after the test food is eaten.
They then divide the blood glucose response of the test food by that of white bread and multiply by 100; the resulting figure is the GI of the food.
GI is grouped into three categories for easier interpretation. Foods with a GI of:
- 0 – 55 are low, e.g., barley, beans, leafy vegetables
- 56 – 69 are medium, e.g., white basmati rice, pasta
- 70 – 100 are high, e.g., white bread, watermelon, white, long-grain rice
A key point about the GI of a food is that it varies depending on the amount you eat and if you eat it with other foods. For example, 20g of watermelon has a lower GI than 50g, and 100g of white rice has a higher GI than 40g. Moreover, the GI value of 50g of apple and 50g of peanut butter is lower than 50g of apple.
Another vital point is that not all low GI foods are ‘healthy’ and not all high GI foods are ‘unhealthy’. For example, a snickers bar has a GI of 43, while watermelon has a GI of 72. Watermelon is clearly more nourishing than a snickers bar with its high vitamin and mineral content.
You should focus on both the quality and quantity of food you eat to get the most of the GI rating. Notably, the glycaemic load, which considers both GI and portion size, is more effective for controlling blood sugar and maintaining overall health.
GI VALUES OF COMMON CARBOHYDRATE-CONTAINING FOODS
Whole wheat / wholemeal bread
White rice, boiled
White basmati rice, boiled
Brown rice, boiled
Porridge, rolled oats
Instant oat porridge
Rice porridge / congee
|Fruit and fruit products|
Strawberry jam/ jelly
Potato, instant mashed
Potato, French fries
Sweet potato, boiled
Plantain / green banana
|Dairy products and alternatives|
Milk, full fat
|Atkinson, Foster-Powell & Brand-Miller 2008; Ranawana et al., 2009|
How to Eat a Healthy Low-GI Diet
1 | Upgrade your carbohydrate choice
Eating a low GI diet starts with choosing high-quality carbohydrates, specifically carbohydrates in their natural, unprocessed forms. These carbohydrates generally have a higher fibre content and retain most of their naturally occurring vitamins and minerals, making them more nourishing than their refined alternatives. Because of their higher fibre content, your body digests high-quality carbohydrates slowly, causing your blood sugar levels to rise gradually.
Which carbohydrates are considered high-quality?
High-quality carbohydrates include whole grains such as brown rice, pearl barley, oats, and sweet potatoes. They also include all vegetables, fruits, nuts, seeds, beans, and lentils.
The first thing you can do is swap most refined grains in your diet with whole grains. For example, you can switch white bread for whole wheat or seeded brown bread, white long-grain rice for brown, long grain rice or basmati rice (white basmati rice has a lower GI than brown rice) and sugary breakfast cereals like Frosties for all bran or bran flakes.
2 | Combine foods properly
We generally don’t eat carbohydrates alone. But if you do, please stop because it spikes your blood sugar and insulin excessively. That said, eating carbohydrates with high-quality proteins and fats is a fantastic way to lower the GI of your diet, even if you choose a high GI carbohydrate.
Proteins such as meat, poultry, and eggs have minimal effects on blood glucose and insulin levels. And although considered vegetables, beans and lentils are good protein sources that also have low GI levels. But their GI levels are not as low as meat, poultry, or eggs.
Fats are unique because they are the only macronutrient with negligible effects on blood glucose and insulin. Just pairing carbohydrates with fat lowers the GI of your meal, and adding protein further reduces it because it slows down digestion and keeps you satisfied for longer.
A good rule of thumb is to ensure you have high-quality carbohydrates, proteins, and fats on your plate always. Meals with this food combination will keep you full for longer periods and provide many vitamins, minerals, and antioxidants.
3 | Master portions
Portion size matters!
Even if you choose high-quality carbohydrates and pair them with high-quality fats and proteins, the GI of your meal can end up being high if your portion sizes are too large.
The amount of food you need varies depending on your age, height, weight, activity levels and lifestyle. A 32-year-old woman, who weighs 60kg, is 5’2” inches tall, exercises five times a week and has a very active job will have completely different requirements to a 50-year-old woman who weighs 80kg, is 5’10” inches tall, exercises once a week and have a sedentary job.
One size clearly doesn’t fit all.
And this is the reason diets with blanket suggestions for all women fail. Our registered nutritionist can determine the right portions of food for you based on your age, height, weight, exercise levels, lifestyle, and goals.
You can enquire about this service here.
4 | Plan, plan, plan
Don’t underestimate the power of planning. Planning makes your life much easier and dramatically reduces decision fatigue.
Choose your least busy day to select the snacks, meals, or recipes you’d like to eat the following week and then create a list of the ingredients you need for them. You can make life even easier by selecting frozen items (e.g., vegetables or fruit) to cut down on preparation time and batching cooking foods like stews and curries or roasting chicken and vegetables that you can reheat throughout the week.
Ensure you always have low-glycaemic convenience foods stocked. Foods like edamame, eggs, nuts, seeds, fruits and chopped vegetables, e.g., carrots, cucumbers, bell peppers and hummus, make fantastic snacks.
So, how do you start eating a healthy low-GI diet?
You first understand what GI means, then upgrade your carbohydrate choices, learn to combine food groups correctly, eat the correct portion sizes and plan.
We all know that most things are easier said than done. But don’t read without acting. Put these tips into practice at your next meal if possible
And remember, you don’t have to go big or go home. You can start small and stay consistent. Your destination is what matters.
Make 2022 your year. You can do this!
- Atkinson, F.S., Foster-Powell, K., Brand-Miller, J.C. (2008) Internation talbes of glycaemic index and glycaemic load values: 2008. Diabetes Care, 31: 2281-2283.
- Henry, C.J., Quek, R.Y.C., Kaur, B., Shyam, S * Sing, H.K.G. (2021) A glycaemic index compendium of non-western foods. Nutrition and Diabetes, 11: 2
- Ranawana, D.V., Henry, C.J.K., Lightowler, H.J., & Wang. D. (2009) Glycaemic index of some commercially available rice and rice products in Great Britain. International Journal of Food Sciences and Nutrition, 60(Supplement 4): 99-110.
- Thomas, D.E. & Elliott, E.J. (2010) The use of low-glycaemic index diets in diabetes control. British Journal of Nutrition, 104: 797-802.
- Augustin, L.S.A., Kendall, C.W.C., Jenkins, D.J.A., Willett, W.C., Astrup, A., Barclay, A.W., Bjorck, I., Brand-Miller, J.C., Brighenti, F., Buyken, A.E>, Ceriello, A., La Vecchia, C., Livesey, G., Liu, S., Riccardi, G., Rizkalla, S.W., Sievenpiper, J.L., Trichopoulou, A., Wolever, T.M.S., Baer-Sinnott, S., and Poli A. (2015) Glycaemic index, glycaemic load and glycaemic response: An international scientific consensus summit from the International Carbohydrate Quality Consortium (ICQC). Nutrition, Metabolism & Cardiovascular Diseases, 25: 795-815.