You may have seen "low GI" on food labels, diet charts and doctor's advice. But what does it actually mean, and how can you use it in everyday meals without making food complicated? This simple guide explains the glycaemic index in plain language.
What is the glycaemic index?
The Glycaemic Index (GI) is a scale from 0 to 100 that shows how quickly a carbohydrate-containing food raises blood sugar compared with pure glucose. A food that is digested and absorbed slowly has a lower GI. A food that is digested quickly has a higher GI.
The three GI bands
- Low GI: 55 or less
- Medium GI: 56 to 69
- High GI: 70 or more
Lower-GI foods release energy more gradually, which many people find helps them feel satisfied for longer.
It is not only what you eat, but how you cook it and what you eat it with.
GI is not the whole story: meet glycaemic load
GI tells you how fast a carbohydrate is absorbed, but not how much carbohydrate you actually eat. Glycaemic load (GL) considers both the GI and the portion size. This is why portion size still matters even with lower-GI foods.
What affects the GI of a food?
- Variety. Different varieties of potato, rice or sweet potato can digest at different speeds.
- Cooking method. Boiling or steaming generally results in a gentler effect than frying or very fine mashing.
- Cooling and reheating. Cooling some starchy foods may increase resistant starch, which digests more slowly.
- Fibre, protein and fat. Eating carbohydrates together with protein, vegetables and healthy fats slows digestion.
- Ripeness and processing. More processed or very soft foods usually digest faster.
Common myths
"Low GI means healthy."
Not always. Some low-GI foods can be high in fat or salt. Look at the whole food, not just the number.
"I must avoid all carbs."
Carbohydrates are an important source of energy. For most people, the goal is better-quality carbs in sensible portions, not zero carbs.
Easy ways to use GI at home
- Swap some everyday white rice for a lower-GI aromatic rice.
- Keep the skin on potatoes and sweet potatoes for extra fibre.
- Always add a vegetable and a protein to starchy meals.
- Choose steaming, boiling or roasting over deep frying.
This article is for general information and is not medical advice. If you have diabetes or any health condition, please talk to your doctor or dietitian about the right diet for you.
