Glycemic Index and Glycemic Load Calculator

The glycemic index (GI) measures how quickly a food raises blood glucose compared to pure glucose (GI=100), based on a 50 g carbohydrate portion. Foods with low GI (<55) cause a gradual rise in blood sugar, while high GI foods (≥70) cause a rapid spike.

Glycemic load accounts for both the GI of a food and the actual amount of carbohydrates in the portion eaten. Formula: GL = (GI × carbs in portion) / 100. It better reflects the real impact of a meal on blood glucose than GI alone.

GI classification: low GI < 55 (e.g. most vegetables, legumes, wholegrain bread), medium GI 55–69 (e.g. white rice, bananas), high GI ≥ 70 (e.g. white bread, boiled potatoes, sugary drinks). A low-GI diet helps stabilise blood glucose levels.

GL per portion: low GL < 10, medium GL 10–19, high GL ≥ 20. Daily dietary GL: low < 80, medium 80–119, high ≥ 120. High-GI foods can have low GL in small portions (e.g. watermelon: GI=72, but GL ≈ 4 for a 120 g portion).

GI measures carbohydrate quality but not quantity. Watermelon has a high GI (72) but low carbohydrate content, giving it a low GL. Glycemic load combines both pieces of information — providing a better picture of a portion's actual impact on glycaemia, especially important for diabetics and those on low-carb diets.

GI and GL control is most important for: people with type 2 diabetes and insulin resistance, those with metabolic syndrome, women with gestational diabetes, people trying to lose weight, and athletes timing meals around training sessions.

Low GI (<55) foods include: most vegetables (especially leafy greens), legumes (lentils GI=29, chickpeas GI=28), berries, cherries, apples, nuts, whole grains, brown rice, plain yoghurt. Cooking al dente and combining with fat or protein lowers a meal's GI.

Cooking, baking and processing generally raise GI — starch gelatinises and becomes more accessible to digestive enzymes. Al dente pasta has a lower GI than overcooked pasta. Cooling cooked potatoes or rice (then reheating) lowers GI by forming resistant starch. Grinding or pureeing foods usually increases GI.

Research suggests that a low-GI diet may aid weight loss through greater satiety, smaller insulin spikes and reduced hunger. However, total caloric balance is still the key factor. A low-GI diet also supports better metabolic health and blood sugar regulation.

The calculator uses the formula: GL = (GI × carbs in portion) / 100, where carbs in portion = (serving_g / 100) × carbs_per_100g. It then classifies the product's GI (low <55, medium 55–69, high ≥70) and the portion's GL (low <10, medium 10–19, high ≥20).