What is Glycemic Index & Glycemic Load?
A complete guide to understanding how different foods affect your blood sugar — and how to use this knowledge to eat smarter.
In This Guide
What is Glycemic Index (GI)?
The Glycemic Index (GI) is a number from 0 to 100 that measures how quickly a food raises your blood sugar (blood glucose) after eating it. It compares foods against pure glucose, which has a GI of 100.
Simple way to think about it: A food with GI 70 raises your blood sugar 70% as fast as pure glucose. A food with GI 30 raises it only 30% as fast — meaning a slower, more gradual rise.
Foods with a low GI are digested and absorbed more slowly, producing a gradual rise in blood sugar. Foods with a high GI are rapidly digested, causing a sharp spike followed by a crash — which can leave you feeling hungry again quickly.
The GI Scale: Low, Medium, and High
Slow, steady glucose rise. Best choice for daily meals. Keeps you full longer and helps maintain stable energy.
Examples: Most dals, brown rice, ragi, guava, curd, paneer
Moderate glucose rise. Acceptable in moderation, especially when paired with protein, fat, or fiber to slow absorption.
Examples: Basmati rice, chapati, banana, idli, poha
Rapid blood sugar spike. Limit consumption. Can cause energy crashes and increased hunger. Risky for diabetics.
Examples: White rice, naan, samosa, jalebi, white bread
What is Glycemic Load (GL)?
The Glycemic Load (GL) takes GI one step further by also considering how much carbohydrateis in a typical serving of the food. This makes it a more practical and accurate measure of a food's real-world impact on blood sugar.
The formula:
GL = (GI × grams of carbohydrate per serving) ÷ 100
GI vs GL — Why GL Matters More
GI alone can be misleading. The classic example is watermelon:
Watermelon has a high GI because the small amount of carbohydrate it contains is absorbed quickly. But a typical serving is mostly water and contains very few carbs — so the actual blood sugar impact is minimal.
This is why we show both GI and GL for every food on GlycemicIndia. GI tells you the speed of the sugar spike, GL tells you the actual magnitude. For practical diet decisions, GL is usually the better number to watch.
What Affects a Food's GI?
The GI of a food is not fixed — several factors can raise or lower it:
1. Cooking Method
Longer cooking breaks down starches, increasing GI. Al dente pasta has lower GI than overcooked pasta. Similarly, pressure-cooked rice has higher GI than normally boiled rice.
2. Processing & Refining
Removing bran and fiber (like polishing rice or refining wheat into maida) dramatically increases GI. This is why brown rice has lower GI than white rice, and atta is better than maida.
3. Fiber Content
Fiber slows digestion and glucose absorption. Foods naturally high in fiber (dals, millets, vegetables) tend to have lower GI. Adding vegetables to any dish lowers the overall GI of the meal.
4. Fat & Protein Content
Fat and protein slow stomach emptying, which slows glucose absorption. This is why adding curd to rice, or eating dal with chapati, results in a lower glycemic response than eating the carbohydrate alone.
5. Ripeness (Fruits)
As fruits ripen, their starches convert to sugars, increasing GI. A green banana has significantly lower GI than a fully ripe one with brown spots.
6. Cooling (Resistant Starch)
Cooking and then cooling starchy foods (rice, potatoes) creates resistant starch, which acts like fiber and lowers GI. Cold rice in curd (dahi chawal) has lower GI than freshly cooked hot rice.
7. Fermentation
Fermented foods like idli, dosa batter, and curd undergo bacterial breakdown of sugars, which can slightly reduce GI and improve nutrient absorption.
8. Acidity
Adding acidic ingredients like lemon juice, vinegar, tamarind, or amchur (dry mango powder) to a meal can lower the glycemic response by slowing gastric emptying.
GI in the Indian Context
The Indian diet is heavily carbohydrate-based — rice, wheat, and millets form the foundation of most meals. This makes understanding GI especially important for Indians, who have one of the highest rates of diabetes in the world.
The Good News
- • Indian dals and legumes are among the lowest GI foods globally
- • Traditional millets (ragi, bajra, jowar, foxtail) are excellent low-GI grains
- • Spices like fenugreek, cinnamon, and turmeric may help with blood sugar regulation
- • The Indian tradition of eating curd with meals naturally lowers glycemic response
- • Fermented foods (idli, dosa, dahi) are part of daily diet
The Challenge
- • Polished white rice (GI 73) is consumed in large quantities, especially in South India
- • Maida (refined flour) is used in naan, samosa, bread, biscuits, and bakery items
- • Sugar and jaggery consumption in sweets, chai, and beverages is high
- • Portion sizes of rice and roti tend to be large, increasing total glycemic load
- • Deep-fried snacks (samosa, pakora, vada) are calorie-dense
Practical Tips to Lower Your Meal's GI
Swap white rice for brown rice, millets, or hand-pounded rice
Can reduce meal GI by 15-25 points
Always include dal or legumes with your meals
Dals have GI as low as 8-31, bringing down overall meal GI
Add curd or buttermilk to your meal
Protein and fat in dairy slow glucose absorption
Load up on non-starchy vegetables
Fiber from vegetables slows digestion and reduces GL
Cool your rice before eating (or eat leftover rice)
Cooling creates resistant starch, reducing effective GI by up to 25%
Choose whole wheat atta over maida
Whole wheat has 25-30% lower GI than refined flour
Add lemon juice or vinegar to meals
Acidity slows gastric emptying and glucose absorption
Eat fruit whole, not as juice
Juicing removes fiber and concentrates sugars, spiking GI dramatically
Start meals with protein or vegetables before carbs
Eating order affects glucose response — carbs last is better
Walk for 10-15 minutes after meals
Post-meal walking helps muscles absorb glucose, reducing blood sugar spikes
Limitations of GI
While GI is a useful tool, it has limitations you should be aware of:
- Individual variation: Two people eating the same food can have very different blood sugar responses based on their insulin sensitivity, gut microbiome, genetics, and activity level.
- Mixed meals: GI is measured for individual foods eaten in isolation. In reality, we eat mixed meals where proteins, fats, and fiber all modify the glycemic response.
- Doesn't measure insulin response: Some foods cause high insulin release despite low GI (like dairy products).
- Doesn't account for nutrition: A food can be low GI but still unhealthy (e.g., high in saturated fat or empty calories). GI is one factor, not the only factor.
- Testing variations: GI values can differ between studies due to different testing methods, food varieties, and preparation techniques.
Bottom line: Use GI and GL as helpful guides, not rigid rules. The best approach combines GI awareness with overall balanced eating — plenty of vegetables, adequate protein, healthy fats, and moderate portions of carbohydrates. And always work with your healthcare provider for personalized advice.
Ready to Explore?
Now that you understand GI and GL, browse our database of Indian foods or try the meal calculator.