Glycemic Index (GI) Food Checker
Search 80+ foods to find their glycemic index. Discover which foods raise blood sugar quickly and which keep it stable — essential for diabetes, pre-diabetes, weight management, and sustained energy.
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What Is the Glycemic Index?
The glycemic index (GI) measures how quickly a carbohydrate-containing food raises blood glucose compared to pure glucose. Pure glucose scores 100. A food with a GI of 50 raises blood sugar about half as fast. Foods are tested on real people — participants fast overnight, eat a measured portion of the test food, then have blood glucose measured every 15–30 minutes for 2 hours.
GI is useful but has important limitations. A small slice of watermelon has a high GI (72) but the actual amount of carbohydrate in a typical serving is small — so its real blood sugar impact (glycaemic load, or GL) is low. GI also doesn't account for how different people respond to the same food, or how combining foods in a meal affects absorption.
GI vs Glycaemic Load — Key Difference
| Category | What it measures | What it misses | Best used for |
|---|---|---|---|
| Glycemic Index | How fast blood sugar rises per gram of carbohydrate | How much carbohydrate is actually in a serving | Comparing carbohydrate quality between foods |
| Glycemic Load | GI × grams of carb / 100 | Individual metabolic variation | Estimating real-world blood sugar impact of a serving |
Why GI Matters — Health Implications
Chronic high blood sugar and repeated insulin spikes are linked to type 2 diabetes, cardiovascular disease, weight gain, and energy crashes. A diet built around low-GI foods keeps blood sugar and insulin levels more stable — leading to sustained energy, better appetite control, and lower metabolic risk over time. Large studies including the EPIC study and Nurses' Health Study consistently find associations between high-GI diets and chronic disease risk.
Factors That Change a Food's GI
| Factor | Effect on GI | Example |
|---|---|---|
| Cooking method | Longer/higher heat raises GI | Baked potato (GI 80) vs boiled potato (GI 59) |
| Food processing | More processing raises GI | Instant oats (GI 79) vs rolled oats (GI 55) |
| Ripeness | Riper = higher GI | Ripe banana (GI 62) vs unripe (GI 42) |
| Cooling after cooking | Resistant starch formation lowers GI | Cold potato (GI 35) vs hot (GI 59) |
| Combining with fat/protein | Slows digestion, lowers GI | Rice + beans together is lower GI than rice alone |
| Fibre content | Higher fibre = lower GI | Rye bread (GI 41) vs white bread (GI 70) |
| Acidity | Vinegar/lemon lower GI | Adding vinegar to a meal can meaningfully lower GI |
🍽️ Practical tip: You don't need to avoid high-GI foods entirely — combining them with protein, fat, or fibre at the same meal significantly slows absorption. A baked potato eaten alone spikes blood sugar fast. The same potato eaten with butter, sour cream, and a side salad raises it much more slowly.
Frequently Asked Questions
Is GI the best way to manage blood sugar with diabetes?
GI is a useful tool but not the only one. For people with type 2 diabetes or pre-diabetes, total carbohydrate intake (carb counting) is typically the primary tool — GI helps refine which carbohydrates are better choices. Work with your diabetes care team for personalised guidance. GI alone won't tell you whether a food fits your carb target.
Why do some "healthy" foods like watermelon have a high GI?
GI can be misleading in isolation. Watermelon has a GI of 72 (high), but a typical slice contains only 7g of carbohydrate — a very small amount. Its glycaemic load (GL) is about 5, which is low. High GI + low carb content per serving = manageable impact. Conversely, white bread has a high GI AND a high carb load — making it a genuine concern.
Does the GI of a food change when you combine it with other foods?
Yes, significantly. Fat, protein, acidity (vinegar, lemon), and fibre all slow gastric emptying and reduce the glycaemic response of any meal. A piece of white bread eaten alone raises blood sugar faster than the same bread eaten as part of a meal with eggs, olive oil, and salad. Meal composition matters as much as individual food GI.
Is brown rice actually better than white rice for blood sugar?
Only modestly. Brown rice has a GI of around 64 versus 73 for white rice — a meaningful difference, but not dramatic. Both are medium-to-high GI. If blood sugar management is a priority, basmati rice (~58 GI) or even pasta are better alternatives. Cooling cooked rice (of any type) forms resistant starch and significantly lowers its GI.
What about sugar substitutes and artificial sweeteners — do they affect GI?
Most artificial sweeteners (stevia, erythritol, aspartame, sucralose) have a GI of 0 — they don't raise blood sugar directly. However, research on their effects on gut bacteria, insulin response, and appetite is ongoing and mixed. They're a tool, not a free pass. Whole food approaches are preferable where possible.
Can low-GI eating help with weight loss?
It can, particularly through appetite regulation. Low-GI foods tend to produce less insulin response, which may reduce fat storage and support longer satiety. A 2021 Cochrane review found modest but meaningful evidence that low-GI diets support weight management compared to higher-GI equivalents. The effect is stronger when total carbohydrate quality (not just GI) is improved across the whole diet.