Article📅 04/23/2026⏱ 10 min read🤖 AI Research

Glycemic index: food chart and 5 rules for using it

The glycemic index (GI) concept was born in 1981 at the University of Toronto as a tool for diabetics. Today everyone uses it — from people losing weight to athletes. But 80% of people apply GI wrong: they look only at the index and forget about portion size. Let's break down how GI actually works, what glycemic load (GL) is, and why watermelon at GI 75 is less "dangerous" than a baguette at GI 72.

What the glycemic index is and where it came from

The glycemic index is a number from 0 to 100 that shows how quickly a food's carbs raise blood glucose, relative to pure glucose (GI 100) or white bread (depending on the scale). The concept was developed by Professor David Jenkins at the University of Toronto to improve blood sugar control in diabetics.

The GI scale:

• Low GI: ≤55 — glucose rises slowly and gradually
• Medium GI: 56–69 — moderate rise
• High GI: ≥70 — sharp glucose spike

The idea is simple: low-GI foods = longer satiety + fewer insulin spikes + lower risk of type 2 diabetes. High-GI foods deliver fast energy (great for athletes after a workout), but carry a high risk of overeating and metabolic problems with regular consumption.

Why GI alone isn't enough — you need glycemic load

The main scientific gripe with GI: it's measured at a fixed 50 g serving of carbs. But in real life, you don't eat 50 g of carbs from watermelon (that's 750 g of flesh) — you eat one slice, about 150 g, containing 12 g of carbs.

To fix this, the concept of glycemic load (GL) was introduced in 1997:

GL = (GI × carbs in the serving in grams) / 100

The GL scale:

• Low GL: ≤10 — safe in any quantity
• Medium GL: 11–19 — worth watching
• High GL: ≥20 — rare or avoid

The classic example — watermelon vs. baguette:

Food	GI	Serving	Carbs	GL
Watermelon	75 (high)	150 g (slice)	11 g	8 (low)
Baguette	72 (high)	100 g	52 g	37 (very high)

Conclusion: watermelon, with its scary GI of 75, creates 4.5 times less load than a baguette with GI 72. That's the whole point — looking only at GI is incorrect.

Chart: 50+ foods with GI and GL

Data from the international Harvard T.H. Chan School database. Servings are typical real-world portions:

Grains and bread

Food	GI	Serving	GL
White bread	75	30 g (1 slice)	11
Whole-grain bread	54	30 g	7
Baguette	72	100 g	37
Oatmeal (rolled)	55	250 g cooked	13
Instant oatmeal	79	250 g cooked	21
Sweetened muesli	66	30 g	16
White rice	73	150 g	29
Basmati rice	52	150 g	18
Brown rice	55	150 g	18
Buckwheat	54	150 g	15
Quinoa	53	150 g	13
Durum-wheat pasta (al dente)	44	180 g	20

Fruits and vegetables

Food	GI	Serving	GL
Apple	36	1 medium (150 g)	5
Pear	38	1 medium	4
Orange	43	1 medium	5
Banana (yellow)	51	1 medium	13
Banana (with brown spots)	62	1 medium	16
Watermelon	75	150 g	8
Cantaloupe	65	150 g	7
Pineapple	66	150 g	11
Grapes	56	120 g	11
Carrots, raw	16	100 g	1
Carrots, boiled	49	100 g	3
Potato, boiled	78	150 g	21
Potato, baked	85	150 g	25
Sweet potato	63	150 g	17
Pumpkin	75	80 g	3

Legumes and dairy

Food	GI	Serving	GL
Kidney beans	24	150 g	7
Lentils	32	150 g	5
Chickpeas	28	150 g	8
Whole milk	31	250 ml	4
Plain yogurt	14	200 g	1
Ice cream	57	50 g	6

Sweets and snacks

Food	GI	Serving	GL
Cola	63	250 ml	17
Milk chocolate	43	50 g	12
Dark chocolate (70%+)	22	50 g	4
Honey	61	25 g (1 tbsp)	12
Table sugar	65	10 g (2 tsp)	6
Potato chips	54	30 g	8
Popcorn	65	20 g	7

Myth: "For weight loss you must only eat low-GI foods"

This is a popular diet built on a false premise. Yes, low-GI foods keep you full longer, which helps you eat fewer calories. But the law of thermodynamics is still in effect: if you eat more calories than you burn, you'll gain weight regardless of GI.

A 2007 Cochrane Review (Thomas et al.) of 6 studies with 202 participants found that low-GI diets were more effective for weight loss by 1 kg over 8–26 weeks. There's an effect, but it's modest. The main thing in any diet is the calorie deficit; GI is a supporting tool.

5 rules for applying GI correctly

Rule 1: Look at GL, not just GI

Watermelon and pumpkin with high GI are not a problem because their GL is low. Rice and potatoes with high GI and high GL are a real reason to limit portions. That's the core principle: GI × portion = real-world effect.

Rule 2: Cooking method changes GI

The same foods have different GIs depending on how they're prepared:

• Pasta al dente (44) vs. overcooked (61)
• Boiled potato (78) vs. baked (85) vs. cooled and reheated (60 — thanks to resistant starch)
• Slow-cooked oatmeal (55) vs. instant (79)
• Yellow banana (51) vs. spotted banana (62)

In practice: chill cooked rice or potatoes before eating — GI drops 15–20%.

Rule 3: Combine carbs with protein, fat, and fiber

Protein and fat slow carbohydrate absorption. Adding 10 g of fat or 15 g of protein to a meal cuts the peak glucose spike by 20–40% (Anderson et al., AJCN 2015).

Examples:

• White rice + chicken + avocado = real GI ~50, not 73
• Bread with butter and an egg = GI noticeably lower than bread alone
• Fruit with nuts or cottage cheese = a gradual glucose rise

Rule 4: Use GI for timing

For athletes: high GI is helpful after training (rapid glycogen replenishment). Before training and on regular days, low GI provides steadier energy.

• Before training (1–2 hours out): oatmeal, buckwheat, whole grains
• After training: rice, banana, sweets (only in the 30–60 min post-workout window)
• At night: low-GI foods — fewer glucose swings during sleep

Rule 5: For diabetes, GL is critical

If you have type 2 diabetes or prediabetes, GL is one of the best tools for glucose control. The American Diabetes Association recommends keeping total daily GL below 100. That's achievable when you:

• White rice → brown rice/buckwheat (GL 29 → 15)
• White bread → whole-grain (11 → 7)
• Fruit juice → whole fruit (15 → 5)
• Instant oatmeal → regular oatmeal (21 → 13)

When GI doesn't apply

Situations where the GI concept loses meaning:

• Pure protein and fat. Meat, fish, eggs, and nuts have a GI close to 0 or undefined — the concept doesn't apply.
• Mixed dishes. Borscht or pilaf contain so many different ingredients that GI can't be calculated — only measured with a glucometer.
• Fruit and vegetables as a base. Most have low GL regardless of GI. Don't overthink it.
• Small amounts of sweets. 30 g of chocolate or 20 g of ice cream = GL ≤6, not a problem.

Practical plan: applying GI without obsessing

1. Build your daily staples around low-GL foods: brown rice/buckwheat instead of white rice, whole-grain bread instead of white, whole fruit instead of juice.
2. Don't completely cut high-GI foods — control portions. A slice of watermelon or a banana is not a problem.
3. Add protein and fat to carbs — this lowers the real glycemic effect without forcing you to memorize numbers.
4. Watch your cooking method — pasta al dente, chill potatoes before eating.
5. Don't get fixated on numbers — total calories and overall food quality matter more than a perfect GI score.

Bottom line: what to do right now

• Swap one high-GL food in your day for a low-GL alternative (white rice → buckwheat)
• Always pair carbs with a protein and/or fat source
• Eat fruit whole, not as juice
• Chill cooked rice and potatoes — resistant starch lowers GI
• For diabetes: aim for daily GL ≤100, with low-GI foods as the foundation of your diet
• Don't fixate on individual "bad" foods — context matters more