The glycemic index (GI) shows how quickly the glucose level in your blood rises after you eat a food. Measurement takes place two hours after digestion, with the same amount of pure glucose, whose index is 100, used as the reference. The lower the number, the calmer the insulin response – and the longer you stay full.
What the glycemic index really is
Here’s the simple truth: GI doesn’t depend only on how many carbohydrates a food contains. What surrounds those carbohydrates matters just as much. Dietary fiber and fat slow down stomach emptying and the absorption of carbohydrates in the intestine. The result – blood sugar rises more smoothly and less insulin is released.
This is where a common misunderstanding comes from. If a treat is high in fat, its GI looks quite low. But the calories don’t vanish. A chocolate bar may give your blood sugar a gentler nudge than white bread, yet it delivers a lot of energy without any meaningful nutrients. Sweets contain essentially nothing besides sugar and fat – no vitamins, no minerals, no protein.
How the glycemic index affects body weight
High-GI foods push insulin up sharply. Insulin is a hormone that, among other things, directs glucose from the blood into the cells and stores the excess as fat. After a sharp spike, blood sugar often falls below normal and a new wave of hunger sets in – two hours after lunch you want to grab something again. That’s how calories quietly add up over the course of the day.
Low-GI foods (roughly below 55) keep your energy more even. For people who train, that means steadier performance during longer workouts and less temptation to park yourself in front of the fridge in the evening. For anyone trying to lose body weight, it offers an easier way to stay within the weekly calorie budget without putting up with constant gnawing hunger.
An important nuance: you can overeat low-GI foods too. Nuts are a great example – the index is tiny (10–19), but 100 g brings in almost 600 kcal. GI is a tool, not a permission slip.
Glycemic index chart of foods
| Food | GI | Food | GI |
|---|---|---|---|
| Glucose | 100 | Orange and orange juice | 40–49 |
| Cornflakes | 80–90 | Wheat pasta | 40–49 |
| Carrots | 80–90 | Tomatoes | 30–39 |
| Honey | 80–90 | Apples | 30–39 |
| Potato chips | 80–90 | Ice cream | 30–39 |
| White rice | 70–79 | Milk | 30–39 |
| Beans | 70–79 | Yogurt | 30–39 |
| Fresh potatoes | 70–79 | Meat and cheeses | 30–39 |
| Bread | 60–69 | Kidney Beans | 20–29 |
| Brown rice | 60–69 | Fructose | 20–29 |
| Muesli | 60–69 | Soybeans | 10–19 |
| Bananas | 60–69 | Nuts | 10–19 |
| Raisins | 60–69 | ||
| Mars chocolate bar | 60–69 | ||
| Buckwheat | 50–59 | ||
| Pasta | 50–59 | ||
| Sweet corn | 50–59 | ||
| Oat porridge | 50–59 | ||
| Peas | 50–59 | ||
| Yams | 50–59 |
A couple of surprises stand out in the chart. Carrots and honey sit in the same bracket as cornflakes. Fresh potatoes outscore bread. Ice cream and milk have a lower GI than brown rice – precisely because of their fat and protein. It’s a good example of why a single number can’t tell you whether a food is “healthy” or not.
Practical tips for taking the glycemic index into account
- Favor whole grains: buckwheat, oat flakes and brown rice keep the index in the 50–69 range.
- Add something protein-rich to every meal – yogurt, cottage cheese, eggs, meat. It lowers the GI of the whole meal.
- Vegetables before the main course: dietary fiber is the easiest way to slow carbohydrate absorption.
- After a workout, a higher GI can be useful – that’s when the body wants to restore its glycogen stores quickly.
- Eat sweets mindfully and work out whether they fit into your weekly calorie budget.
FAQ
Can you gain weight on low-GI foods?
You can. Body weight depends first and foremost on your calorie balance over the whole day. GI helps you make choices and keep hunger in check, but it doesn’t override the laws of energy balance.
Why is the GI of carrots high even though they’re considered healthy?
In cooked carrots the sugars are readily available and absorbed quickly. The portion, however, is small – a hundred-gram serving of carrots doesn’t do the same thing to your blood sugar as a hundred grams of bread. This is where glycemic load comes in, which also takes the amount into account.
Should you eat high-GI or low-GI food before a workout?
One to two hours before training, a lower-GI meal (oat flakes, whole-grain pasta) works well – the energy is released evenly. Right before a workout, or during longer sessions, a higher-GI snack (banana, honey) can provide quick fuel.
Count your calories: https://www.fitness.ee/kaloriarvuti/
Author: Mikk-Alvar Olle, translated from Günter Schlierkamp’s website
Source: WHO – healthy eating.
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