The glycemic index (GI) is a way of ranking carbohydrate-rich foods based on their effect on our blood sugar. The tests are conducted on human subjects. The result is a number or an index. Participants in the tests eat 50 grams of carbohydrates from various foods. Their blood sugar rise is then measured. This blood sugar rise is then compared to another test result, in which the blood sugar rise is measured after participants have drunk a glass of water mixed with glucose.
Whether a food has a high or low GI depends, among other things, on:
- How finely ground the food is. Whole grains and seeds versus finely ground flour. Apple juice versus a whole apple.
- How you prepare your food also matters. The less heat treatment, the lower the GI.
- The texture of the food. Is it crumbly or dense?
- Combine foods wisely to lower the GI. Mixing fast-digesting foods with slow-digesting ones lowers the overall GI. The presence of fiber and organic acids also lowers the GI. Examples include fermented dairy products and sourdough bread. The fat content of the food. Fat slows down gastric emptying.
The interaction between GI and insulin
Foods with a high GI cause high blood sugar levels and a large release of insulin. A large release of insulin leads to increased fat storage if glycogen stores are full and a positive energy balance has been achieved. Large fat stores lead to higher insulin levels due to increased insulin resistance, which sets off a vicious cycle.
To date, there are no credible studies showing that healthy people have a low GI. However, a low GI results in a low insulin response and can therefore likely reduce the risk of diseases such as diabetes and cardiovascular disease. Several studies have also shown that a low GI can lower both total cholesterol and LDL cholesterol. Foods with a low GI also often provide greater satiety and fewer calories.
Glycemic load (GL)
Relying solely on the GI is rather unreliable. The drawbacks of the GI are that it doesn’t provide any information about the type of fat in the food, the amount of protein it contains, the vitamins present, or the fiber content. Nor does the GI provide any information about the amount of carbohydrates in the food.
If you want a more nuanced result, you should use GB.
GB = GI × grams of carbohydrates per serving divided by 100
One cooked carrot: GI: 58 – GB: 4
Regular Snickers bar: GI: 55 – GB: 20
What foods can we use as a substitute for bread?
- Pumpernickel, Whole-grain bread, Schulzstad's coarse
- Wasa Fiber Plus or High-Fiber
- Mixed grains or oatmeal (fiber!)
- Omelet
- Salad
- Other (e.g., avocado with shrimp)
What products can we use to replace sugar?
- Fructose (tastes and is used like sugar)
- Sugar alcohol (used in the food industry)
- Oligofructose (liquid or powder)
- Stevia (drops or powder)
- Artificial sweeteners (sucralose, diet soda, etc.)
Worse alternatives to sugar include glucose, maltose, maltodextrin, and high-fructose corn syrup.