Glycemic index and insulin reaction


Why would you be more interested in glycemic index (GI) than in the amount of sugar or fat in your diet ?

The GI is a tracker of how fast carbohydrates (= sugar) enter the bloodstreams and increase our blood glucose level consequently.

Why is it important?

A high blood glucose level can have very harmful consequences on our health, it is therefore highly controlled by our organism. The hormone in charge of maintaining the blood glucose level at a constant rate is insuline. it is produced by our pancreas when we digest glucose, and its role is to help distribute and stock glucose in our body so it can be used later. Glucose is therefore transformed into fat, which is a very efficient form of storage, but most of us don’t want that!

Insuline peak = fat storage = weight gain

A second benefit in maintaining a constant blood glucose level is to avoid tiredness or cravings due to hypoglycemia (that means our body lacks sugar). When insuline production doesn’t work well, as in Diabetes for example, blood glucose level can be very high and glucose becomes poisonous for our body.

In the end, maintaining a constant blood glucose level compels our body to draw on fats as energy ressources when it doesn’t have anymore sugar.

Not bad, huh?

How do we avoid insuline peak?

Each food containing high amount of carbs (sugar) must be accompanied with lipids (fats) and proteins (from animals or from plants). Indeed, fats and proteins slow carbs absorption, but of course this is not about eating high amount of fat either! Whereas fatty food have a low IG, they are also stoked by our body directly into… fat.

For example for breakfast, instead of eating a banana (carbs) with cereals (carbs), you can chose to eat your banana with unsweetened cottage or white cheese (proteins) and a handful of almonds or nuts (fats).

Reasonably associate fats when eating sugar will slow glucose entering the bloodstream and will limit the insuline peak, leading to a lesser storage of sugar by our body.

How does it works? Fat slow gastric emptying, which is the crossing from our stomach to our intestine. Carbs being absorbed in our intestine, they arrive more slowly and therefore the speed of glucose entering the bloodstream is slowed accordingly.

Another mean to slow digestion is to prefer « al dente » or minimal cooking process. The more a food is cooked, the higher the GI because cooking act as a « pre digestion » for our body, leading to more accessible carbs.

Practical application

Leguminous (lentils, beans – red, white, black – peas like chickpeas…) are also interesting sources of carbs when not cooked too much. They all have a low GI as they have slow digestible starch and contain fibers.

Cereals are tricky, as they are a good option when they are not transformed… Which is rarely the case! Breakfast cereals are usually cooked or transformed a lot, and therefore are to be avoided. Prefer oatmeals and don’t cook them too much, or other cereals that contains fibers (the more fiber = the slowest digestion = the slowest blood glucose enter the bloodstream).

Rice and sweet potatoes are interesting, in particular when served cold in salads for example : when the starch is cold, it is more dense and is therefore digested more slowly. Rice is to be preferred from pastas, as it is more often served with white meat or fish which reduce the overall caloric intake of the meal and bringing good quality starch. Whole grain wheat pastas are to be preferred from regular because they contain fibers.

Improve your meals taste by using herbs or spices instead of sauces.

What about your drink?

Sodas are obviously to limit as possible, even sugar free sodas. Non caloric sweeteners send a « sugar is coming » message to our brain, who gets used to have its « dose » of sugary taste and will ask for it in the future. If you really don’t like the taste of water, you can improve it with lemon or mint, or take sparkling water instead of still.

Try not to…

Mix, grind or crush food as the fibers and the starch are then degraded which increases the speed of glucose entering bloodstream.

Bread consumption should be exceptional, in particular white bread or sandwich loaf. If you eat bread, prefer whole grains or cereals bread.

Limit your consumption of dairies as they usually contain a lot of sugar in the form of lactose or added sugar (flavored yoghurt or milk, ice cream…). Unlike what most people think, cheese and yoghurt don’t contain lactose which has been « digested » by lactic ferments. However, cheese often contain high amount of fat and yoghurt high amount of added sugar, so they should be limited too.

Avoid breakfast cereals, in particular extruded, expanded or puffed cereals (as Captain Crunch or Corn Flakes). Transformation and cooking of these cereals make them vey much equivalent as sugar. As said before, oatmeals and less transformed cereals are a better option.

Fruits are ok but some rules are to be followed, as they can contain massive amount of sugar. First, some fruits should be eaten not ripe, as bananas, and some should be avoided because of the amount of sugar and the low amount of fibers, as grape or cherries. Always eat fruits under a solid form and not as juices, which are sugar tricks under their healthy looks.

Limit alcohol consumption : cocktails, wine glasses and beers bring a lot of sugar in the diet, and make us forget very fast our « good resolutions »…


To help you, here is a list of food with a low impact on your blood glucose level. They can be part of a balanced diet when consumed in reasonable amounts.

A diet is to be considered on a whole week, beware of weekends and its share of parties, barbecues and brunches…

For a balanced diet : legumes 4 times a week, eggs 4 times a week, fish 2 times a week, white meat 2 times a week, red meat one time a week, vegetables at every meal, dairies 2 or 3 times a week and fruits everyday.


Prefer water to any other option (even sugar free)


Eggplant, broccoli, mushroom, cabbage, zucchini, spinach, green beans, leeks, peppers, asparagus, avocado, artichoke, beet, carrot, cucumber, watercress, corn salad, sweet potato, pumpkin, tomato, lettuce, turnip.

Legumes and starchy food

Beans (all), lens (all), peas, chickpeas, soybeans. Rice, quinoa, buckwheat, oatmeal.
Bread: wholewheat, linen or multigrain.


Fish: Herring, mackerel, sardines, salmon, trout, shrimp, seafood. Eggs. Meat: chicken, turkey, pork, duck, veal.


Yoghurt: unsweetened, to decorate with pieces of fruit. Milk: with moderation
Sheep milk cheese, preferably goat and with moderation.


Raspberry, blueberry, blackberry, apricot, citrus (orange, lemon, clementine, grapefruit), banana (not too ripe), cassis, fig, strawberry, guava, pomegranate, currant, persimmon, kiwi, mango (not too ripe) melon, watermelon, peach, pear, plum.

Dry fruits

Dates, figs, prunes, raisin, apricot.

Nuts and grains

Almonds, walnuts, hazelnuts, Brazil nuts, macadamia nuts, sesame seeds, flax.


Chocolate > 70% cocoa. Sugars to avoid as possible. For less “transformed” options, choose honey, maple syrup or agave syrup …

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