The glycemic index of a food corresponds to its ability to raise blood sugar levels, i.e., blood glucose. Glucose is the reference carbohydrate with a GI equal to 100.
The low-GI diet is actually based on the extensive research carried out by scientists Prof. Jenkins and Dr. Wolever. It involves favoring low glycemic index foods on a daily basis.
Indeed, the lower a food’s GI, the less it affects blood sugar levels. Conversely, high-GI foods promote high blood glucose, insulin spikes, and fat storage.
The GI diet has been shown to help with healthy weight loss and to better understand how our bodies function. Two studies also found greater losses of weight and fat mass in children and adolescents.
We strongly recommend it for diabetics, but not only for them. Why can controlling blood glucose with the low-GI diet help you improve your weight and health?
As a dietitian, I share with you the various studies on the subject and my nutritional advice to help you adopt it easily.
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1. We give plant-based foods a prominent place
All carbohydrates cause blood sugar to rise to a greater or lesser extent. And this glycemic spike occurs 30 minutes after their consumption.
Uniquely, most vegetables have a GI below 15, which is very low. Their high fiber content and nutritional composition are valuable assets.
Starting the meal with vegetables for better blood sugar is my first tip. Reserve at least half of your plate for them.
For example, you can choose a starter of grated carrots or vegetable sticks to snack on. Or eat a homemade soup before dinner, satiating effect guaranteed.
This meta-analysis confirms that weight loss is greater with a low-GI diet compared to other diets and that satiety would be improved by following this dietary approach.
| Food group | Low GI (0-55) | Moderate GI (55-69) | High GI (>70) |
| Fruits | Grapefruit (25) Apricot (34) Tomato juice (38) Apple, Pear (38) Prune (39) Apple juice (no added sugar) (44) Mango (51) Grape (53) | Papaya (56) Pineapple (59) Ripe banana (62) Orange (62) Raisins (64) Melon (65) | Watermelon (72) Dates (103) |
| Vegetables | Broccoli (10) Green beans, zucchini, leek, spinach, fennel, cabbage (15) Raw carrot (16) Cooked carrot (47) Squash (51) Boiled turnips (53) | Soup carton (60) Cooked beet (64) | Pumpkin purée (75) |
| Legumes and tubers | Soy, tofu (15) Split peas (22) Chickpeas (28) Lentils (32) Black beans (34) Peas (41) White beans, red beans (42) Cooked sweet potato (46) Cassava (46) Corn (52) | Potato chips (56) | Boiled potato (78) Fries (82) Baked potato (95) |
2. We prefer whole versions over refined foods
Processed foods and high GI (>70 or moderate >55) very often go hand in hand. Why? Because the various industrial processes often damage their fiber.
I’ll give you an example: white rice has a moderate GI (58) while the puffed rice cake has a high GI (85), same for quick-cook pouch rice (88).
It is preferable to choose the least processed form, that is the whole version for a lower GI, or semi-whole depending on your tolerances (taste and digestion).
These are also lower-quality carbohydrates that are generally used in industrial recipes: glucose-fructose syrup, white sugar… Combined with the low fiber content, this explains their impact on our blood sugar levels.
Because fiber acts as a buffer, especially soluble fiber (vegetables, legumes, apple, pear…). They slow gastric emptying and therefore the absorption of glucose by the body.
However, there are some surprising exceptions in the GI classification table. This is the case of Nutella or Twix, which appear in the low GI column, for example!
Results that still need to be qualified and can be explained by their high fat content. They slow the arrival of sugar in the blood. That does not make them essential calories for the body given their composition: sugar and palm oil are the first two ingredients of the famous spread.
| Food family | Low GI (0-55) | Moderate GI (55-69) | High GI (>70) |
| Cereal products & grains | Barley, pearl barley (28) Rye (40) Pasta al dente (45) Wholemeal bread, dark bread (49) Brown rice, red rice (50) Ebly wheat (50) Flour, rolled oats (52) Quinoa (53) | Basmati rice (58) Pizza (60) Gnocchi (60) Pasta cooked until soft (62) White rice (64) Couscous (65) Whole wheat bread (65) Rusks (68) | White bread (70) Pretzel (83) Puffed rice cakes (85) Quick-cook rice (88) White baguette (95) |
| Cookies & snacks | Nutella (33) All-Bran (34) Pepito (40) Twix, Snickers (43) Petit Beurre (Lu) (51) | Popcorn (55) Muesli (57) Plain crepe (66) Tuc (Lu) (67) | Chocolate bar (70) Granola bar (72) Baguette + spread (72) Donuts (76) Corn Flakes (77) Candies (>78) Energy drinks (90-95) |
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3. We don’t forget the good carbohydrates (but in reasonable amounts)
If quality matters, the quantity of carbohydrates does too.
Two other concepts have emerged: glycemic load (GL) and insulin index (II). Both complement the glycemic index.
GL and II provide more information about the portions of carbohydrate-containing foods consumed and the impact on blood glucose. Each is the result of a calculation:
- GL: (glycemic index x amount in grams) / 100. Below 10, the glycemic load is considered low, and it is considered high above 20.
- II: insulin index for 240 kcal of a food. Bread is the reference with an insulinemic index of 100.
Of course, consistencies can be observed with the GI table. However, eating too large a quantity of a low-GI food can cause the same disorders: too much sugar in the blood that the cells don’t need and that the body will store.
The recommended proportion of carbohydrates per day is 40 to 55% of the total daily caloric intake. So choose your ingredients carefully, in reasonable amounts.
| Food family | Low GI (0-55) | Moderate GI (55-69) | High GI (>70) |
| Sugars & sweeteners | Fructose, Agave (15) Coconut sugar (35) Strawberry jam (46) Brown sugar, Maple syrup (54) | Reduced-sugar jam (55) Honey (58) White sugar (65) | Corn syrup (85) Glucose (100) |
| Beverages | Kombucha (26) | Coca-Cola (58) Beer (66) | Grenadine syrup (70) |
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4. To lose weight without yo-yoing, pair proteins with low-GI foods
Two studies conducted in 2008 compared the consumption of low glycemic index foods with the Mediterranean diet in one and the low-carbohydrate diet in the other.
Better weight-loss results and a greater reduction in body fat with the low-GI diet were observed. These examples, among others, confirm the value of these dietary choices.
However, another essential nutrient seems to make a difference: protein. Essential for nourishing muscle mass, this study showed that the protein-enriched low-GI diet is the one that enables sustained weight loss and better stabilization.
This gave rise to the new low-GI diet, which adjusted the recommended daily protein amount to 20 to 25% of total energy intake.
Include enough animal proteins in main meals: lean meats, fish and shellfish, fatty fish twice a week, and eggs.
Then, incorporate daily low-GI plant proteins: lentils, chickpeas, kidney beans, green peas… They are ideal as an alternative to potatoes or other starchy foods with a higher GI — it’s a double advantage!
5. Choose healthy fats with a low glycemic index
Fats are essential for the proper functioning of the body. So there’s no question of eliminating them.
A study even compared the low-GI diet with a low-fat diet. Conducted among overweight adults in 2007, the benefit of a low-GI diet for weight loss was considerably greater.
On average, 25% of the total dietary intake of the GI diet should come from fats. Favor vegetable fats in your dishes: olive oil, flaxseed, canola…
Good news, some low-GI foods are also sources of healthy fats. This includes oilseeds: walnuts, peanuts, hazelnuts, almonds…
I recommend incorporating them regularly as low-GI snacks: a handful of nuts at breakfast and at 4 p.m., a chopped apple with peanut butter.
Choose avocado or tofu instead of cheese, which is high in saturated fats, for example. Fatty foods are not forbidden; choose them more wisely to take care of your cardiovascular system.
| Food family | Low GI (0-55) | Moderate GI (55-69) |
| Nuts & seeds | Pecans (10) Roasted salted peanuts (14) Walnuts, pistachios, almonds (15) Cashews (22) | |
| Milks, yogurts & derivatives | Greek yogurt (11) Whole milk, semi-skimmed (27-30) Skimmed fruit yogurt (28) Almond milk, oat milk (30) Sweetened yogurt (33) Soy milk (36) | Ice cream (61) Sweetened condensed milk (61) Chocolate milk (64) |
6. Follow the recommendations for low-GI meals
To avoid blood sugar spikes, how you prepare your meals matters.
Here are my tips to lower the glycemic index of your meals:
- opt for complete meals with protein, vegetables and fat rather than a carbohydrate-only food
- prefer short cooking times and reheat your dishes in the microwave
- limit the amount of water when cooking your vegetables, keeping them whole or in large pieces
- eat your moderate or high GI foods rather cold (potatoes, rice…)
- add a note of acidity such as vinegar or lemon
When your body receives too much sugar, it stores the excess as fat. This is followed by a drop in insulin, then in blood sugar, very often resulting in the urge to eat again. Your body becomes exhausted.
These tips help you promote a stable blood sugar level for more energy. A tasty piece of fruit with plain yogurt and pistachios will put you in a good mood, rather than a piece of baguette.
7. A diet without bans that offers many benefits
The new low-GI diet recommends three phases to lose weight gradually. In the first days, include only very low GIs <20. Then low GIs <55 until you reach your goal.
Next, to stabilize: low and moderate GI can be included in your new routine.
Unlike other dietary programs, the low-GI diet does not ban carbohydrates but is a genuine strategy.
The low-GI diet can be suitable for the whole family, which I consider a real advantage. For pregnant women and people with diabetes, nutritional support is necessary at the beginning to adjust meals (timing, quantities…).
Beyond weight loss, the other benefits of the low-GI diet are numerous: improved cognitive function, reduction of inflammation, reduced insomnia…
Now you know everything! You have the nutritional guidelines to better choose your foods, prepare your next shopping trips well, improve your habits and your mood.
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Sources and scientific studies
Cara B Ebbeling, Michael M Leidig, Kelly B Sinclair, Jan P Hangen, David S Ludwig, 2003. A reduced-glycemic load diet in the treatment of adolescent obesity.
Iris Shai, Dan Schwarzfuchs, Yaakov Henkin, Danit R Shahar, Shula Witkow, Ilana Greenberg, 2008. Dietary Intervention Randomized Controlled Trial (DIRECT) Group – Weight loss with a low-carbohydrate, Mediterranean, or low-fat diet.
Jennie Brand-Miller, Joanna McMillan-Price, Katherine Steinbeck, Ian Caterson, 2008. Carbohydrates the good, the bad and the whole grain.
E E J G Aller, T M Larsen, H Claus, A K Lindroos, A Kafatos, A Pfeiffer, J A Martinez, T Handjieva-Darlenska, M Kunesova, S Stender, W H M Saris, A Astrup, M A van Baak, 2014. Weight loss maintenance in overweight subjects on ad libitum diets with high or low protein content and glycemic index: the DIOGENES trial 12-month results.
Cara B. Ebbeling, Michael M. Leidig, Henry A. Feldman, et al, 2007. Effects of a Low–Glycemic Load vs Low-Fat Diet in Obese Young Adults, A Randomized Trial.
Yeonsoo Kim, Jie Chen, Michael D Wirth, Nitin Shivappa, James R Hebert, 2018. Lower Dietary Inflammatory Index Scores Are Associated with Lower Glycemic Index Scores among College Students.
James E Gangwisch, Lauren Hale, Marie-Pierre St-Onge, Lydia Choi, Erin S LeBlanc, Dolores Malaspina, Mark G Opler, Aladdin H Shadyab, James M Shikany, Linda Snetselaar, Oleg Zaslavsky, Dorothy Lane, 2020. High glycemic index and glycemic load diets as risk factors for insomnia : analyses from the Women’s Health Initiative.
