The glycemic index (GI) is used to measure the effect of carbohydrate-containing foods on blood glucose levels. A low glycemic diet, or low GI diet, aims to limit foods that cause blood glucose levels to spike.
A food’s glycemic index is calculated by comparing it to a reference food, such as white bread or glucose. After this comparison, it may be rated low, medium, or high GI. Low GI refers to a low, slow rise in blood glucose. High GI refers to a high, fast rise.
Read more about the glycemic index, including its classifications.
There are several factors that can affect the glycemic index of a food, including:
- Cooking and processing: Processing and cooking techniques can affect how sugar is digested. Cooking a food for longer may raise its GI.
- Sugar type and structure: The type and structure of sugar a food contains may impact its GI. Foods high in fructose and amylose may have a lower GI.
- Composition: Other factors, such as what nutrients a food contains, may affect its glycemic response during digestion. Eating the food alongside fat, fiber, and protein may help lower the response.
- Refinement: Refined carbohydrates may have a higher GI.
- Ripeness: According to research, the riper a fruit or vegetable, the higher its GI may be.
Below are some potential benefits of eating a low glycemic diet, according to research.
Diabetes
Uncontrolled blood sugar is a common trait of type 2 diabetes. Research suggests that a low GI diet may help stabilize blood sugar levels by reducing spikes after eating.
A 2019 meta-analysis looked at the effects of low GI diets on blood glucose. It concluded that low GI diets may help reduce markers of blood sugar and fasting blood glucose levels.
Acne
Several studies have suggested that a low glycemic diet may reduce acne lesions.
According to a 2018 randomized control trial, a low glycemic diet may decrease a substance in the body that contributes to the development of acne.
Weight management
A 2019 meta-analysis suggests that low GI diets may result in a small but significant reduction in body mass.
A low GI food is a food that has a score of 55 or less.
Examples of foods that have a moderate to low GI include:
- some whole grains, such as rolled oats, corn, and barley
- non-starchy vegetables, such as dark leafy greens and cruciferous vegetables
- legumes, such as beans and pulses
- fruits, such as:
- berries
- citrus fruits
- stone fruits
- apples
- avocados
Read more about leafy green and cruciferous vegetables.
Foods without or with a low GI value can also form part of a low GI diet. They include:
- meat and poultry
- fish and seafood
- dairy
- plant oils, such as olive oil
- nuts
- seeds
- herbs and spices
A low glycemic diet can also include consuming foods in a specific order. An example might be eating protein and fat sources before carbohydrates.
Learn more about fiber and protein servings.
A low glycemic diet encourages limiting foods with a GI score over 55. Examples of foods with a high GI include:
- sugar-sweetened foods and beverages, such as candy and soda
- refined grains, such as white pasta, bread, and rice
- some cereals
- starchy vegetables, such as potatoes, corn, and pumpkin
- baked goods
- some prepared snacks and meals and other highly-processed foods, such as chips
Always contact a doctor before making dietary changes
A diet that is appropriate for one person may not be appropriate for another. This can be especially true for someone with underlying health conditions.
Always contact your doctor before making substantial dietary changes. They can discuss ways to improve your health through certain dietary plans.
Below are example ideas of low glycemic diet meals.
| Breakfast | Lunch | Dinner | |
|---|---|---|---|
| Monday | oatmeal with flax seeds, pumpkin seeds, and apple | rainbow salad with Italian dressing and grilled chicken | salmon with vegetables and quinoa |
| Tuesday | chia pudding with nonfat Greek yogurt and berries | salad vegetables with feta cheese, olive oil, and vinegar | zucchini noodles and ground beef with no added sugar tomato sauce |
| Wednesday | peanut butter on whole grain toast with added fruit | mixed bean soup with vegetables and tofu | angus burger with lettuce wrap and salad |
| Thursday | overnight oats with nut butter and stone fruits | couscous and mixed bean salad | branzino with salad vegetables |
| Friday | poached eggs and avocado on sourdough toast | stuffed zucchinis with pesto, ground beef, and vegetables | pizza with a cauliflower or whole grain crust, topped with vegetables and mozzarella |
| Saturday | omelet with spinach, mushrooms, and onions | quinoa with feta, red onion, tomatoes, and hummus | grilled lamb with broccoli and couscous |
| Sunday | buckwheat pudding with seeds and sliced apple | tuna salad sandwich with salad on the side | lentil and tofu curry |
Low GI snacks can include:
- dark chocolate with 85% cocoa or more
- unsalted nuts and seeds
- hard-boiled eggs
- seasonal, low GI fruit and nut butters
- low GI vegetables, such as celery or carrots, and hummus
- Greek yogurt
You may need to modify portion sizes and food choices based on your health requirements and preferences.
The glycemic index does not account for certain factors that may be important for maintaining a healthy diet.
A food’s glycemic index does not reflect its overall nutritional value. Using only the glycemic index may mean you miss out on a diversity of nutrients.
According to a 2018 review, focusing on overall dietary quality may be more important for managing chronic conditions.
Everyone’s body is unique and may respond to sugar differently. Because of this, GI alone may not be the most reliable measure of blood sugar levels.
Contact your doctor or a registered dietician if you have questions about the glycemic index.
The glycemic index does not account for the total amount of carbohydrates you consume in a serving.
This may mean you end up eliminating some high GI foods, despite them not being high in carbohydrates or significantly affecting blood sugar. Watermelon is an example of this. It has a high GI score but is low in overall sugar per serving.
Glycemic load (GL) tries to address this by taking into account carbohydrate serving size. As a result, it may be a more effective measure of a food’s impact on blood sugar.
To calculate GL, multiply the grams of carbohydrates in a serving by the food’s GI. Then, divide that number by 100. Results can be categorized as follows:
- High GL: 20 or higher
- Medium GL: 19–11
- Low GL: 10 or lower
A low glycemic diet aims to minimize blood sugar spikes after eating.
Low glycemic index foods include non-starchy fruits and vegetables, whole grains, and legumes. Sources of protein such as meat and tofu can also be included.
There are limitations to the glycemic index, such as accounting for overall nutrition in your diet. Contact your doctor or a registered dietitian before making significant dietary changes.
