The low glycemic (low GI) diet revolves around the concept of the glycemic index (GI), a tool that can guide you in choosing high-quality carbohydrates. Studies suggest this diet may aid in weight loss, reduce blood sugar levels, and decrease the risk of heart disease and type 2 diabetes. However, the way it ranks foods has faced criticism for being unreliable and not always reflecting a food’s overall healthiness.
Understanding the Glycemic Index (GI)
The glycemic index (GI) is a measurement system that ranks foods based on their effect on your blood sugar levels. It was developed in the early 1980s by Dr. David Jenkins, a Canadian professor. The rates at which different foods raise blood sugar levels are ranked in comparison with the absorption of 50 grams of pure glucose, which has a GI value of 100 and serves as a reference food.
GI Ratings
The three GI ratings are:
- Low: 55 or less
- Medium: 56 to 69
- High: 70 or more
Foods with a low GI value are slowly digested and absorbed, leading to a slower and smaller rise in blood sugar levels, making them the preferred choice. On the other hand, foods with a high GI value are quickly digested and absorbed, resulting in a rapid rise and fall of blood sugar levels, and should be limited.
Factors Influencing GI Value
A number of factors can influence the GI value of a food or meal:
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- The type of sugar it contains: The GI of sugar ranges from as low as 23 for fructose to up to 105 for maltose. Therefore, the GI of a food partly depends on the type of sugar it contains.
- The structure of the starch: Starch is a carb comprising two molecules: amylose and amylopectin. Amylose is difficult to digest, while amylopectin is easily digested. Foods with a higher amylose content will have a lower GI.
- How refined the carb is: Processing methods like grinding and rolling disrupt amylose and amylopectin molecules, raising the GI. Generally speaking, the more processed a food is, the higher its GI.
- Nutrient composition: Adding protein or fat to a meal can slow digestion and help reduce the glycemic response to a meal.
- Cooking method: Preparation and cooking techniques can affect the GI too. Generally, the longer a food is cooked, the faster its sugars will be digested and absorbed, raising the GI.
- Ripeness: Unripe fruit contains complex carbs that break down into sugars as the fruit ripens. The riper the fruit, the higher its GI. For example, an unripe banana has a GI of 30, while an overripe banana has a GI of 48.
Glycemic Load (GL)
The rate at which foods raise blood sugar levels depends on three factors: the types of carbs they contain, their nutrient composition, and the amount you eat. To solve this, the glycemic load (GL) rating was developed. The GL is a measure of how a carb affects blood sugar levels, taking both the type (GI) and quantity (grams per serving) into account.
- Low: 10 or less
- Medium: 11 to 19
- High: 20 or more
The GI is still the most important factor to consider when following the low GI diet. Otherwise, the easiest way to aim for a GL under 100 is to choose low GI foods when possible and consume them in moderation.
Benefits of a Low GI Diet
Research suggests that low GI diets reduce blood sugar levels in people with diabetes. A 2019 review of 54 studies concluded that low GI diets reduced hemoglobin A1C (a long-term marker of blood sugar control), body weight, and fasting blood sugar levels in people with prediabetes or diabetes. Some research has linked high GI diets with a greater risk of developing type 2 diabetes. The low GI diet has also been shown to reduce the risk of macrosomia, a condition in which newborns have a birth weight over 8 pounds and 13 ounces, and it’s associated with numerous short- and long-term complications for the mother and baby.
Studies have shown that the low GI diet may also have other health benefits:
- Improved cholesterol levels: A 2019 study showed that low GI diets reduce total cholesterol and LDL (bad) cholesterol. LDL is associated with an increased risk of heart disease and stroke.
- May help you lose weight: Some evidence from 2020 suggests that low GI diets can promote fat loss. However, more research is needed to determine whether low GI diets are effective for long-term weight loss.
- May reduce the risk of cancer: Some research suggests that people who consume high GI diets are more likely to develop certain types of cancer, including endometrial, colorectal, and breast cancer, compared with people on low GI diets.
- May reduce the risk of heart disease: Research has strongly associated high GI and GL diets with an increased risk of heart disease.
How to Follow a Low GI Diet
There’s no need to count calories or track your protein, fat, or carbs on the low GI diet. Instead, the low GI diet involves swapping high GI foods for low GI alternatives. There are plenty of healthy and nutritious foods to choose from. You should build your diet around the following low GI foods:
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- Bread: whole grain, multigrain, rye, sourdough
- Breakfast cereals: steel cut oats, bran flakes
- Fruit: apples, strawberries, apricots, peaches, plums, pears, kiwi, tomatoes
- Vegetables: carrots
- Starchy vegetables: sweet potatoes with an orange flesh, corn, yams, winter squash
- Legumes: lentils, chickpeas, baked beans, butter beans, kidney beans
- Pasta and noodles: pasta, soba noodles, vermicelli noodles, rice noodles
- Rice: basmati, Doongara, long grain, brown
- Grains: quinoa, barley, pearl couscous, buckwheat, freekeh, semolina
- Dairy and dairy replacements: milk, cheese, yogurt, coconut milk, soy milk, almond milk
The following foods contain few or no carbs and therefore don’t have a GI value. These foods can be included as part of the low GI diet:
- Fish and seafood: including salmon, trout, tuna, sardines, prawns
- Other animal products: including beef, chicken, pork, lamb, and eggs
- Nuts: such as almonds, cashews, pistachios, walnuts, macadamia nuts
- Fats and oils: including olive oil, butter, avocado
- Herbs and spices: such as garlic, basil, dill, salt, pepper
- Non-starchy vegetables: such as broccoli, cauliflower, celery, and zucchini
Foods to Limit
Nothing is strictly banned on the low GI diet. However, try to replace these high GI foods with low GI alternatives as much as possible:
- Bread: white bread, bagels, naan, Turkish bread, French baguettes, Lebanese bread
- Breakfast cereals: instant oats, Rice Krispies, Cocoa Krispies, Corn Flakes, Froot Loops
- Starchy vegetables: Désirée and Red Pontiac potato varieties, instant mashed potatoes
- Pasta and noodles: corn pasta and instant noodles
- Rice: Jasmine, Arborio (used in risotto), Calrose, medium-grain white
- Dairy replacements: rice milk and oat milk
- Fruit: watermelon
- Savory snacks: rice crackers, Corn Thins, rice cakes, pretzels, corn chips
- Cakes and other sweets: scones, doughnuts, cupcakes, cookies, waffles, cakes
- Other: jelly beans, licorice, Gatorade, Lucozade
Low GI Breakfast Ideas
Here are some low-GI breakfast ideas to help you rise and shine!
- Greek Yogurt with Berries: Greek yogurt is a high-protein, low GI option. Rich in probiotic bacteria, Greek yogurt can support a healthy gut microbiome which can also aid in blood sugar control and weight management. Top your yogurt with low GI fruits like strawberries and blueberries that are rich in fiber and antioxidants. Add nuts and seeds for extra protein and healthy fats as well as a satisfying crunch.
- Oatmeal with Chia Seeds: Use rolled or steel-cut oats and low-fat milk for your oatmeal. Sprinkle in some nuts for protein, cinnamon for flavor, and a dash of pure, organic vanilla extract or honey for sweetness. Mix in chia or ground flaxseeds for additional fiber as well as omega-3 fats. For added protein, try a side of scrambled eggs.
- Avocado Toast on Whole Grain Bread: Avocados provide healthy fats and fiber. Spread mashed avocado on a slice of whole grain toast for a lower GI score option. Add a lean protein source, such as an egg, smoked salmon, or cottage cheese to round out this healthy low glycemic breakfast.
- Smoothie with Spinach, Banana, and Unsweetened Almond Milk: Whip up a smoothie as a quick, convenient, and healthy breakfast option. Throw in a generous handful of spinach, which is a highly nutritious, low GI vegetable. Add a banana for sweetness and nutrients like potassium and vitamin C. You can use unsweetened almond milk as a low GI dairy alternative. Be sure to also add a protein source such as a high quality protein powder.
- Cottage Cheese with Cucumber and Tomatoes: Cottage cheese is a high-protein, low glycemic food. Combine cottage cheese with low GI vegetables like chopped cucumber and tomatoes. Mix in seasonings like basil, garlic powder, and a drizzle of olive oil. Eat with a spoon or as a dip with whole grain crackers.
- Quinoa Breakfast Bowl with Nuts and Berries: Quinoa has a low GI score, which is lower than some other grains like white rice and brown rice. Not only for savory dishes, quinoa can be a great base for a healthy breakfast bowl. Mix in nuts, berries, and cinnamon. You can even try cooking quinoa in coconut or almond milk for a creamy, low GI twist!
- Egg White Omelet with Vegetables: Egg whites are a good source of protein with a GI of zero because they have a minimal effect on blood sugar levels. Sauté some flavorful, non-starchy veggies like mushrooms, onions, spinach, and tomatoes into an egg scramble or omelet. Cook with non-starchy vegetables such as spinach, bell peppers, or broccoli and your favorite seasonings. Serve with low GI fruit and a half of an avocado for a well balanced and colorful breakfast.
- Chia Pudding with Unsweetened Soy Milk and Fruit: Chia seeds create a high-fiber, low GI pudding when combined with unsweetened soy milk. Soy milk is a low-GI milk alternative that naturally contains protein. Top with low GI fruits like chopped apples. You can also mix in protein powder or Greek yogurt to boost the protein content. For a convenient and hassle-free breakfast option, prepare your chia pudding the night before and refrigerate for a delicious breakfast ready to go when you wake up.
- Breakfast Burrito: To make a blood sugar-friendly breakfast burrito, start with a whole wheat tortilla. Then add low-glycemic ingredients such as: Eggs or scrambled tofu, Beans (black beans, pinto beans, etc.), Veggies (spinach, bell peppers, mushrooms, onions, etc.), Avocado, Salsa and Cheese. Try making a batch of burrito filling at the beginning of the week for easy morning assembly.
- Black Bean Breakfast Tacos: Try breakfast tacos for a low-prep and blood sugar-friendly meal. Add sautéed black beans, zucchini, mushrooms, and onions to corn tortillas. Top with salsa, avocado, and cilantro. If you prefer a higher protein breakfast, you can add options like Lean ground beef, Shredded chicken, or Scrambled eggs or tofu.
- Warm Bean Bowl: If you thought beans weren’t a breakfast choice, think again! Warm up a bowl of butter beans, black beans, lentils, or chickpeas. Top these with eggs, avocados and other non-starchy veggies, and a sprinkling of low-fat cheese.
- Yogurt with Apple and Peanut Butter: Begin with low-fat vanilla yogurt and mix in an apple and a healthy scoop of peanut butter.
- Broiled Grapefruit: The grapefruit can be a little sour first thing in the morning, but you can broil grapefruit halves to caramelize the fruit’s natural sugars. Then add a dusting of cinnamon - or chili flakes for a kick.
- Greek Yogurt Muffins with Apples and Rolled Oats: There are plenty of yummy recipes out there to satisfy your low-GI cravings! We love these Greek yogurt muffins with apples and rolled oats.
Sample Low GI Meal Plan
This sample menu shows what 1 week on the low GI diet might look like. Feel free to adjust this or add low GI snacks based on your own needs and preferences.
Monday
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- Breakfast: oatmeal made with rolled oats, milk, pumpkin seeds, and chopped, fresh, low GI fruit
- Lunch: chicken sandwich on whole grain bread, served with a salad
- Dinner: beef stir-fry with vegetables, served with long grain rice
Tuesday
- Breakfast: whole grain toast with avocado, tomato, and smoked salmon
- Lunch: minestrone soup with a slice of whole grain bread
- Dinner: grilled fish served with steamed broccoli and green beans
Wednesday
- Breakfast: omelet with mushrooms, spinach, tomato, and cheese
- Lunch: salmon, ricotta, and quinoa cups with a salad
- Dinner: homemade pizzas made with whole wheat bread
Thursday
- Breakfast: smoothie with berries, milk, Greek yogurt, and cinnamon
- Lunch: chicken pasta salad made with whole wheat pasta
- Dinner: homemade burgers with beef patties and vegetables on whole wheat rolls
Friday
- Breakfast: fruity quinoa porridge with apple and cinnamon
- Lunch: toasted tuna salad sandwich on whole wheat bread
- Dinner: chicken and chickpea curry with basmati rice
Saturday
- Breakfast: eggs with smoked salmon and tomatoes on whole grain toast
- Lunch: whole grain wrap with egg and lettuce
- Dinner: grilled lamb chops with greens and mashed pumpkin
Sunday
- Breakfast: buckwheat pancakes with berries
- Lunch: brown rice and tuna salad
- Dinner: beef meatballs served with vegetables and brown rice
Low GI Snack Ideas
If you find yourself hungry between meals, here are a few healthy low GI snack ideas:
- a handful of unsalted nuts
- a piece of fruit like apple slices with nut butter, almond butter, or peanut butter
- carrot sticks with hummus
- a cup of berries or grapes served with a few cubes of cheese
- unsweetened Greek yogurt with sliced almonds
- a hard-boiled egg
- low GI leftovers from the night before
Drawbacks of the Low GI Diet
Although the low GI diet has several benefits, it also has a number of drawbacks.
First, the GI doesn’t provide a complete nutritional picture. It’s important to also consider the fat, protein, sugar, and fiber contents of a food, regardless of its GI. For example, the GI of frozen french fries is 75. Some varieties of baked potato, a healthier alternative, have a GI of 93 or more. In fact, there are many unhealthy low GI foods, such as candy bars and ice cream.
Another drawback is that the GI measures the effect of a single food on blood sugar levels. However, most foods are consumed as part of a larger mixed meal, making the GI difficult to predict in these circumstances.
Lastly, GI doesn’t take into account the number of carbs you eat. However, this is an important factor in determining their effect on your blood sugar levels. For example, watermelon has a high GI of 72 to 80 and wouldn’t be considered the best option when following a low GI diet. However, watermelon also has a low carb content, containing under 8 grams of carbs per 100 grams. A typical serving should have minimal effect on blood sugar levels. This highlights that using GI in isolation may not always be the best predictor of blood sugar levels.
Benefits of low glycemic breakfasts
Starting your day with a low glycemic breakfast can help stabilize blood sugar levels throughout the morning. It can even set you up for better blood sugar control for the rest of the day. Stable blood sugar levels can also help with weight management and keeping hunger at bay, reducing the likelihood of overeating by promoting a sense of fullness and satiety. Moreover, incorporating low GI foods into your morning routine can have long-term health benefits. High blood sugar and insulin levels are risk factors for developing type 2 diabetes, high blood pressure, high cholesterol, and heart disease. Additionally, maintaining stable blood sugar levels can improve mental clarity and focus, allowing you to start your day with better cognitive function and productivity.
Tips for Incorporating Low-Glycemic Breakfast Foods into Your Routine
To get started with a low glycemic diet, make higher fiber swaps for typical breakfast foods. For example, you can substitute:
- Whole grain bread instead of white bread.
- Steel cut or old-fashioned oats instead of quick oats.
- A whole grain bagel instead of a white bagel.
- Bran cereal instead of sugary cereal.
In general, try to emphasize whole foods for breakfast. Preparing your morning meal at home is the best way to accomplish this. If time is a barrier, try low-GI breakfast recipes that work well for meal prep, such as:
- Overnight oats.
- Egg bites.
- Baked oatmeal.
- Freezer breakfast burritos.
Who Should Monitor Glycemic Index?
Paying attention to the glycemic index of the foods you eat can be helpful if you have diabetes. Research shows that focusing on low-GI, high-fiber meals is a beneficial strategy for blood sugar management. Other metabolic conditions may also benefit from low glycemic index meals, such as:
- Polycystic ovarian syndrome (PCOS).
- Overweight or obesity.
- Heart disease.
However, many studies are conflicting, and more research is needed to fully understand the role of glycemic index in these conditions.