What Is a Low Glycemic Diet?
The glycemic index is a tool that’s used to indicate how a particular food affects blood sugar (or glucose) levels. The definition of the glycemic index (GI) is “a measure of the blood glucose-raising potential of the carbohydrate content of a food compared to a reference food (generally pure glucose, or sugar).”
Foods are assigned a glycemic index/glycemic load number that can be compared to pure glucose, which serves as the benchmark for all other foods. Pure glucose has a glycemic index number of 100, indicating that it’s very rapidly broken down into glucose once eaten and then either sent to cells to be used for energy, saved in the muscles as glycogen for later use or stored inside fat cells when there’s a surplus.
All foods containing glucose, fructose or sucrose (various forms of carbohydrates or sugars) can be classified as high GI, moderate GI or low GI. (1) The glycemic index values of all foods range from 0–100:
- High GI = 70 to 100
- Medium GI = 50 to 70
- Low GI = below 50
Whenever we eat any type of carbohydrate, whether it’s pure table sugar or a cup of fresh vegetables, the molecules in the food are broken down as they’re absorbed, which impacts blood glucose levels and insulin release. All carbohydrates cause release of the hormone insulin from the pancreas, which has the job of picking up and sending glucose that’s present in the blood throughout the body to be used or stored away. (2)
How drastically and quickly a carbohydrate causes this process to happen depends on how quickly its glucose is broken down; some carbs that are low on the glycemic index (like veggies and 100 percent whole grains, for example) cause a smaller and more gradual rise in blood glucose, while carbs that have a high glycemic score (like soda and white rice) cause rapid glucose absorption and high insulin release. Carbohydrates of all kinds are the main dietary source of glucose, but not all carbs are created equal. For example, good choices include brown or wild rice, sweet potatoes, sprouted ancient grains, legumes, and beans, while poor choices include soda and ice cream.
Choosing low glycemic foods can help prevent persistently high insulin levels, which are associated with health problems like type 2 diabetes or prediabetes, heart disease, hypertension, and obesity.
Glycemic Index vs. Glycemic Load
Finally, it’s important to understand that a glycemic index score is a bit different than a glycemic load (GL) score. GL takes into account the GI score of a particular carbohydrate but also considers how the carbs in the food affect blood sugar levels when eaten in average portions (not just in 100-gram servings). Many of the fruits and vegetables that are high on the glycemic index scale come in low on the glycemic load scale. Overall, a food’s glycemic load score may be a better predictor of whether or not when eaten in moderate amounts as part of a whole meal it’s generally a healthy choice or not. Here’s the range of GL scores to consider when making choices about the carbs in your diet:
- High GL = 20 +
- Medium GL = 11 to 19
- Low GL = 10 or less
How a low glycemic diet compares to low-carb diet:
- In many ways, a low glycemic diet can also be called a “slow carb diet.” There are many low-carb foods that also qualify as low glycemic foods because of their ability to prevent a strong release of insulin and blood sugar fluctuations after eating.
- For example, low-carb foods like fish, meat, oils and fats have a GI score of zero since they contain no sugar/starch/carbs, and therefore in general they don’t significantly impact blood glucose or insulin levels.
Top 10 Low Glycemic Diet Foods and Food Groups
A low glycemic diet includes lots of foods that are considered “complex carbs” but fewer that are “simple carbs.”
- Simple carbohydrates: These consist of foods that contain one or two simple sugars. Foods that are simple carbs include those with added/table sugar, desserts, processed grains, candy, jam, soda, etc. However, not all simple carbohydrates are unhealthy; fruits like apples, strawberries, peaches and others are also “simple carbs” but can still be part of a balanced diet.
- Complex carbohydrates: These are foods that consist of long chains of simple sugars. Foods such as beans, legumes, many veggies, oatmeal, bran, wheat germ and more are examples of complex carbohydrates. (3)
Based on factors like nutrient density, some of the least processed low glycemic foods you can eat include: (4)
- Non-Starchy Vegetables — Most veggies are very low GI, with GL values between about 1–7. Try to include these with every meal, especially all types of lettuce and leafy greens, broccoli, spinach, onion, green beans, artichokes, peppers, and others.
- Nuts and Seeds — Nuts and seeds range somewhat considerably in GL scores, from about 1–17 per serving (cashews have the highest). Look for chia seeds, flaxseeds, pumpkin seeds, almonds, and walnuts, which are some of the best choices.
- Beans and Legumes — Beans and legumes have GL values between about 2–13 per serving (soybeans have the lowest, while chickpeas are a bit higher). Ideally have these in small amounts (about 1/2 cup at once) for help with digestion after they’ve been soaked and sprouted, which helps with nutrient absorption.
- Yogurt and Other Fermented Dairy — Dairy products range in GL scores between about 1–5, with higher-fat types lower in carbs and therefore lower GI. Plain, unsweetened yogurt, raw whole milk and traditionally made cheeses are best (choose organic and raw when possible).
- 100 Percent Whole/Ancient Grains — Depending on the kind, these range between a GL of about 10–17. Choose minimally processed whole grains, such as steel-cut oats, brown rice, wild rice, sprouted grain breads, granola and muesli, and whole-wheat pasta. Moderate serving of healthy complex carbs equate to about 1/2 cup uncooked or 1 cup or less cooked at a time.
- Fresh Fruit — Most fruits have GL values between about 4–14. Fruit can be still be eaten when the rest of your diet is balanced, including stone fruits, apples, berries, cherries and citrus fruits. Fresh fruit is a better choice over fruit juices. Many people can tolerate having about 1–3 servings of fresh fruit daily, especially when they’re active.
- Healthy Fats —All pure fats/oils have a zero GI and GL of zero since they contain no carbs. Good sources include virgin coconut oil, MCT oil, and extra virgin olive oil, along with sources that have slightly more carbs but are still good options like nuts and seeds (like almonds, chia, hemp and flax), and avocado.
- Quality Protein — Animal proteins are also a zero GI/GL food group, containing very little or zero carbs. Choose wild fish, such as salmon, free-range eggs, grass-fed beef or lamb, raw dairy products (including yogurt, kefir or raw cheeses), cage-free eggs, and pasture-raised poultry.
- Acidic Foods — Acidic foods seem to help lower the GI of certain foods. Experts recommend trying vinegar-based dressings on salads, apple cider vinegar taken with a smoothie or water, fermented yogurt with cereal, and lemon juice on vegetables.
- (Healthy Holistic Living Editor’s Note: Garlic -If garlic isn’t already a regular part of your cooking, it should be. Not only is it delicious and aromatic, it’s got a long, long, very long list of health benefits. One of those benefits is that garlic helps maintain and shed unwanted weight. Studies show a direct link between calories burned during daily activities and meals that included garlic that were consumed beforehand. Just remember to brush your teeth right after, or chew some super minty gum. Garlic breath is definitely potent.)The following foods are considered “high-GI food,” which you therefore should try reducing or avoiding:
- Refined grains and flours, including products made with white wheat flour, packaged grain products like most bread, processed breakfast cereals, cookies, cakes, etc.
- Sweetened beverages, such as soda and bottled juices
- Table sugar, honey, molasses, etc. A small amount of real, raw honey can be a good option, but in this case less is usually more.
- Dried fruits, such as raisins, craisins and dates (OK in small amounts, just watch your portion sizes!)
- Starchy root vegetables, such as white potatoes, winter squash, etc. These are actually healthy options, but again portion control and pairing them with lower-GI foods is key.
- Also avoidtoo much caffeine or alcohol
- Empty calories, including packaged goods that are highly processed and salty
- Lots of added sugar in condiments, sauces, etc.
- Fast food and fried foods
Principles of a Low Glycemic Diet
As you can see, the types of carbs included in your diet typically have a big impact on how you feel after eating the food, including how satisfied or full you are, how quickly you get hungry again or experience cravings for more, and how much of a lift in energy the food tends to provide for you. The goal of eating a low glycemic diet is to consume more foods that only have a mild, more prolonged impact on blood sugar since they’re broken down slower and provide more sustained energy.
- Here are several key principles and tips to keep in mind when reducing the glycemic load of your diet:
- Eat carbs that require zero or very little “processing” — One of the biggest factors when it comes to determining a food’s glycemic load/index score is whether it’s eaten in its original state (such as veggies that are raw or mildly cooked) versus whether it’s been processed (like bread, soda and cereal). The more that a food is refined, the quicker its sugar/starch molecules will impact blood sugar. For example, the smaller a starch granule is, the easier and quicker it is for the digestive system to convert it to glucose.
- Get more fiber — Fiber in “whole foods” acts as a protective barrier when it comes to stabilizing blood sugar, slowing down digestion, and protecting sugar and starch molecules from rapid absorption due to enzyme release.The more refined a food is, the less fiber it’s likely to contain. For example, processed grains and sugar supply very little fiber, if any. On the other hand, fresh veggies, fruit, and soaked/sprouted beans or legumes provides lots. Here are some of the best high-fiber foods: artichokes, green leafy vegetables, avocado, cruciferous veggies, chia and flax, and sweet potatoes. (5)
- Make your grains 100 percent unprocessed and ideally soaked/sprouted — Make a habit of reading ingredient labels whenever you eat something that comes in a package or box, such as bread, pasta, cereal or wraps. Look for the words “100 percent whole grain” as the very first ingredient, and check for any indication that sugar has been added, keeping in mind that added sugar can go by dozens of different names. Try to eat foods with just one or very little ingredients, which means they’re more likely to contain natural fiber and less likely to spike blood sugar.
- Get more starch from root veggies — Some people respond poorly to eating grains, especially wheat, which contains the protein called glutenthat can be hard to fully digest. You can get plenty of healthy carbohydrates, fiber and antioxidants too from eating root veggies like sweet potatoes, beets, turnips and winter squash.
- Combine carbs with protein and fat — How you combine different foods is very important when it comes to digestion and blood sugar management. Pairing low GI carbs with a healthy source of fat and protein (such as olive or coconut oil, eggs, and fish, for example) can be helpful for managing blood sugar levels, energy and hunger. (6) Try to include a source of each with each main meal and at least some protein or healthy fat with snacks.
Precautions When Eating a Low Glycemic Diet
If a low glycemic diet seems overwhelming or restrictive, remember that your diet doesn’t have to be complicated to be healthy. Keep things simple by using common sense and choosing source of carbs that are the least processed and contain the fewest added ingredients. Sources of carbohydrates like fruits, ancient whole grains, sweet potatoes, beans, etc., don’t need to be removed from your diet — it’s all about balance and eating real foods!
Follow my recommendation to eat plenty (and a variety of) real foods and avoid fake foods, then you won’t have to pay too much attention to calculating GI scores, calories, grams, etc. Eat foods the way they’re found in nature, listen to your body, and pay attention to your own “biofeedback” and individual symptoms to know what’s best for you.
Final Thoughts on Eating a Low Glycemic Diet
- Glycemic index (GI) and glycemic load (GL) values represent the impact that one average serving size of a carbohydrate food has on your blood sugar levels. Many feel that GL is a more accurate representation compared to GI for determining which carbohydrates are healthy and therefore should be part of a low glycemic diet.
- A low glycemic diet (or low GL diet) has benefits including helping normalize blood sugar, prevent insulin resistance, prevent fatigue, and keep you fuller and energized for longer.
- To start eating a low glycemic diet, follow these tips and recommendations: Get more fiber from veggies, beans, legumes, nuts and seeds; pair foods with higher GL values with proteins and healthy fats; consume 100 percent whole/unprocessed grains; reduce your intake of flour and white refined grains; eat smaller amounts of starchy foods like potatoes, rice and bread; and reduce or avoid sugary foods like cookies, cakes, juices, candy and soft drinks.