The Complete Guide To A Low Glycemic Index Diet

Spikes in blood sugar are bad for weight loss and general health, the low glycemic diet can help you prevent spikes from happening. Have you ever eaten a meal and experienced a sugar crash shortly afterward? You end up feeling tired, hungry, a little irritable, and you might even have a headache that puts a dent in your day.

You can avoid that post-meal crash, improve your metabolic health, and lose weight at the same time by following the low gi diet. It is a diet that promotes fiber-rich food, which keeps you full and in turn makes weight loss easier. A low glycemic index diet (low GI diet) can also reduce fluctuations in your blood sugar and support your overall health.

In this article, we discuss the science behind the diet and how you can use the low glycemic diet for weight loss. We’re also going to tell you about the low GI foods you can eat, and how you can incorporate them into meals without feeling restricted.

What Is The Glycemic Index?

The glycemic index is a measure of how quickly a food containing 50 g of carbohydrates can raise your blood sugar after being eaten. Researchers test different foods by giving study participants portions of food that contain 50 g of carbohydrates and measuring their blood sugar for two hours afterward.

The glycemic index scale goes from 0 to 100, and foods that produce a faster glycemic response (change in blood sugar) have a higher score. Researchers have established that 50 g of pure glucose or 50 g of white bread is used as a reference value of 100.

Foods can be scored as either low, medium, or high-GI foods.

  • Low: ≤55
  • Medium 56-69
  • High ≥ 70

So what is a low glycemic diet exactly? It means eating food that doesn’t spike your blood sugar, or that sits on the low end of the glycemic index.

How Carbohydrates Affect Digestion

Carbohydrates are one of the main macronutrients that we use for nutrition and energy, alongside fats and protein.

We have three main types of carbohydrates in our diets: simple carbohydrates, complex carbohydrates, and fiber. They all differ in how easily they can be digested by the body and how they impact our blood sugar.

Simple carbohydrates are easily broken down into sugar to be used for energy or storage. Because these sugars do not take much time to be broken down, they can quickly enter the bloodstream, cause spikes in blood sugar, and make you feel hungry faster. Examples of foods containing simple sugars include sodas, baked goods, and refined grains.

Complex carbohydrates take longer to be broken down. These carbohydrates are larger and have a complicated structure, requiring more time to be digested. Because it takes longer to digest these complex carbohydrates, the release of sugar in the blood is typically slower without a spike and keeps you full for longer. These carbohydrates are found in starchy vegetables, other fruits and vegetables, and whole grains.

Fiber is considered a type of complex carbohydrate, but we cannot break them down in our small intestine because we lack the enzymes to do so. Instead, our gut bacteria ferment these fibers and use their energy. Because fibers are not absorbed into our bloodstream, they do not cause a blood sugar spike. Examples of fiber found in plant-based foods include pectin, glucomannan, and inulin.

As you can see, low-GI foods tend to take longer to digest, keep you full for longer, and ultimately help prevent the likelihood of overeating.

Apples may be high on the glycemic index but low on glycemic load due to the portion size we normally consume.

Understanding Glycemic Load

While the glycemic index was a measure of how quickly carbohydrates from certain foods could raise blood sugar, the concept of the glycemic load was invented to account for different serving sizes.

Food can be high GI, but the portion size to provide 50 g of carbohydrates may be too large to realistically eat. When you factor in portion size, sometimes a high-GI food may have a lower impact on blood sugar than expected.

Alternately, if you eat a portion of food that has more than 50 g of carbohydrates per serving, it will have a greater impact on your blood sugar. Glycemic load is calculated by multiplying the number of carbohydrates in a serving of a food by its GI, then dividing by 100 (grams of CHO per serving x GI ÷ 100).

Glycemic Load (GL) Categories are as follows:

  1. Low: GL ≤ 10
  2. Medium: GL of 11-19
  3. High: GL ≥ 20

As an example, let’s calculate the glycemic load of an apple. Apples have a GI of 44 and according to the USDA, a medium-sized apple has 25 g of carbohydrates per serving.

Glycemic Load: 25 x 44 ÷ 100 = 11.

Based on the results above, this apple would have a glycemic load of 11, making it a food with a medium glycemic load despite having a low glycemic index.

Glycemic Index Values Explained

Now that you know what glycemic index and what glycemic load mean, and how different carbohydrates affect digestion, it’s time to talk about how these concepts apply to how you eat.

Foods that are low GI or low GL are typically carbohydrate-containing foods that are high in fiber. Fiber helps control the release of sugar into the blood, which in turn increases fullness, decreases sugar cravings, and limits the number of energy spikes and slumps you may experience.

Foods that are low in carbohydrates are also naturally low GI or low GL. Protein foods like meat and seafood, and healthy fats like olive oil are low GI by definition.

It’s important to note that the glycemic index isn’t a perfect measure and should be used as a guide for your food choices. The GI of a food can vary depending on the brand of food, method of cooking, region grown, and more, so you have to pay attention to your foods.

In essence, low GI/GL foods can be considered a subset of the greater variety of foods that keep you full (which is key to losing weight), are nutrient-dense, and offer additional health benefits beyond providing energy.

High Glycemic Index Food Examples

High glycemic foods are usually those that high amounts of sugar and spike your blood sugar. These types of foods give you energy fast and then deplete you of energy quickly too. that makes you hungry and have cravings which can result in overeating of unhealthy foods. Examples of high-GI foods  can be found in the table blow - the values are in averages but give you a good idea of where high GI foods sit on the overall scale of the glycemic index.

Low Glycemic Index Food Examples

Low glycemic foods are broken down slowly by your body which means your blood sugar remains stable and you don’t get hungry fast. That’s because low glycemic foods like fiber, take longer to break down in your body and in turn do not spike your blood sugar. Examples of low-GI foods are provided in the example below and the numbers are in averages but give you a nice glimpse into the difference between high glycemic foods and low glycemic foods. .

What Is A Low GI Diet?

A low-GI diet is a style of eating that is centered on foods that promote satiety and do not cause significant spikes in your blood sugar.  When you eat this way your body naturally ends up regulating how many calories it needs so you can meet your Total Daily Energy Expenditure (TDEE) needs without going over.

Most of your carbohydrate-containing foods should have a low-to-medium GI/GL, meaning that they should contain fiber and not be too processed. A Low-GI diet also includes foods that are naturally low in carbohydrates like lean meats and healthy fats.

Compared to some other diets that restrict carbohydrates, there isn’t a strict limit on how many carbohydrates you can eat daily. Instead, the focus is on choosing carbohydrates that are slowly digested by your body so that you feel full. That can naturally help you reach a calorie deficit which is needed for weight loss.

According to the Glycemic Index Foundation, you should aim to have a total gl\ycemic load of your daily meals at 100 or lower. By following these simple guidelines, you can start to normalize your post-meal blood sugar, feel better after eating and experience some of the additional health benefits of eating low-GI foods.

Foods To Eat On A Low GI Diet

The foods that you can eat on a low-GI diet are typically carbohydrate foods that are high in fiber as well as lean proteins, and healthy fats. These types of foods take your body longer to digest and in turn keep you fuller longer and do not cause your blood sugar to rise rapidly.

Fitmate
Low GI Foods Loe GI Examples 2
 Fish and Seafood Shrimp, catfish, salmon, mahi-mahi, crab, oysters
 Animal Proteins Chicken, turkey, lean red meat, pork, lamb
Legumes Red beans, chickpeas, lentils, black beans, mung beans, black-eyed peas
Nuts and Seeds Almonds, walnuts, pecans, cashews, chia seeds, flaxseed
 Fruit Apples, pears, strawberries, raspberries, blueberries, kiwi
 Vegetables Most non-starchy vegetables, starchy vegetables like winter squash, potatoes like garnet, jewel and sweet varieties
 Whole Grains Oats, bran, rye bread, sourdough
High-Protein Grains Barley, quinoa, pearl couscous, semolina
Unsweetened Dairy Milk, cheese, yogurt
 Healthy Fats Avocado, Olives and plant-based oils

What To Avoid On A Low GI Diet

The foods to be limited or avoided on a low-GI diet are typically foods that are high in simple carbohydrates. You should also strive to choose whole, minimally processed foods when possible.

Some high-GI foods like watermelon or potatoes have a high GI score but can be integrated into a low-GI diet occasionally with proper portion sizes for weight loss.

Fitmate
Foods to Avoid on Low GI Diet Examples of Foods to Avoid
Sugar-Sweetened Beverages Soda, energy drinks, coffee drinks, juice
Refined Grains and Cereals White bread, white rice, refined breakfast cereals, refined pasta
Flour-based Desserts Cookies, pies, donuts, cakes
Processed Snacks Chips, rice crackers, pretzels
Processed Meats Bacon, deli meats
 Fried Foods  French fries, chicken nuggets, 

Benefits Of A Low Glycemic Index Diet

The low-glycemic index diet has many potential benefits to support your metabolic health.

Improves Blood Sugar Control

Low-glycemic diets are an effective way to help individuals control their blood sugar and can even reduce HgbA1c levels in people with diabetes.

A 2019 study compared the effectiveness of low-GI diets to other diet types in people with impaired glucose tolerance, type-1 diabetes, or type-2 diabetes. Researchers found that a low-GI diet was significantly more effective at lowering fasting blood sugar and HgbA1c than people in a generally healthy diet, low-carbohydrate diet, or a heart-healthy diet for high blood pressure.

Another review found similar results – adults with type 1 and 2 diabetes following a low-GI/GL diet had improvements in their HgbA1c, fasting glucose, triglycerides, and other markers. There was a direct relationship between lower GL and improvements in HgbA1c.

Improves Appetite Control

Because the low-glycemic index diet consists of many foods that are high in fiber and reduce spikes in blood sugar, it has the potential to improve appetite control and maintain weight loss.

For example, the PREVIEW trial was a 3-year, multinational diabetes prevention project for people with prediabetes. After an 8-week weight-loss trial, participants were assigned to different glycemic-index and exercise groups for a 148-week long weight loss maintenance phase.

People who were on a high protein, low-GI diet had decreases in hunger ratings compared to those following a medium-protein, medium-GI diet. Neither group was significantly different in weight regained during the trial.

Available research examining the benefits of a low-glycemic diet is still somewhat limited, and researchers note that many studies on low-GI diets and appetite are of poor quality.

Improves Cholesterol

A low-GI diet can be effective alone or combined with other dietary changes to improve cholesterol.

A 5-week trial concerning the beneficial effects of a low-GI diet on weight and cardiovascular risk compared an intervention diet containing low-GI starches to a diet with high-GI starches. In the low-GI group, participants experienced greater weight loss, a trend towards decreased hunger sensation, and a significant reduction in total and LDL cholesterol compared to the high-GI group.

In a study published in 2021, participants followed a reduced-calorie, fat-restricted low-GI diet for 3 months with additional guidance and support. By the end of the trial, participants had significant reductions in their cholesterol, triglycerides, weight, BMI, waist circumference, hip-to-waist ratio, visceral fat, and body fat percentage.

Drawbacks Of A Low GI Diet

The main drawback to the low-GI diet is that while the low-GI diet promotes high-fiber foods, it does not cover all of the key pillars required to lose weight. The diet does not talk about eating enough protein to keep you full, eating fats in moderation, or maintaining a calorie deficit to lose weight.

Here are some additional drawbacks to this diet that you should consider:

Bacon is Low GI, even though it's not a super healthy thing to consume.

Low GI Does Not Always Mean Healthy

Though lower-GI foods tend to be higher in fiber, complex carbs, and other nutrients, this is not always the case.

If you’re only focusing on eating low-GI foods, you could miss out on healthy foods like sweet potatoes, which are high in vitamin A, B vitamins, and vitamin C. Many whole-grain foods and some fruits also fall under the category of medium-to-high GI, yet they have multiple benefits for our bodies.

It is also possible to lose weight while having a moderate amount of high-GI foods including your favorite comfort foods.

On the other hand, some unhealthy foods can have a low GI score. Examples of unhealthy low GI foods include processed meats like bacon or instant pudding.

The point of a low-GI diet is not to avoid carbs altogether but to limit refined carbs like scones and cookies, and promote complex carbs rich in fiber to keep you full like beans, oats, and apples.

What ultimately matters is creating a calorie deficit while eating foods that are filling. If most of your foods are filling, then there is room for eating some high-GI foods while maintaining the benefits of a low-GI diet.

GI Database Of Food Is Limited

The official database for the GI and GL content of food is the International Glycemic Index Database, hosted by the University of Sydney. The foods included on this list are from hundreds of studies from researchers across the globe and this list contains some branded and generic foods.

Unfortunately, this list is quite limited. It currently features approximately 2100 different items from global research, and many items are region-specific. Beyond this, there were many foods that I could not find on this database including vegetables like broccoli, grits or polenta, satsumas, and other foods.

In an article recently published in November 2021, the official list for the glycemic index database has grown over 60% since it was last updated in 2008 and will contain over 4,000 food items. Newly added foods include dragon fruit, whole tomatoes, some gluten-free products, and different varieties of barley and dates.

These changes have not yet been made to the official website, but will likely be coming soon. In the meantime, it may be difficult for people following a low-GI diet to get accurate information on the GI of specific foods.

Losing Weight On A Low GI Diet

It is possible to lose weight on a low-GI diet. By choosing foods that are filling and don’t trigger sugar cravings, you’re already on the first steps towards a healthy low glycemic index diet for weight loss.

Read on to learn how the above drawbacks of the low-GI diet are addressed in our recommendations below to make losing weight on a low-GI diet easier.

Track Your Calories

The standard practice for losing weight is to keep track of your calories and create a “calorie deficit.”

Creating a deficit requires setting a target calorie that creates a deficit between your activity level and how much you eat. To lose 1-2 lbs per week, experts generally recommend reducing calorie intake by 500-1000 calories/day. Remember, calorie goals should be realistic to provide your body with the calories it needs to function properly.

The most sustainable way to make calorie tracking work is to have a diet composed of filling foods. Eating filling foods (like those with fiber, protein, and healthy fats) makes it possible to stick within a calorie range without feeling too hungry.

It is still possible to lose weight while having some high-GI comfort foods. You can create a daily calorie deficit in your meals while eating foods that you enjoy, regardless of GI.

Plan Your Meals For Success

It's more important to keep focused on what keeps you full (and limit what doesn’t) than to obsess over getting meals with the lowest GI scores possible.

Instead of spending all of your energy avoiding every non-low GI/GL food religiously, focus on getting the trifecta for fullness: protein, fiber, and a small number of healthy fats.

An example of a great low-GI lunch has a healthy protein like salmon or tofu, fiber from green leafy vegetables and additional vegetables for extra taste and fiber, and some healthy fats like avocado to keep you satisfied.

If you have a fruit with medium-to-high GI or GL at the end of the meal, it’s okay. The overall composition of the meal can stabilize your blood sugar, especially if you focus on your proteins and fats first.

For the best GI/GL composition, you can focus on berries and stone fruits that are lower-GI and higher in fiber over tropical fruits. Still, this is an extra benefit rather than the main focus. Choose foods that taste good and help you feel full.

Work With A Health Coach

A weight loss coach can not only show you how to switch to eating low GI/GL foods but also how to incorporate a low-GI diet into all the other key things necessary to lose weight:

  • Choosing nutrient-dense foods that keep you full
  • Eating healthy fats in moderation
  • Prioritizing protein intake to stay full
  • Creating a calorie deficit between diet and exercise
  • Engaging in regular physical activity to support fitness and positive changes in body composition
  • Practicing lifestyle habits that reduce stress and improve sleep quality

If you’re ready to start your path to wellness and want a knowledgeable guide at your side, take the Fitmate Quiz. The quiz will determine your unique fitness profile and match you with a weight loss coach that understands your needs.  

FAQ

Is a low glycemic diet the same as keto?

A low-glycemic diet is not the same as keto. Keto is a diet that is high in healthy fats, moderate in protein, and very low in carbohydrates (usually 5-10% total calorie intake) that puts your body into a state of ketosis. On a low glycemic-index diet, there are no strict macronutrient requirements, and the focus is on choosing foods that stabilize your blood sugar and promote satiety.

How do I start a low GI diet?

Starting a low-GI diet can be easy. Try eating meals that contain lean proteins, vegetables, and healthy fats, with fruit as a dessert. Foods that are high in fiber will typically be low-GI, so focus on getting more of those foods into your diet.

Are slow carbs low glycemic?

Slow carbs are carbohydrate-containing foods that are digested slowly in the body, provide sustained energy, and don’t rapidly raise your blood sugar. In essence, they are low-glycemic carbs with a different name.

What is the glycemic load of a meal?

The glycemic load of a meal is the sum of all of the foods on your plate. Glycemic load (GL) is calculated by multiplying the carbs in a serving of food by its GI, then dividing by 100 (grams of CHO per serving x GI ÷ 100). To figure out the total glycemic load of your meal, add up the GL numbers from each food.