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A beginner's guide to the low-glycemic diet

Ein Anfänger Ratgeber zur niederglykämischen Diät

The low-glycemic diet, also known as the low-glycemic diet or low-GI diet, is based on the concept of the glycemic index (GI). Studies have shown that the low-glycemic diet can result in weight loss, reduced blood sugar levels and a lower risk of heart disease and type 2 diabetes.

However, the way in which foods are evaluated in this diet has been criticized as unreliable and unable to reflect the overall health effects of these foods.

This article will give you a detailed overview of the low-glycemic diet and describe what it is, how you can follow it and what its advantages and disadvantages are.

What is the glycemic index?

Carbohydrates are found in bread, cereals, fruit, vegetables and dairy products and are also an essential part of a healthy diet. When you eat any type of carbohydrate, it is broken down by your digestive system into simple sugars that enter the bloodstream.

However, not all carbohydrates are the same and different types of carbohydrates have different effects on blood sugar levels. The glycemic index (GI) is a measure that rates foods based on their effect on blood sugar levels. The GI was developed in the early 1980s by Canadian professor Dr. Davis Jenkins (1).

The rates at which different foods raise blood glucose levels are classified in comparison with the absorption of 50 grams of pure glucose, which is used as a reference food that has been assigned a GI score of 100.

There are three broad GI ratings:

  • Low: 55 or less
  • Medium: 56 to 69
  • High: 70 or more.

Foods with a low GI rating are the preferred choice as they are digested and absorbed slowly, causing a slower and lower rise in blood glucose levels. High GI foods, on the other hand, should be limited as they are digested and absorbed quickly, resulting in a rapid rise and subsequent fall in blood glucose levels.

It is important to note that foods are only assigned a GI value if they contain carbohydrates. For this reason, you will not find foods such as meat, poultry, eggs, spices, etc. that do not contain carbohydrates on any GI list.

Factors that influence the GI value of a food

There are a number of factors that can affect the GI value of a food or meal. These include, but are not limited to:

  • The type of sugar: It is a misconception that all types of sugar have the same GI value. The GI value of sugar ranges from 19 for fructose, to 105 for maltose. For this reason, the GI value of a food depends in part on what types of sugar it contains.
  • The structure of starch: Starch is a carbohydrate made up of two molecules: Amylose and amylopectin. Amylose is difficult to digest, while amylopectin is easy to digest. Foods with a higher amylose content will therefore have a lower GI value.
  • How much a carbohydrate has been processed: Different processing methods such as grinding and rolling break apart the amylose and amylopectin molecules, which increases the GI value. In general, the more processed a food is, the higher its GI value (2).
  • Nutrient composition: Both fat and acid slow down the rate at which food is digested and absorbed, resulting in a lower GI value. Adding fat or acid, such as avocado or lemon juice, will lower the GI value of a meal (3, 4).
  • The method of preparation: The method of preparation and cooking can also change the GI. In general, the longer a food is cooked, the faster the sugars contained in the food are digested and absorbed, which increases the GI value.
  • The ripeness of the food: Unripe fruit contains complex carbohydrates that are broken down into simple sugars as the fruit ripens. The riper the fruit, the higher its GI. An unripe banana, for example, has a GI value of 30, while an overripe banana has a GI value of 48 (5).

The amount of carbohydrates is also important

The rate at which food raises blood glucose levels depends on three factors:

  • The type of carbohydrate the food contains
  • The combination of nutrients
  • The amount you eat

However, the GI is a relative measure that does not take into account the amount of food you eat. The GI is often criticized for this reason (1).

To solve this problem, the glycemic load (GL) was developed as an evaluation scheme. Glycemic load is a measure of how a carbohydrate affects blood glucose levels, taking into account both the type (GI) and the amount (grams per serving).

Like GI, glycemic load has three classifications:

  • Low: 10 or less
  • Medium: 11 to 19
  • High: 20 or more

However, GI is still the most important factor to consider when following the low-glycemic diet. The Glycemic Index Foundation, an Australian organization that aims to introduce people to the low-glycemic diet, recommends that people also monitor their glycemic load. It recommends that people should aim to keep their daily glycemic load below 100.

You can find the GI and GL values of many foods in a database( or elsewhere on the internet. Otherwise, the easiest way to aim for a glycemic load below 100 is to choose low GI foods whenever possible and consume them in moderation.

The low-glycemic diet and diabetes

Diabetes is a complex disease that affects millions of people worldwide (6). People who suffer from diabetes are unable to process sugar effectively, which can make it difficult to maintain healthy blood sugar levels. However, good blood sugar control can help prevent or delay complications including heart disease, stroke and damage to the nervous system and kidneys (7, 8).

A number of studies suggest that low-glycemic diets can lower blood glucose levels in people with diabetes (9, 10, 11, 12). A study of almost 3,000 people with diabetes examined the effects of a low-glycemic and a high-glycemic diet on the HbA1c value of the study participants. This value is an average measure of blood glucose levels over the course of the last 3 months (13).

The study showed that HbA1c levels were 6 to 11% lower in subjects following a low-glycemic diet (GI 58 to 79) than in subjects following a high-glycemic diet (GI 86 to 112). In other words, the low-glycemic diet was associated with lower long-term blood glucose levels.

In addition, a number of studies have reported that higher-glycemic diets may increase the risk of type 2 diabetes by 8 to 40% (14, 15, 16). A systematic review of 24 studies reported that the risk of developing type 2 diabetes increased by 8% for every 5 GI points (17).

The low-glycemic diet may also improve pregnancy outcomes in women with gestational diabetes. Gestational diabetes is a specific form of diabetes that can occur during pregnancy. It has been shown that a low-glycemic diet can reduce the risk of macrosomia by 73%. Macrosomia is a condition in which newborns have a birth weight of over 4 kilos. Macrosomia is associated with numerous short-term and long-term complications for both mother and child (18).

Other benefits

Studies have shown that the low-glycemic diet also has other benefits:

  • Improvement in cholesterol levels: low-glycemic diets have been shown to reduce total cholesterol levels by 9.6% and LDL cholesterol levels by 8.6%. LDL cholesterol is associated with an increased risk of heart disease and stroke (10, 20, 21, 22).
  • Supporting weight loss: Low-glycemic diets have helped adults lose between 0.7 and 1.9 kilograms over 5 to 10 weeks. However, the availability of research on the long-term effects on weight loss is limited (19, 23, 24).
  • Potential reduction in cancer risk: People who follow low-glycemic diets have a lower risk of certain types of cancer including endometrial cancer, colorectal cancer and breast cancer compared to people who follow a high-glycemic diet (25, 26, 14).
  • Potential reduction in the risk of heart disease: A review of 37 studies found that people who followed a high-glycemic diet compared to people who followed a low-glycemic diet had a 25% higher risk of developing heart disease. However, more research is needed to prove this link with certainty (14, 27).

Foods you should eat as part of a low-glycemic diet

With the low-glycemic diet, there is no need to control protein, fat or carbohydrate amounts. Instead, a low-glycemic diet involves swapping high-glycemic foods for low-glycemic alternatives.

There are plenty of healthy and nutritious foods to choose from. Your diet should be based on the following low-glycemic foods:

  • Bread: wholemeal bread, rye bread and sourdough varieties
  • Breakfast cereals: porridge made from rolled oats, Bircher muesli and bran cereals
  • Fruit: apples, strawberries, apricots, peaches, plums, pears and kiwis
  • Vegetables: carrots, broccoli, cauliflower, celery, tomatoes and zucchinis
  • Starchy vegetables: Carisma and Nicola potato varieties, sweet potatoes, corn, yams
  • Pulses: Examples are lentils, chickpeas, baked beans, butter beans, kidney beans
  • Noodles: Noodles, soy noodles, vermicelli, rice noodles
  • Rice: basmati, doongara, long grain and brown rice
  • Cereals: quinoa, barley, pearl couscous, buckwheat, green spelt, semolina
  • Dairy products: Milk, cheese, yogurt, pudding, soy milk, almond milk

The following foods contain little or no carbohydrates and therefore have no GI value. These foods can be consumed as part of a low GI diet:

  • Meat: beef, chicken, pork, lamb and eggs
  • Fish and seafood: examples include salmon, trout, tuna, sardines and prawns
  • Nuts: such as almonds, cashews, pistachios, walnuts and macadamia nuts
  • Fats and oils: including olive oil, rice bran oil, butter and margarine
  • Herbs and spices: such as salt, pepper, garlic, basil and dill

Foods to avoid on a low-glycemic diet Nothing is strictly forbidden on a low-glycemic diet. However, you should try to replace the following high-glycemic foods with low-glycemic alternatives as often as possible:

  • Bread: white bread, flatbread, bagels, naan bread, French baguettes
  • Breakfast cereals: oatmeal, rice krispies, cornflakes, cocoa krispies, Froot Loops
  • Starchy vegetables: Désirée and red pontiac potatoes, mashed potatoes
  • Pasta and noodles: Corn noodles and instant noodles
  • Rice: jasmine rice, arborio rice (used in risotto), calrose rice and medium-grain white rice
  • Milk substitutes: rice milk and oat milk
  • Fruit: watermelon
  • Savory snacks: rice crackers, rice cakes, pretzels, corn chips, potato chips
  • Cakes and cookies: scones, donuts, cupcakes, cookies, waffles
  • Other: Jelly beans, licorice, Gatorade, Lucozade

A sample nutrition plan for one week

This sample meal plan shows what a week on a low-glycemic diet might look like. Feel free to customize it based on your own needs and preferences.


  • Breakfast: Oatmeal, milk and sliced fresh fruit
  • Lunch: Chicken sandwich made with whole grain bread, served with a salad
  • Dinner: Roast beef with vegetables, served with long grain rice


  • Breakfast: Wholemeal toast with avocado, tomato and smoked salmon
  • Lunch: Minestrone soup with a slice of wholemeal bread
  • Dinner: Grilled fish with steamed broccoli and green beans

Wednesday: Breakfast

  • Breakfast: Omelette with mushrooms, spinach, tomatoes and cheese
  • Lunch: Salmon, ricotta and quinoa cup with a salad
  • Dinner: Homemade pizza with Lebanese wholemeal bread


  • Breakfast: A smoothie with berries, milk, quark and cinnamon
  • Lunch: Chicken pasta salad made from wholemeal pasta
  • Dinner: Homemade burger with beef and vegetables on a wholemeal bun


  • Breakfast: Quinoa porridge with apple and cinnamon
  • Lunch: Toasted tuna salad sandwich made with whole grain bread
  • Dinner: Chicken and chickpea curry with basmati rice


  • Breakfast: Eggs with smoked salmon and tomatoes on wholemeal toast
  • Lunch: Egg salad and wholemeal wrap
  • Dinner: Grilled lamb chops with vegetables and pumpkin mash


  • Breakfast: Buckwheat pancakes with berries
  • Lunch: Brown rice and tuna salad
  • Dinner: Beef meatballs with vegetables and brown rice

Healthy low-glycemic snacks

If you get hungry between meals, here are a few ideas for healthy low-glycemic snacks:

  • A handful of unsalted nuts
  • A piece of fruit
  • Carrot sticks with hummus
  • A cup of berries or grapes
  • Quark
  • Apple slices with almond butter or peanut butter
  • A hard-boiled egg
  • Leftovers from the previous day's dinner

Disadvantages and shortcomings of the low-glycemic diet

Even though the low-glycemic diet has some advantages, there are also a number of disadvantages and shortcomings. First of all, the glycemic index does not provide a complete nutritional picture of your food intake. It is also important to consider the fat, protein and carbohydrate content of a food regardless of its GI.

For example, the GI value of French fries is 75, while baked potatoes - the healthier alternative - have a higher GI value of 85 (3). In fact, there are many unhealthy low-glycemic foods such as ice cream (GI 36 to 62), chocolate (GI 48) and vanilla cream (GI 29 to 43).

Another disadvantage is that the GI measures the impact of a single food on blood glucose levels. However, most foods are consumed as part of a larger mixed meal, making it difficult to estimate the GI value of the entire meal (28).

Lastly, the GI does not take into account the amount of carbohydrates you eat. However, this is an important factor when it comes to determining their impact on your blood sugar levels. For example, watermelon has a high GI of 80 and would therefore not be considered the best option during a low-glycemic diet. However, watermelons have a low carbohydrate content of only 6 grams of carbohydrates per 100 grams. In fact, a typical serving of melon has a low glycemic load (GL) of around 5 and minimal impact on blood sugar levels.

This all highlights that the use of GI in isolation is not always the best predictor of the impact on blood glucose levels. It is important to also consider the carbohydrate content and glycemic load of the diet.


The low-glycemic diet involves replacing high-glycemic foods with low-glycemic alternatives. It has a number of potential benefits including reducing blood glucose levels, aiding weight loss and reducing the risk of heart disease and type 2 diabetes. However, it also has several disadvantages and shortcomings.

At the end of the day, it is important to maintain a healthy and balanced diet that insists on a wide variety of whole and unprocessed foods regardless of their GI.




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