Carbohydrates are one of three essential nutrient groups necessary for survival. The other two are proteins and fats. Carbohydrates are the primary source of energy for the body. The body converts carbs into glucose, which then enters the bloodstream to fuel the body’s cells.
Not all carbohydrates release energy at the same rate. The Glycemic Index (GI) is a scale that measures how quickly specific foods release glucose into the bloodstream.
Fast-release carbs, or high GI foods, release glucose into the bloodstream rapidly, causing a spike in blood sugar levels. Slow-release, or low GI, carbs foods provide a slower and more sustained release of energy.
This article focuses on some of the slow-release carbs within common food groups. It also provides information on the health benefits of low GI foods, as well as some important considerations when following a low GI diet.
Foods on the GI scale range from 0 to 100, with 0 representing the lowest GI and 100 representing the highest. Pure glucose has a GI of 100.
According to the American Diabetes Association (ADA), low GI foods score less than 55 on the index, medium GI foods score between 56-69, and high GI foods score 70 or above.
A diet that consists primarily of low GI foods can help people maintain blood glucose levels and sustain energy levels.
A low GI diet can also lead to improvements in:
- Weight management: Low GI foods decrease feelings of hunger and increase fat metabolism.
- Cardiovascular health: Improved blood flow due to increased elasticity of the blood vessels.
- Cholesterol levels: High fiber, low GI foods help decrease levels of low-density lipoprotein (LDL), or bad cholesterol.
- Cognitive performance: Slow-release carbs help to sustain energy levels, leading to increased alertness and better cognitive performance.
According to the ADA, many types of breakfast cereals, such as corn flakes, bran flakes, or puffed rice, contain added sugars and are high on the GI scale.
Try replacing these cereals with a slow-release option, such as rolled oats porridge, which has a GI score of 55, according to a detailed list of the glycemic values of a wide variety of foods compiled by the University of Sydney in Australia.
Try serving low GI cereals with other low GI foods, such as unsweetened plant milk, yogurt, nuts, or low GI fruits.
Quinoa is a seed harvested from the goosefoot plant. Quinoa is technically a pseudo-cereal, which is a food that has similar nutrients to grains and requires a similar cooking process.
In addition to a low GI of 53, per 150 gram (g) serving, quinoa is an excellent source of protein and contains a lot of potassium, iron, and vitamin B. It is a particularly nutritious option for people following a gluten-free diet.
Quinoa is a highly versatile food. People can try adding it to salads or soups or making a quinoa porridge to serve with low GI fruits and nuts.
Make sure to rinse quinoa well until the water runs clear to remove the bitter saponin compounds. Pressure cooking is an excellent cooking method for this pseudo-cereal and can help people tolerate it well.
Most vegetables on the glycemic index have a low GI. According to the University of Sydney, examples include:
|Vegetable (per 80g unless otherwise stated)||GI score|
|sweet potato (150g)||44|
Starchy vegetables, such as pumpkin and parsnips, tend to have a higher GI.
The following factors can also affect the GI of vegetables:
- Ripeness and storage: Riper produce has a higher GI.
- Processing: Fresh fruits and vegetables release their carbs more slowly than juiced, mashed, or pureed vegetables.
- Cooking: Different methods of cooking can alter the GI of vegetables. For example, the ADA state that boiled white potatoes have a GI of 74–82, instant mashed potato has a GI of 84–90, and French fries have a GI between 58–68.
Pulses are the harvested beans, peas, or lentils that derive from plants belonging to the Leguminosae or pea family. Most legumes have a GI of 50 or below.
|Legume (per 150g)||GI score|
Legumes also have a high fiber and protein content, both of which help people to feel fuller for longer. They may, therefore, be beneficial in
Legumes also provide a range of important micronutrients, including B vitamins, iron, copper, magnesium, phosphorous, manganese, and zinc.
Nuts and no added sugar nut butters are low in carbohydrates. They are also high in fiber and protein, which increases the amount of time the body takes to digest them. As a result, nuts release their energy slowly without spiking blood glucose levels.
Nuts may be a particularly healthful snack for people with type 2 diabetes. Not only do they have a low GI, but they also contain a high amount of healthful, monounsaturated fats (MUFAs), which may aid blood glucose control and improve cardiovascular health.
For a filling, low GI snack, try spreading almond or peanut butter on low GI fruits, such as sliced apple.
Fresh fruits tend to have a low GI, which raises blood sugar levels at a fairly slow and steady rate. However, tropical fruits tend to have a higher GI.
Examples of low GI fruits include:
|Fruit (per 120g)||GI score|
Examples of fruits with a higher GI include:
|Fruit (per 120 g unless otherwise stated)||GI score|
People who are looking to stabilize their blood sugar levels should opt for low GI fruits wherever possible. When buying canned fruits, avoid those canned in sweetened fruit juices or those containing added sugars. This type of fruit will have a higher GI. Dried fruits also tend to be higher in calories and higher on the GI scale.
Many dairy products, such as milk and yogurt, are low on the GI scale. For example, according to the ADA, whole milk has a GI of 36-42, and a fruit flavored yogurt has a GI of 39–43. Both have a minimal effect on blood glucose levels.
Dairy products are also a good source of protein and calcium. For a low GI breakfast, combine yogurt with low GI fruits and nuts or blend the ingredients with vegetables for a healthful breakfast smoothie.
For vegans and people allergic or sensitive to dairy, soy milk has a GI of 30–38. This makes it a good, low GI alternative.
The ADAlist white bread as having a GI of 73–77. White bread releases its carbs very quickly, causing a significant peak and subsequent crash in blood glucose levels.
To help maintain a healthy blood glucose level, try swapping white bread for one of the following low GI breads:
|Bread (per 30g)||GI score|
|soy and linseed||50|
|sourdough wheat bread||54|
The following factors are also important when attempting to follow a healthful low GI diet:
Smaller meals have less effect on blood glucose levels than larger meals.
The GI of a food describes how it affects blood glucose when eaten alone.
However, combining high and low GI foods in the same meal increases the digestion time of high GI foods. This means they will release glucose into the bloodstream at a steadier rate.
Many high GI foods have a higher nutrient content than low GI foods. People who follow a low GI diet should ideally avoid the low GI foods that offer little nutritional value.
Examples of such foods include:
- chocolate bars
- corn chips
- rice noodles
Following a diet that consists mainly of low GI foods can have a range of health benefits. There are many low GI options to suit a variety of diets and nutritional needs.
When creating a low GI meal plan, consider other factors that can affect blood glucose levels, such as cooking methods, portion sizes, and the ripeness of fresh produce.
It is also important to consider that the GI of a food does not reflect its overall nutritional content. People should aim to eat a variety of foods, especially of nutrient-dense fruits and vegetables, to fulfill their dietary requirements.