What is the Glycemic Index? List of Low, Medium & High GI Foods

What is the Glycemic Index A List of Low, Medium & High GI Foods

Have you ever heard of the term ‘Glycemic Index’? Or seen the GI symbol on food products? Here you will learn what the glycemic index is and the difference between high GI and low GI foods


What is the Glycemic Index?

Put simply,

The Glycemic Index (GI) of a food indicates how much eating it affect the glucose (sugar) levels in your blood. It is a way to rate carbohydrates based on how fast it is digested over a period of time (usually a 2 hour period). It also determines whether it provides long lasting energy or not. Pure glucose or white bread (which have a score of 100) are used as references to compare other foods with the same amount of carbohydrate, gram for gram

What is the Glycemic Index A Complete List of Low, Medium & High GI Foods

What is the Glycemic Index A Complete List of Low, Medium & High GI Foods


Difference between Low vs. High GI Foods


High GI Foods

High GI foods (such as sweets, white bread or a baked potato without the skin) break down to glucose quickly, raising your blood sugar & insulin levels rapidly. Because these foods only provide a short burst of energy which is short lasting, you feel hungry sooner. Food that have a GI of more than 70 are considered High GI foods (think high blood sugar levels)

Avoid eating high GI foods (most refined grains & processed foods) because they often lack nutrients and usually contain high levels of added fat, salt & sugar. There are some exceptions though – we will discuss this later

Low GI Foods

Low GI foods (such as oats, beans, most fruit & vegetables) break down to glucose slowly, and gradually release sugar in to the bloodstream over a longer period of time. Because these foods release energy slowly which is long lasting, you feel fuller for longer. Foods with a GI less than 55 are considered Low GI foods (think low but steady blood sugar levels)

Eating low GI foods often provide fiber, B Vitamins, minerals and antioxidants

Any carbohydrate foods that fall somewhere in the middle are classed as Medium GI foods


Watch this video to better your understanding of the ‘Glycemic Index’
Summary of GI Foods from Video:

Low GI: skim milk, plain yogurt, sweet potato, oat bran bread, all bran cereal, parboiled rice, pumpernickel bread, ‘aldente’ or firm pasta (not overcooked), lentils, kidney or baked beans, oranges, plums, apples

Medium GI: bananas, pineapples, raisons, oatmeal, popcorn, split peas, brown rice, couscous, basmati rice, shredded wheat cereal, wholewheat bread, rye bread

High GI: watermelon, instant mashed potatoes, baked white potatoes, parsnips, instant rice, cornflakes, rice crispies, cherrios, bagels, crackers, jelly beans, french fries, soft drinks


Here are some examples of the GI of Different Foods

The foods listed as low, medium and high GI may vary slightly due to different food products & varieties, but these lists give you a general idea of how certain foods rank

What is the Glycemic Index A Complete List of Low, Medium & High GI Foods Examples

Using porridge and corn flakes as an example – porridge is broken down to simple sugars more slowly than cornflakes and provides longer lasting energy


Limitations of the GI Rating System

It is important to know that the GI should not be the only criteria you use when selecting what foods to eat. The Glycemic Index of foods are affected by many different factors, such as how much you eat & what foods you eat them with


The amount of carbohydrates you consume is important too

Also well as taking GI into account, it is also important to watch how much carbohydrates you are eating. For example, even though pasta has a low GI, it is not advisable to have a large serve because the total amount of carbohydrates (and therefore calories) is high

The Glycemic Index does not take into account the amount of carbohydrates, so this is why the Glycemic Load (GL) is also used

The Glycemic Load (GL) is an extension of the Glycemic Index, which takes into account the quantity of carbohydrates in the food portions you eat. For example, eating a high GI food in smaller quantities will have the same effect on blood glucose as having larger quantities of a low GI food. You can work out the the GL by multiplying the GI by the amount of carbs (in grams) in a serving of food

An example: If you compare the GI and GL of watermelon and banana, you will find that even though the watermelon GI (72) is much higher compared to the banana GI (51), the Glycemic Load of 120 grams of banana (13) is over 3 times higher than the GL of 120 grams of watermelon (4)


Combining high GI and low GI foods –  High GI foods are influenced by Low GI foods

Eating low GI foods and High GI foods together will ‘average’ the GI effect it has, which is important to consider because most foods are eaten as part of a meal. Eating cornflakes (which is high GI) and milk (lower GI) for example, will not spike your blood sugar levels as much, compared to if you were to eat cornflakes on their own. Therefore, eating high and low GI foods at the same time can have an affect the GI value of foods


GI does not necessarily make a food ‘good’ or ‘bad’

Also note that not all healthy foods are considered low GI foods, and not all unhealthy foods are considered high GI foods. A watermelon, for example, is actually a high GI food – you wouldn’t want to avoid this fruit just because it is high GI, but you will want to make sure you only eat in small amounts at a time. Another example is that chocolate and corn chips are considered low GI but are high in fat and sugar so are not considered healthy choices


The GI is affected by many other factors too

The glycemic response that a food has is also affected by:

  • Size, texture, viscosity and ripeness eg. unripe banana (30) vs. ripe banana (51)
  • Fat, protein, soluble fiber, fructose and lactose – lower the glycemic response of foods
  • Fat and acid (eg. vinegar, lemon juice or acidic fruit) – slow the rate of digestion & lowers the glycemic response
  • Phytates (eg. in wholegrain breads and cereals) – delay absorption of food & lowers glycemic response
  • Cooking & processing – when food is broken down in to smaller particles it is absorbed quicker & increases the glycemic response

Consuming carbohydrate foods with protein & healthy fats can help to keep you full and give you sustained energy. Eating a balanced meal can therefore improve the effect that carbohydrates have on your blood sugar levels as well


GI is useful for weight loss but is not the only thing to consider

While eating low GI foods can definitely help to control your appetite better, there has been no scientific evidence that a low GI diet is better than a high GI diet. Using GI as a guide can certainly help you eat healthier foods in general, but both the serving size of foods and the nutritional quality should be taken into consideration when planning a healthy diet


Some tips to eat more Low GI foods:

The GI ratings can help you choose healthier food options. Here are some tips to get you started:

  • Switch to high fiber cereals & breads – barley, oats, wheat and bran eg. switch from having cornflakes to oats, and from whitebread to grainy bread
  • Choose grainy crackers as opposed to plain crackers
  • Switch from white jasmine rice to parboiled, basmati or wild rice
  • Include one low GI food at every meal
  • Eat foods high in fiber (including fruit, vegetables, beans and legumes)
  • Consume medium to high GI fruits & vegetables in smaller quantities
  • Eat other foods that contain healthy carbs such as lentils, legumes, pasta, basmati, brown rice & pasta and pita breads
  • Try low GI grains eg. quinoa, buckwheat & barley


Bottom Line:

Eating low GI foods is a good way to ensure you are eating foods that keep your blood glucose levels stable, keep you satiated & provide long lasting energy. You can see why eating these types of foods can help with weight loss & useful if you are active, or an athlete needing sustained energy for exercise. However, it is important to understand the limitations of choosing foods based on their ‘Glycemic Index’ rating. It is important to understand that foods that contain essential nutrients can either be low, medium or high GI but does not mean that you should avoid these foods. Focus on servings sizes rather than just their GI rating as it does not always mean you can eat larger quantities of low GI foods.

In summary, it is not always possible or even necessary to only choose low GI foods. There is definitely room for medium and high GI foods in a healthy diet. Consuming lots of fruits & vegetables (some in moderation), beans and legumes, but smaller portions of potatoes and refined grain products will ensure you have a steady blood glucose levels – helpful for controlling your appetite & weight

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