Peaks and troughs

A few people have asked me what the glycemic index is, so I thought I’d write this short post. I take a look at who developed it, what it is, why it matters to you and I give examples of low and high GI foods. Just remember what Julieanna Hever says in The Complete Idiot’s Guide to Plant-Based Nutrition:

“Ultimately, a whole food, plant-based diet optimizes blood sugar, so you don’t need to be overly concerned with measurement tools such as the glycemic index and glycemic load. Just enjoy whole-plant foods, and you’ll never have to count, measure or weigh again!”

Who developed it?

It was developed at the University of Toronto by Dr David Jenkins, however more recently Jennie Brand-Miller at the University of Sydney, has expanded it.

What’s the point of it?

It helps us to understand how quickly a particular food releases sugar into our bloodstream. This means we can compare different foods and choose the ones best for us.

For people suffering from diabetes the key is about holding their blood sugar steady and giving them the nutrition that they need without having huge spikes that high GI food can cause.

Various factors have to be taken into consideration such as:

  • how ripe the food is
  • how it’s prepared
  • measurements are performed on single items and so it will change when eaten with other foods
  • different people respond in different ways to different foods

So what is the glycemic index (GI)?

The definition of the glycemic index comes from the University of Sydney:

“It’s a ranking of carbohydrates on a scale from 0 to 100 according to the extent to which they raise blood sugar levels after eating.

 Foods with a high GI are those which are rapidly digested and absorbed and result in marked fluctuations in blood sugar levels.

 Low-GI foods, by virtue of their slow digestion and absorption, produce gradual rises in blood sugar and insulin levels, and have proven benefits for health. 

 Low GI diets have been shown to improve both glucose and lipid levels in people with diabetes (type 1 and type 2). They have benefits for weight control because they help control appetite and delay hunger.

 Low GI diets also reduce insulin levels and insulin resistance.”

Why will this help me?

A study in 2011[1] showed “that individuals who followed a low-GI diet over many years were at a significantly lower risk for developing both type 2 diabetes, coronary heart disease, and age-related macular degeneration than others.”

Ideally you’re looking for food that passes into your blood slowly, low GI foods help control blood sugar, so that’s food with a GI of 55 or less. Foods that are 70 and above have a high GI.

A basic rule of thumb is: keep it whole food, plant based, low in fat and low GI.

Examples of low GI food are:

  • Fruit, except for watermelon and pineapple
  • Beans, peas, lentils
  • Green vegetables
  • Barley, bulgur, par boiled rice
  • Pumpernickel, rye
  • Pasta

Examples of high GI food include:

  • Sugar
  • White and wheat breads choose rye or pumpernickel instead
  • White potatoes – choose yams or sweet potatoes instead
  • Most cold cereals – choose oatmeal or bran cereals instead
  • Pineapple, watermelon

The basic rules are:

As the Physicians Committee for Responsible Medicine (PCRM) states:

  1. Avoid animal products
  2. Keep it low in fat by avoiding margarine, butter, oils and oil salad dressings, and large quantities of nuts
  3. Choose low-glycemic index carbohydrates which tend to stabilise blood sugar levels, unlike more processed carbs, such as white sugar and white flour. Know that all carbohydrates are not created equal! Old fashioned oatmeal, sweet potatoes, rye bread, tortillas, brown rice, most fruits and all non-starchy vegetables have a low-glycemic index.
  4. Choose high-fibre foods

To read more about the glycemic index and reversing diabetes I’d recommend Dr Neal Barnard’s Program for Reversing Diabetes book.

Why this matters to you

If you’re still wondering if this matters to you, Jennie Brand-Miller, PhD, of the University of Sydney combined the results of 14 studies on the glycemic index that included 356 participants. She found that choosing low-GI foods reduces haemoglobin A1c by 0.3 to 0.4 percentage points. Studies have shown a similar benefit for both type 1 and type 2 diabetes.

To find out more about the GI of the food you love, or the Glycemic Index in more detail, head over to:

Here’s a link to other diabetes calculators that you may find useful:

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Up above, I shared with you What is the glycemic index? If you found this post helpful, please take a moment to SHARE this post with people you think will find it valuable. You can use the buttons to share this post with your social networks. Hopefully you will and so I’ll give you a big THANK YOU in anticipation.

What do you think? Have you heard of it? Do you use it? Let me know below.


If you suffer from diabetes remember to work closely with your doctor/nurse. A diet change can alter your need for medication and have other effects.

Check blood sugar levels as directed by your healthcare provider. Healthful diet changes often cause blood sugar levels to fall.

[1] Chiu CJ, Liu S, Willett WC, et al. (April 2011). “Informing food choices and health outcomes by use of the dietary glycemic index”. Nutr. Rev. 69 (4): 231–42. doi:10.1111/j.1753-4887.2011.00382.x. PMC 3070918. PMID 21457267.