Some foods can cause your blood sugar spike very quickly. This happens because carbohydrates – such as refined sugars and bread – are easier for your body to change into glucose. (Glucose is the sugar that your body uses for energy). Your body finds more slowly digested carbs – such as those in vegetables and wholegrains – a bit more challenging to turn into glucose. If you eat a lot of those easy carbohydrates you’ll have a difficult time in controlling your blood sugar. The glycemic index (or GI) gives you a way to tell slower-acting “good carbs” from the faster “bad carbs.” You can use it to fine-tune your carb-counting and help keep your blood sugar steadier.
If you eat too many refined carbohydrates, you’ll be constantly eating more and more of these because you’ll find that your energy levels are constantly low. In order for personal trainers to help keep their clients’ energy levels up, and so assist them with getting the most out of their exercise routine, a personal trainer needs to know what types of food are low GI so that they can recommend how their clients should change their diets.
What Is the Glycemic Index?
The GI is a ranking scale of carbohydrates in foods in accordance with how these affect blood glucose levels. As we said earlier in this article, carbohydrates with a low GI value (in other words, 55 or less) are more slowly digested, absorbed as well as metabolised. This means that they cause a lower and slower rise in blood glucose in addition to insulin levels.
There are three groupings of GI:
Individual food portion:
- Low: 55 or less
- Mid: 56 – 69
- High: 70+
There is a very pressing need to define the difference between a low GI diet and/or meal as opposed to a low GI food. As a low GI food is regarded as 55 or less, the entire population has made the reasonable assumption that a diet which averages 55 or less is a low GI diet. The what the average Australian and American eats already has a GI of between 55 and 60 as we eat fruits as well as dairy products. These foods are naturally low GI.
However, in order to reduce our risks of chronic disease, we should be aiming to lower the number of high GI foods that we eat. A GI level of 45 is a better cut-off point:
- Low: 45 or less
- Mid: 46-59
- High: 60+
Why Do We Say 45?
It is known, from numerous global observational cohort studies, that the daily average GI of the diet of people in the lowest 20% of the population is between 40 and 50. An average GI of 45 has been proven to have substantial health benefits in people with existing diabetes and reducing the risk of chronic diseases such as heart disease and diabetes.
Which Foods Are Where on the GI?
Below are examples of foods and where they are on the Glycemic Index:
Low-GI foods Medium-GI foods High-GI foods
rolled/steel-cut oats brown/basmati rice russet potatoes
barley, bulgur couscous white bread
butter beans and peas wholemeal bread cookies
non-starchy vegetables rye bread breakfast cereals
milk quick oats instant pasta
sweet potatoes honey short-grain white rice
The foods that we looked at above are a good place to start if you’re interested in following a low-GI diet. However when you follow this type of diet, remember that high-GI foods are not banned – you should just eat them in moderation.
If you follow a low-GI diet you can also enjoy foods which do not contain carbohydrates, for example:
- olive oil