Blood Sugar Part 1 – The failure of low GI diets

Nutrition, like so many professions, has catchphrases or industry speak. The longer you spend in the field, the more accustomed you become and start to feel like these terms are known and understood by the wider population. Among nutritionists I don’t think there is a bigger catchphrase then ‘balancing blood sugars’. It is a term that gets thrown around and it is assumed that people know what it means. But in honesty I don’t think most people really know what it means. In fact, I think there are a lot of nutritionists that don’t know exactly what it means. So I want to break it down for you and explain it clearly. I am doing this because I think it is a really important concept. Understanding it can help to solve a wide range of problems, things that affect a significant percentage of the population.

When we eat carbohydrates they are broken down into sugars to be used for energy. This sugar is digested and makes its way into your blood. For your body to be able to use this sugar it needs to get into your cells. To help with this process you release a hormone called insulin that comes from your pancreas. Insulin, along with other nutrients, helps the sugar get into the cells where it is needed.

Unfortunately this system does not always work so smoothly and one issue is insulin resistance. The way hormones like insulin work is they’re released into the blood and travel to a receptor site somewhere in the body. Once it gets to the receptor site it docks on to it. The docking onto the receptor site then creates some sort of change or action within the body.

The problem is with the insulin receptor sites. They have become insensitive, meaning that even though there are high amounts of insulin in the blood, the body doesn’t recognise it. This means the sugar is staying in your blood and not getting in your cells where it is needed.

Your blood likes to keep things between a strict range. If the blood sugar is rising but the sugar is not going into the cells it still needs to get the sugar out of the blood supply. If insulin can not put the sugar into your cells for energy then the remaining is converted to fats, causing higher triglycerides (blood fats) and more fat in adipose tissue.

This is how people get into a rollercoaster of using chocolate and quick sugar fixes. They eat food but the energy is not getting to where it is needed in the cells. So they get hungry and eat again.

This condition of poor insulin recognition is called insulin resistance. If it goes on long enough and your blood sugar levels are consistently at high enough levels, you are diagnosed with having diabetes.

So what are the mainstream strategies for balancing blood sugars? The first is advocating a low GI diet (GI means glycaemic index). Foods are ranked based on how quickly they breakdown to sugar and how much of an increase in insulin they cause. The general thinking is that high GI foods, those that break down quickest and cause the highest insulin spike, are unhealthiest. The advice is to eat foods with a low or moderate GI.

This unfortunately doesn’t make much sense for a number of reasons.

Firstly if you have poor insulin receptor functioning, it doesn’t matter whether a food causes a little insulin or lots of insulin to be released, the system is still not working. The sugar is not efficiently getting into the cells and your cells are missing out on their main energy source.

Secondly people with insulin resistance generally have high circulating insulin all the time. The food may increase the insulin, but this increase is rather insignificant against the constant elevated levels. The problem isn’t because the food causes an insulin increase; it is because the levels are constantly elevated. Even on a low GI diet they are elevated.

Both of these reasons are doing nothing about repairing the system, they are just trying to avoid the problem.

The third reason is that the GI tests are done on foods in isolation. To work out the GI of a food a company gets a minimum of 10 people for the study. These people don’t eat anything for 12 hours and then are fed 50g of the particular food (and only that food) after which their blood sugar levels are monitored for 2 hours. This is why when you look at different GI index tables you can have different results because it depends on the people they used to test the foods.

No one eats foods in isolation. Who has just a potato and nothing else? Adding something as simple as butter would change the digestion and absorption rate. What about when this is then combined with a whole meal, with some meat, vegetables and rice? The absorption rate would be totally different. We eat a meal that contains a mix of foods so studying things in isolation doesn’t tell us a lot if we don’t eat our foods like this.

The fourth reason is that foods that have a higher fructose content appear healthier. Fructose is another form of sugar but due to the way it is processed in the body it doesn’t cause an increase in insulin and blood sugars the way that glucose does. This means that Coca Cola is given a rating of 63, making it medium GI, whereas a jacket potato is 85, parsnips are 97 and white rice is 98. According to the index this makes these foods worse for you and things that you should avoid but you can go ahead and drink the Coke.

The fifth reason that the idea doesn’t add up is from looking at populations around the world. Foods like white rice and potatoes are eaten as staples by countries with some of the lowest rates of diabetes and yet they are basically as high as you can get on the GI scale. If rice and root vegetables like potatoes and parsnips as so bad for you, then traditional societies that have lived off these kind of foods should be plagued with diabetes. In fact they are not and have only started to have problems when they adopted more of a Western diet.

For all these reasons I don’t think a low GI diet is the way to go when looking improving blood sugar balance.

In the next post we will look another solution that is recommended for blood sugar balance and the problems it causes. I will also start to give some of my ideas on how you can improve any blood sugar issues you may be having.

You can read part 2 by CLICKING HERE.

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Chris Sandel is the founder of He is a nutritionist, working with clients on a one-on-one basis, as well as creating online trainings and products about health and nutrition. He is the author of The Health Trap: Why "Healthy" Eating Isn't Always Healthy which is available on Amazon UK and Amazon USA.

Chris has three free emails series. One is on how to quit dieting. One is on simple tests you can do at home. And the other is his take on the world's healthiest foods.


  1. Annabel Padgett says:

    Very interesting article, clear and to the point too. Am glad I do not suffer from a sweet tooth or sugar craving. Actually find chocolate unpleasant to eat, disgusting texture when it melts!

  2. Chris Sandel says:

    Hi Annabel. I don’t have a sweet tooth myself but know a lot of people suffer badly with sugar cravings. Sugar can actually be very useful in certain situations and lately I have intentionally be eating more of it lately (things like maple syrup, honey and orange juice) to help with sugar levels. These are issues I will be discussing in the next couple of posts.

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