High GI vs. low GI: what it means for your blood sugar levels

The wonder of AI is that you can type almost anything into ChatGTP and you are immediately an expert on the subject, unfortunately it probably can’t stop you eating that doughnut that you have just been told you probably should leave well alone. Perhaps the following few words might be more successful, though that may depend on how delicious the doughnut looks.

What is glycemic index and why it matters

So, what is glycemic index and why is it important to you and your life?

Glycemic foods are categorised based on their Glycemic Index (GI), which measures how quickly and how much a food raises blood glucose levels after being consumed. The GI scale ranges from 0 to 100, with pure glucose assigned a GI of 100.

Low glycemic foods

- Definition: foods that have a low Glycemic Index (GI ≤ 55)

- Characteristics: these foods cause a slower, more gradual rise in blood glucose levels

- Examples: most fruits (such as apples, oranges, and berries), non-starchy vegetables (such as broccoli, spinach, and carrots), legumes (such as beans and lentils), and whole grains (such as barley and quinoa)

High glycemic foods

- Definition: foods that have a high Glycemic Index (GI ≥ 70)

- Characteristics: these foods cause a rapid spike in blood glucose levels

- Examples: white bread, white rice, potatoes, sugary foods and drinks, and some processed cereals

Medium glycemic food

- Definition: foods that fall in between, with a Glycemic Index of 56 to 69

- Examples: whole wheat bread, brown rice, and sweet potatoes

The role of glycemic index in long-term health

So far so obvious, most of us would correctly guess that a drink of a sugary, fizzy drink will raise our blood sugar more dramatically than a plate of long stem broccoli, but why is it important for our long term health? The answer, as you might suspect, has to do with our metabolic health and what is commonly known as the metabolic syndrome or sometimes insulin resistance. Metabolic syndrome (or MetSyn) is defined in terms of the following five criteria.

High blood pressure
High triglycerides
Low HDL cholesterol
Central adiposity
Elevated fasting glucose

Metabolic syndrome and its relationship with glycemic control

If you unfortunately have three of the above criteria, then you have ‘metabolic syndrome’ and even if you are thin then worryingly you may well not be metabolically healthy. Metabolism is basically the process by which we take in nutrients and break them down for use in our bodies.

How excess sugar affects metabolism and fat storage

So, what happens to that delicious carbohydrate in the doughnut that was mentioned at the beginning of the article? It has two possible fates; it can be converted to glycogen (the storage form of glucose) or it can be stored as fat. The destination is largely decided by insulin and our activity levels. So, an active, elite athlete will likely consume the glucose almost instantly in their muscles, but a more sedentary person, perhaps relaxing in front of the television after consuming said doughnut, will store this as fat.

In some ways that is not such a bad thing, as glucose stored as subcutaneous fat is not such a bad (metabolically speaking) thing. The problem occurs when this metabolic buffer zone is used up (and this capacity will vary from person to person) and the fat starts being stored in muscle, the liver and around other vital organs, this is known as visceral fat and is a whole different metabolic kettle of fish. Individual fat storage varies from person to person and is one of the reasons that a thin person may just have a lower capacity to safely store fat.

Preventing Type 2 diabetes: the benefits of low GI foods

This problem with inappropriate fat deposition is likely to be where insulin resistance starts, where cells (usually muscle cells to begin with) start to ignore the instructions that the insulin is giving them. This leads to higher and higher levels of insulin and also higher levels of circulating glucose and thus the first critical steps toward Type 2 Diabetes have been taken. Sadly, as we are all probably well aware, people with Type 2 Diabetes have a significantly higher risk of cardiovascular disease, as well as cancer and dementia. I remember being told as a medical student that the risk of a person with DM having a heart attack was the same as a person without DM who had already had a heart attack, indeed a sobering statistic.

The idea of the metabolic syndrome and insulin resistance is a useful one, as it can be viewed as a continuum, one that can be stepped off or ideally the direction changed, before the destination of Type 2 Diabetes is reached. So how could choosing low GI foods be helpful in this process? Well in general high GI foods will cause a more rapid and higher spike in blood glucose levels and this will tend to make glycaemic control more difficult and speed up that journey towards insulin resistance and the metabolic syndrome. The high peaks are also often associated as well with a subsequent dip that makes us feel hungrier and overeat later in the day, probably giving into that second doughnut.

It’s not just the type of food we eat that is important, it is how you chew, when you eat and how you prepare it. Chewing slowly a nice crisp apple, or having it quickly as a smoothie will have a vastly different effect on your blood sugar and how full you feel. So perhaps no massive surprises, we probably all knew broccoli was better for us than a chocolate Hobnob, but interesting to see that current scientific thinking completely confirms our ‘GUT’ instinct.

Personalised insights: using DNA testing to manage blood sugar

Now, with the technology available using the MyHealthChecked Glucose Management DNA Test, you can access personalised insights based on your genetic makeup, helping you understand how your body processes carbohydrates and which foods might cause significant blood sugar spikes for you specifically. Our DNA test delivers actionable data unique to your physiology, potentially guiding you to make better food choices and avoid that tempting doughnut more effectively. This personalised approach empowers you to take control of your health, optimising your diet to prevent metabolic syndrome and its associated risks.