Have you read about, or seen on tv, buff stars preaching fat loss benefits of a low 'GI' diet? Or maybe you’ve heard the term 'GI' through a friend and wondered what it’s all about?
Foods like bread, potatoes, rice, pasta, cereal, fruit, soft drinks, alcohol and sweets are all carbohydrates. They are referred to as either simple or complex. Simple carbohydrates are digested fast, while complex carbohydrates are digested more slowly. Another way for describing carbohydrate foods is by the term 'GI' – short for 'Glycemic Index'.
GI also takes into account the rate of digestion of different carbohydrates. More importantly though it considers the speed this digestion causes blood sugar to rise. Some carbohydrates cause fast and sudden rises of blood sugar. Others cause a slow, healthier, and more stable rise in blood sugar.
Many people have happily discovered when they avoid carbohydrates that cause sharp blood sugar rises, and stick to slowly digested carbohydrates instead, they have:
- Better health and cholesterol levels
- Higher and consistent energy
- Less hunger cravings and feel full for longer
- An easier time losing weight and keeping it off
GI is simply a way to rank a carbohydrate food on a scale from 0 -100 based on the speed at which blood sugar rises. The carbohydrates that digest fast and cause sudden blood sugar rises are described as having a High GI. Foods that digest slowly and cause more gradual blood sugar rises are described as having a Low GI. Somewhere in between are the foods described as having a Medium GI. Glucose is used as the reference point and is given a value of 100.
The following shows how this translates into a ‘scoring’ system.
Low GI = 55 or less
Medium GI = 56 to 69
High GI = 70 and above
Many factors can influence GI. Processed foods are usually High GI. Wholegrain and unprocessed foods are generally Low GI. The Fiber content in natural, unprocessed carbohydrates slows down the rate of digestion. This is one factor that can influence GI and why high fibre foods are better choices than refined options where fibre has been removed. A good example is the comparison of fruit juice to fruit in it’s 'complete' natural state. By 'juicing' fruit, health benefitting fibre is broken down and in some cases virtually removed altogether, turning fruit into a high GI sugar rush.
When your body senses increasing blood sugar levels it releases insulin in response. How much depends on how quickly and how high blood sugar levels elevate. Insulins job is to keep blood sugar at 'safe' levels. Over time high blood sugar and the resulting high insulin levels can cause many health problems. Not to mention add Kilo’s of fat to your body.
To make matters worse, if blood sugar is constantly pushed to the limits your body can become resistant to the job insulin is trying to do. When this happens this is called 'insulin resistance', which means the ability of your body to keep blood sugar at a safe level is no longer possible. This condition can lead to many health complications including eventual progression to full blown diabetes.
To keep your body fat levels at healthy or low levels, as well as protect your all round health, choosing lower GI carbohydrates instead of higher GI is the way to go. An important point to remember though is that some processed carbohydrate foods may actually have a Low GI rating due to the content of added fat. Fat in foods can lower GI significantly by slowing down the rate of digestion. So don’t base your carbohydrate choices solely on GI as in some cases, as just described, a Low GI score is not always an indicator of a healthy food choice.
For your reference here's some GI scores of common foods
Clif Bar (Cookies and Cream) 100
White Rice 98
Baked White Potato 95
White Bread 90
Pop Corn 89
Rice Cake 85
Rice Bubbles 81
Corn Flakes 72
Boiled White Potato (Nardine) 70
Sugar (Sucrose) 68
White Rice 64
White Pasta 55
Lite Muesli 54
Whole Brown Rice 50
Wholegrain Bread 47
Wholemeal Pasta 45
Porridge / Rolled Oats 42
Apple (Braeburn) 32