Understanding your glycemic index

The glycemic index was first developed 25 years ago by a professor of nutrition to help determine which carbohydrate foods were best for people with diabetes.

Carbohydrates are vital in the diet, but the problem with modern carbohydrates is that they can be overly processed and nutrient deficient.

All carbohydrates are made up of sugars. There are a number of different types of sugars but in the body, all carbohydrate metabolism converts sugar to glucose, our body’s preferred energy source. Glucose is the main sugar present in many foods but some contain different sugars, such as fructose in fruit and lactose in milk. Most sugars are digested and absorbed and converted to glucose, some cannot be digested, we call this fibre.

The GI rating is based on the sugar response during digestion, high GI meals release sugar (glucose) rapidly, This will lead to high blood sugar levels and higher levels of insulin, more chance of storing calories as fat, and more chance of hunger pangs soon after eating. Low GI foods or meals, on the other hand, are digested much slower, blood sugar and insulin levels are kept on a steadier curve, and weight loss is much easier.

Here are a few pointers on how you can make the GI index work for you:

  • The ratings can be confusing, as many high-fat foods like a Snickers bar are low GI, this is because the addition of fat slows down digestion. Don’t be fooled by this as you’ll end up consuming too many calories! You should be aiming to eat low-fat foods, and the little fat you do eat should be from natural healthy fats, don’t forget fat is hidden in most of our foods even lean meat, so getting our fat intake for the day is easy, we shouldn’t need to add any.
  • Experts warn against using glycemic index alone when choosing foods because it does not account for serving size, the effect of eating different foods together in one meal, which is how most people eat. For this reason, we suggest that a more important measure is the “glycemic load,” which adjusts the glycemic index for serving size. (Multiply glycemic index by the number of carbs per serving and divide by 100.) The glycemic load provides a better idea of sugar levels.
  • Wholemeal bread can have a just as high glycemic index as white bread! The reason for this is that the grains are so fine, they digest as fast as white bread. Choose wholegrain bread, the nuttier and grainier the better.
  • Use the GI as a guide only, the amount of food you eat in a day is most important, but by following the low GI guidelines, you’ll be choosing quality carbohydrates.
  • Don’t be scared to eat high GI foods, as the overall GI of the meal will be lowered if only a percentage of the meal comes from High GI foods.
  • Adding lemon juice or red wine vinegar to a meal reduces the GI of the meal! (so vinegar on your chips isn’t such a bad idea).
  • The best time to eat high glycemic foods is straight after exercise! Your body will need carbohydrates quickly after training. Before training use low GI foods about an hour prior, for sustained energy.
  • If you select your food based on the glycemic index (GI) alone, then you would have little guilt eating a chocolate bar, while watermelon would be forbidden. But when you account for carbohydrates per serving, watermelon’s glycemic load (GL) is much lower, and much preferred than the chocolate.

Type 2 diabetes and obesity are a real problem in New Zealand, many people believe education is the key, however, we think there is information overload regarding nutrition, and with all the fads and new information the average person becomes confused, and typically doesn’t know where to start. The best option is to see Nutritionist, who can help with goal setting and take an individual approach to help you get where you want to be. Remember it takes years to develop a disease like type 2 diabetes or be obese, so it is realistic to spend at least 3-6 months to change lifestyle and nutritional habits.

You can pick up a GI rating index from your local bookstore or online.