Researchers began testing how quickly specific foods like beets and oatmeal convert to glucose (blood sugar), comparing them to white table sugar or white bread. They set a standard measure – how quickly will 50 grams of the particular food’s carbohydrates turn to sugar. That’s called Glycaemic Index (GI).  

What GI doesn’t tell you is how many carbohydrates are in a serving. This presents a problem. For example, you might think a fizzy drink with a GI of 90 is better than cranberry juice because it has a GI of 105 (compared to white bread). You might be tempted to eliminate carrots from your diet due their extremely high GI value (131, using white bread as the base). 

"Do nothing out of selfish ambition or vain conceit, but in humility consider others better than yourselves. Each of you should look not only to your own interests, but also to the interests of others" - Philippians 2:3-4

A More Detailed Explanation
Common sense tells you that a berry-based drink should be better than a sugar-based fizzy drink or that carrots have got to be good for you. That’s where Glycaemic Load (GL) comes in: it takes into consideration a food’s Glycaemic Index as well as the amount of carbohydrates per serving. A carrot has only four grams of carbohydrate. To get 50 grams, you’d have to eat about a pound and a half of them (and who would do that except Bugs Bunny?). GL takes the GI value and multiplies it by the actual number of carbohydrates in a serving. 

131% x 4 = 5

By contrast, a cup of cooked pasta has a GI of 71 and a whopping 40 grams of carbohydrates giving it a GL of 28. 

What Determines GI and GL?
Since the values are based on carbohydrates, the values to a large degree are determined by how many grams there are per serving, and how quickly the carbohydrate is broken down into glucose. Several factors come into play: 

• Amount of cooking: Starches in food swell when cooked (whether it’s boiled, grilled, baked, or fried). The starch grains in a baked potato swell to bursting point, whereas the starch grains in brown rice remain relatively unchanged.

• Amount of processing: When grains are rolled, ground, or smashed, the protective (and harder to digest) outer coating is removed. Whole oats have a lower GI than oatmeal, which is made from smashed oat grains.

• Amount of fibre: Some foods naturally have higher amounts of fibre – for example beans and legumes. Unprocessed foods (for example brown rice) have greater amounts of fibre than processed foods (white rice).

• Amount of fat: The more fat there is in a food the longer it takes to digest. However, too much of the wrong kind of fat has been linked to a number of diseases, including heart disease, diabetes, and obesity.

GL values are interesting – and somewhat useful. But they’re available on a limited basis, and don’t take into account any valuable vitamins and minerals found in a particular food. To be healthy, get sufficient nutrients and fibre, and avoid a blood sugar “spike”: 

• Choose a wide variety of non-starchy vegetables

• Replace refined foods with whole grain products

• Eat fruits and starchy vegetables with high protein and high fibre foods to prevent blood sugar spiking out of control

• Use healthy fats – nuts, seeds, grains, fish, and liquid oils (extra virgin olive oil and pharmaceutical grade fish oil)

• Lose weight (if you’re overweight)

• Exercise regularly

(Willett, W. Eat, Drink, and Be Healthy: The Harvard Medical School Guide to Healthy Eating. Simon & Schuster. 2001)