HOW COMPLEX ARE YOUR CARBOHYDRATES?
Instead of eating refined carbohydrates, which release their sugar load quickly creating a burst of available energy followed by a lull (and use up the body’s vitamins to break them down), we should be eating unrefined or complex carbohydrates that not only contain more vitamins but also release their energy gradually and consequently result in a more even energy level. This is because their slow digestion means that the sugar they contain trickles into the bloodstream which then transports it to body cells, taking it out of the bloodstream. This results in a ‘flat’ rise to your blood sugar levels, while sugar gives a steep peak in blood sugar level.
The measure of a food’s fast or slow-releasing effect is linked to the degree to which it raises your blood sugar in relation to glucose: the scale is called the glycemic index (or GI) and involves measuring the area under the blood sugar curve produced by glucose. If a food raises blood sugar level significantly, and for some time, the area under the curve is great. Conversely if a food hardly raises blood glucose levels at all, and only for a short time, the area under the curve is small. The biggest curve is created by glucose and is graded as 100 by definition. If a food creates a curve with half the area, it measures ‘50’. Generally speaking it is best to eat foods with a score below 50. The amount of food tested obviously affects how high the blood sugar level will go. Scores given in the chart below are for an average serving of the food in question.
What makes a food fast or slow-releasing depends on more than just the type of sugar in the food. The presence of certain kinds of fiber slows down the release of sugars, so whole foods are much better for you than refined foods. So it is better to eat brown rice, wholegrain bread or whole-wheat pasta than the white stuff. This also means that fresh fruit, which contains the fiber, is better than fruit juices. The presence of protein in a food also lowers its glycemic index. That’s one reason why beans and lentils, both high in protein and fiber, have such a low score.
From a phenomenon first popularized by Barry Sears, author of Enter the Zone, we now know that combining protein-rich foods with slow-releasing carbohydrates further helps to control blood sugar levels. Protein foods tend to invoke a small and equal insulin and glucagon release. Carbohydrates, especially fast-releasing ones, invoke a large insulin release, with little or no glucagon response. Eating fat has little direct effect on either insulin or glucagon. This practice may go against the grain for people familiar with the food combining principles of Dr Hay, who advocated not combining protein-rich foods with starches. Such practice may be very helpful for people with digestive difficulties, but not in controlling blood sugar levels.Generally, foods with a GI score below 50 are great to include in your diet, while those with a score above 70 should be avoided or mixed with a low-scoring food. Those with a score between 50 and 70 should be eaten infrequently and only with a low scoring food. For example, bananas are quite high, with a score of 62. Oat flakes and skimmed milk are low, with a score of 49 and 32 respectively. Having a bowl of oat flakes with skimmed milk and half a banana for breakfast would help to keep your blood sugar level on an even keel, while eating cornflakes (scoring 80) with raisins (scoring 64) would not do that so well.
Some grains are better than others because of the type of carbohydrate they contain. Wheat and corn are high in amylopectin, which makes them fast-releasing. While barley, rye and quinoa are higher in amylose, which makes them slower-releasing. Most rice has a high GI score due to its high amylopectin content. Basmati rice, however, has more amylose and is therefore slower-releasing. Brown basmati is best. One reason why lentils and soy are so low on the GI scale is that they contain a substance which prevents the digestion of amylose, therefore slowing down its release further.
How a food is processed makes a difference too. When wheat is turned into pasta the GI score is low, especially if it is wholemeal. When wheat flour is used to make breads, cakes, biscuits or pastry, the GI score goes up. Therefore whole-wheat pasta is good, while refined white bread is bad. The best bread is whole grain rye bread. There’s a world of difference in the GI effect between this and a French baguette.
Of the grains, oats are among the best. While the GI of wheat varies depending on what’s done to it, oats are the same in any shape or form. Whole oat flakes, rolled oats or oatmeal, as used in oat cakes, all have a low glycemic effect.
THE BEST FRUIT AND VEGETABLES
Most fruits contain fruit sugar, fructose, which is slow-releasing because it first has to be converted to glucose. Some fruits, however, - such as grapes, pineapples, watermelon and bananas - contain not only fructose but varying amounts of fast-releasing glucose. A banana may be fine when you’ve just climbed a mountain and need instant glucose, but it’s certainly not the best daily snack. Half a banana with oats is OK, but oats with chopped apple or pear is better in terms of keeping your blood sugar level even.
Many ‘sugar-free’ foods use grape juice concentrate as a sweetener. This is akin to using glucose. Some use apple juice concentrate which, being high in fructose, is much better.
Almost all vegetables have a negligible effect on blood sugar levels. Those that are worth cutting back on are potatoes, parsnips and swedes which are generally fast releasing (boiled new potatoes are slower); although potato crisps may have a lower score, this is due to the high fat content. The same goes for peanuts.