The Truth About Carbs

Not all carbohydrates are the same!

People with diabetes are advised to choose starchy carbohydrate foods - such as bread or potatoes - in preference to sugary foods, as starchy food would raise their blood glucose more slowly. So it can come as a surprise to find that, when you test your levels, some starchy foods raise your blood glucose almost as quickly as sugar.

A good example would be white bread. If you eat white bread it can raise your blood glucose just as quickly as eating simple sugar and more quickly than, for example, chocolate!

So is this advice wrong? Well not completely, but the situation is more complicated than was first thought. Read on to find out how by choosing your carbohydrate foods carefully you could improve your blood glucose levels.

How carbohydrates differ

The carbohydrate in the food you eat is digested by breaking it down into glucose, which your body uses for fuel. The speed at which you carry out this digestion depends upon three factors:

1. The type of carbohydrate
   It appears that the speed a starchy carbohydrate food is digested depends upon its structure. Carbohydrates are made up primarily of glucose molecules linked together into two main types of structure: amylopectins, where the links have lots of branches; and amylose, where the molecules are linked in long straight chains. The more long straight amylose chains there are in a carbohydrate, the more resistant it will be to digestion, so the longer it will be before the glucose molecules reach your blood.
2. The other constituents in the food
   Other constituents in a food can alter the rate it is digested and absorbed. Chocolate, for example, while full of sugar, also contains considerable amounts of other carbohydrates as well as protein and fat. The consequence is that the effect of chocolate on your blood glucose is not as dramatic as you might expect.
3. The other foods that are eaten at the same time
   In the real world we seldom eat single foods in isolation; generally they are part of a meal containing not only carbohydrate but also a mixture of fats, protein and fiber. All these constituents can slow the absorption of the carbohydrate.

Ranking carbohydrate foods

To untangle this complexity, carbohydrate foods have now been ranked according to how rapidly they affect your blood sugar levels. An index has been invented, called the Glycemic Index (GI), which places them on a scale of 0 to 100.

Glucose or white bread is given the index 100; other foods are ranked against this.

• Foods with a high GI are quickly digested and absorbed and can rapidly raise your blood glucose.
• Foods with a low GI are slowly digested and absorbed and so raise your blood glucose more gradually.

As the following table shows the effect of some foods can be surprising:

Benefits of slow acting carbohydrate

• Meals with a low GI can give you a smoother level of blood glucose through the day, avoiding hypoglycemia and also preventing blood glucose from rising too high.
• Low GI foods can help with weight loss as they make you feel fuller for longer so you eat less.
• Some research has shown that low GI diets may lower your risk of heart disease.

Eating a low GI diet

Choosing a low GI diet is a bit more complicated than just looking up the index in a book - although there are plenty of books available. Don't forget that the GI level is for a food eaten alone and we tend to eat foods in groups, as a meal. Even the method of cooking you use can affect the GI.

To get started, here are a few simple tips:

• Try including low GI foods in every meal; they can slow the absorption of the other food.
• Choose the main carbohydrate in your meal carefully and add lots of vegetables. Remember pasta, for example, has a lower GI than bread or potatoes.
• Avoid chocolate and nuts as snacks if you are trying to lose weight; they may have a relatively low GI but they contain lots of calories!

Try a few experiments with your favorite meals. Test to see how much they raise your blood glucose, then try substituting some of the ingredients with lower GI equivalents next time around and see if your glucose levels improve after you have eaten.

Watch out for hypoglycemia as your treatment requirements may change.

Finding out more

Low GI diets are becoming increasingly popular and there is an ever-growing number of books on the subject.  In these books the low GI diet is mainly being described as a weight reduction program but many contain useful information, plus tables of the main low GI foods to help you put together your diet plan.

There are several places on the internet where you can purchase such books (Amazon is one example).

 

Important Notice: Information provided is for general background purposes and is not intended as a substitute for medical diagnosis or treatment by a trained professional. You should always consult your physician about any health care questions you may have, especially before trying a new medication, diet, fitness program, or approach to health care issues.

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