Information » Diet and lifestyle » Carbs and the Glycemic Index
Although some people don’t pay much attention to what they eat, if you are reading this you are likely not one of them. You know that nutrition is critically important to good health, and it affects how you feel, how you think and ultimately how well you are. This is particularly true about carbohydrates – their effect on your body is more powerful than almost anything else you eat. So it is important to know your carbs.
For decades, people were told that a low-fat diet was the key to optimal health. Unfortunately, this is wrong. At a time when millions of people have struggled to eliminate fat from their diets, an epidemic of obesity has taken on dangerous proportions. That is mostly because people replaced fat with carbohydrates. It comes as a surprise to many people that there is no good scientific evidence that a low-fat diet improves health or promotes weight loss. To read more about this issue, read this article by Gary Taubes in the New York Times.
Dieticians used to separate carbohydrates into starches and sugars, calling them complex and simple carbohydrates. Although these terms are still used by some, they should not be. This is an outdated concept. It is based on structure - sugars are small molecules and starches are big ones.
It is much more useful to classify carbohydrates based on function – what effect they have on the body. This is measured using the glycemic index, which many consider a revolution in nutrition. The glycemic index is a measure of how quickly your body can digest a particular food to turn its carbohydrates into glucose.
The carbohydrates in your food are like beads on a string. The beads are glucose molecules, and they are what your body absorbs and uses for energy. The food you eat is digested in your intestine, separating the glucose beads from the carbohydrate string. That glucose flows into the bloodstream, and this triggers the release of insulin. Insulin shuttles the glucose into the liver and muscle cells, where it can be used for energy.
A food with a high glycemic index is easily digested and enters the bloodstream quickly. This leads to too much insulin being released into the body. Insulin is essential to life, but too much of it does bad things – it promotes fat storage, high blood pressure, high cholesterol, obesity and lots of other chronic diseases of aging – it has been strongly linked to Alzheimer’s disease, cancer and even cataracts.
So it is important to choose low-glycemic index foods. There are many tables and charts on the internet that can tell you which foods are better choices than others. There are many charts you can print, post on your fridge and bring along while shopping for food. Many of these include the glycemic load - which incorporates the amount of carbohydrate in a food as well as how quickly that carbohydrate becomes glucose.
A complete 50-page list of foods was published by Professor Jennie-Brand Miller in the American Journal of Clinical Nutrition. She developed the glycemic index and wrote an excellent book about it called The New Glucose Revolution.
When you become aware of what is good for you and what is not, you will quickly see that it is difficult to be healthy in today’s world because we are surrounded by bad carbs. Here are some of the guidelines I offer my patients:
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