by Chad Rhoden MD PhD

Created on: January 09, 2008

What is the truth about carbohydrates? A very popular question asked by someone interested in making diet changes is, "What about "low-carb" diets?" Well, the truth is, carbohydrates may be the most "pesky" of the three major types of foods. The hype surrounding the low-carb craze certainly has a basis, although this concept may not always describe the entire picture. It is important to define the types of carbohydrates clearly. Secondly, there are a variety of "low-carb" diets that are recommended for different reasons (Atkins, Protein Power, Sugarbusters, The Zone are generally for weight loss and not for long-term use). Be careful to avoid low carb diets that suggest eating excessive amounts of fat (especially saturated). Think about it this way- "How could eating all of the sausage, bacon, and steak you want and at every meal possibly be healthy for your body in the long run with all we know about the dangers of excess fat?

In general, so-called refined carbohydrates are not good in excess. Refined carbohydrates (i.e. white bread, white rice, white pasta, most crackers, sweets, jams, and jellies) increase blood sugar levels. These foods have fewer relative nutrients than unrefined counterparts, thus earning the name "empty calories". By reducing these types of carbohydrates, the blood sugar and insulin levels can be better controlled. This is crucial to persons who are diabetic and is also very important for weight maintenance in healthy individuals. My recommendation is not to eliminate carbohydrates from the diet, but eat the "right" ones! Go ahead and eat carbohydrates in fruits, vegetables, and whole grains (i.e. brown rice, whole grain cereals, stoned ground whole grain bread, whole wheat pasta, etc.). There are many benefits such as energy and fiber found naturally in many of these products, and they are often enriched with vitamins and minerals as well. I recommend at least some familiarity with the glycemic index (GI), which is a measure of how quickly blood sugar rises when you eat particular foods. Low GI foods have a small impact on blood sugar and include most whole grains and vegetables, along with many fruits. On the other hand, high GI foods raise blood sugar more quickly (i.e. white, processed grains/starches, juices, desserts, candy, soda).
So why is all of this blood sugar level stuff of any importance to us? Well, a rapid rise in blood sugar levels results in higher levels of a naturally produced hormone known as insulin. Insulin causes hunger by basically moving sugar from your blood into your cells to either used as energy in needed or otherwise stored as fat. This may be different for those such as marathon runners and others who do a large volume of aerobic exercise training. To compound this issue, these foods also cause less satisfaction and fullness because the blood sugar disappears more quickly (i.e. it's turned into fat and not available for the body to use readily). This then generally leads to overeating and higher caloric intake, resulting in weight gain, which is typically not desired by most of us, either! The reality is, however, that high GI foods make up the majority of carbohydrates in the average American diet. We will talk more specifically about weight loss a bit later, but I wanted to give some mention of it here for context. GI values can be interpreted intuitively as percentages on an absolute scale and are commonly interpreted as follows:

Classification GI range Examples
Low GI 55 or less Most fruit and vegetables (except potatoes), whole grains, rice, pasta
Medium GI 56 - 69 Sucrose, candy bar, croissant, some brown rices
High GI 70 or more Corn flakes, baked potato, some white rices (e.g. jasmine), white bread

Learn more about this author, Chad Rhoden MD PhD.
Click here to send this author comments or questions.