Physical Fitness Alters Glycemic Index

---

The influence of the subjects’ training state on the glycemic index, by S. Mettler and colleagues. Eur J Clin Nutr 61:19-24, 2007

What is the problem and what is known about it so far?

The glycemic index (GI) is a measure of how quickly carbohydrates are digested, absorbed into the bloodstream, and raise blood glucose levels.

The higher the GI number, the more likely a food is to elevate blood glucose quickly.

Some research suggests that there may be more to GI, and that the number can be altered by a person’s physical fitness. According to a group of researchers, being in good physical shape has the effect of lowering GI.

Why did the researchers do this particular study?

The researchers wanted to see whether a person’s level of physical fitness changes the glycemic index of foods.

Who was studied?

Researchers tested 34 subjects, 10 of whom were inactive, 12 were moderately trained, and 12 were endurance trained.

How was the study done?

All subjects ate breakfast cereal with 50 grams of available carbohydrates. Blood tests measured blood glucose levels.

What did the researchers find?

The glycemic index was highest in people who were inactive and lowest in people who were endurance trained. People who were moderately trained had a glycemic index that fell between the other two.

What were the limitations of the study?

The study was small. A larger group of people may lead to different results. Eating breakfast cereal in an experiment may not accurately reflect how people eat in the real world. All of the subjects were male and in good health, and the results may not apply to females or people with medical issues.

What are the implications of the study?

A person’s level of physical fitness appears to affect the glycemic index of foods. More research is needed to understand how important physical fitness is to dietary intake and whether it applies to different groups of people.