I often get questions about glycemic index- what is it, how it works, and why are there so many diet books about it?

Quick Anatomy Lesson:

Whenever a food or beverage is ingested, our bodies respond with a routine chain of events. Complex nutrients get broken down into the simplest form of energy the body can use (glucose or "blood sugar"). Though digestion is routine, what varies is how severely and how quickly the ingested item causes blood sugar to rise.

For the average person deciding what to cook for dinner tonight, considering the effect of a particular food on blood sugar is too time consuming. Well, insert the concept of glycemic index (GI) and glycemic load (GL) and the guesswork is gone...right? Not so fast.


Glycemic Index (GI)-Measures the body's response to a particular food in terms of what effect the food has on blood sugar. In general, "high GI" foods are less desirable because they spike blood sugar while "low GI" foods have a more moderate effect on blood sugar, causing a lower and slower rise overall.

  • Scores of 70 and above are considered high glycemic index
  • Scores of 55 or below have a low glycemic index
  • Check out Harvard's GIpage for more info

Glycemic Load (GL)-

  • 20 or more is high,
  • 11 to 19 is medium
  • 10 or under is low

First of all, associating a food with a number takes the pleasure out of eating. The goal of eating is to fuel the body, not require critical thinking. Furthermore, research continues to show variability between subjects and within subjects when it comes to the body's response to given foods. In other words, no two people are the same and even the same person can respond to the exact same food differently on different days.

That said, there are valuable lessons to be learned if you're interested in hopping on the GI train. The concept can be used as a learning tool to understand complex versus simpler carbohydrates. Use it as a guide for understanding how certain foods typically affect the body. Beyond that, stick to the basics presented weekly in this blog. Isn't it easier to learn general rules?

Tanya Zuckerbrot, MS, RD is a nutritionist and founder of www.Skinnyandthecity.com. She is also the creator of The F-Factor DietaC/, an innovative nutritional program she has used for more than ten years to provide hundreds of her clients with all the tools they need to achieve easy weight loss and maintenance, improved health and well-being. For more information log onto www.FFactorDiet.com.