The Glycemic Index

March is National Nutrition Month, so I wanted to touch on something that we often hear about and may not fully understand, but that has a large impact on our health – Glycemic Index.

Glycemic Index defined: a measure of the rate at which an ingested food causes the level of glucose in the blood to rise. In easier terms, Glycemic index is a number from 0 to 100 that gives you an idea about how fast your body converts carbohydrates in a food into glucose, the sugar we use for energy, and how quickly it raises your blood sugar after eating.

As a general rule, a GI rating of:

  • 55 or less is Low (good)

  • 56- 69 is Medium (so-so)

  • 70 or higher is High (bad)

Foods with high GI cause:

  • rapid digestion and absorption, causing a large spike followed by a drop in blood sugar and insulin levels. your pancreas to secrete insulin to bring blood sugar down

  • your body to store excess sugars as fat.

  • a burst of energy/ mood as blood sugar rises, followed by an energy slump, increase in hunger, and some lethargy.

  • those with Diabetes (type I and II) are unable to secrete or process insulin, keeping their blood sugar too high.

Low GI foods cause:

  • slow digestion and absorption

  • a gradual rise in blood sugar and insulin levels.

  • a slower stream of energy, as well as a controlled appetite and delayed hunger.

  • reduced insulin levels and insulin resistance, decreasing the risk of heart disease and chronic diseases.

Clearly, it’s best for our bodies to consume a lower GI diet.

To consume a diet with a lower GI, aim to eat:

  • More whole grains, nuts, legumes, fruits, vegetables without starch, and other foods with a low glycemic index

  • Fewer foods with a high glycemic index, like potatoes, white rice, and white bread

  • Less sugary foods, including candy, cookies, cakes, and sweet drinks

You can bring down the overall glycemic index of your meals by combining a high GI food with foods that have lower GI ratings. So enjoy higher GI foods sparingly, in smaller portions and offset them with low GI foods.

Why does all this matter?

Your body performs at its best when your blood sugar is kept relatively stable and constant. GI can also be a useful tool when it comes to selecting the right types of carbohydrates to consume both before and after exercise.

Studies have showed that a low GI meal/snack pre-workout leads to better maintenance of blood sugar levels during your workout, and a higher rate of fat utilization. This will result in an improved athletic performance.

After a weight training session, regenerating muscle glycogen is a high priority to help aid in muscle repair and growth. That is why, post-workout, you can consume foods with a higher GI. The increase in insulin and glucose from high GI foods after exercise helps facilitate muscle repair. There is a small window of time to consume these higher GI foods post-workout – within 1.5 hours (max). So that doesn't mean that eating cookies and chips five hours after your workout will benefit your muscle synthesis.