High vs Low Glycemic Carbohydrates

Carbohydrates are molecules made up of sugars, starches and cellulose. Carbohydrates primarily provide energy. Glycemic index, commonly known as just G.I., is a term that describes how fast carbohydrates are broken down in the digestive system, forming glucose. Different types of foods containing carbohydrates can be classified as having high or low glycemic index.

The Significance of a Low or High Glycemic Index

When  glucose is released causing blood sugar levels to rise, this signals cells in the pancreas to secrete a hormone called insulin. Insulin facilitates the uptake of glucose from the blood. The glucose is taken up and stored as glycogen by the liver and muscles. This returns blood sugar levels to normal.

When we consume carbohydrates with a low glycemic index, glucose is released more slowly, leading to a steadier rise in blood glucose levels. High glycemic index carbohydrates on the other hand, release glucose at a much faster rate. This signals the pancreas to release higher amounts of insulin. This results in a large drop in blood glucose levels, known as hypoglycemia. Hypoglycemia may cause:

  • Dizziness
  • Weakness
  • Tiredness
  • Shaking muscles
  • Problems concentrating
  • Hungry for more sugar


Examples of Low and High Glycemic Index Carbohydrates

Low G.I.

High G.I.


White bread







Brown rice





Should you avoid all High Glycemic Index Carbohydrates?

While certain foods may have a high glycemic index, they may also be an excellent source of other nutrients. For example, watermelon has a high glycemic index of 72, but it is an excellent source of the phytochemical lycopene. So you shouldn’t avoid all high glycemic index carbohydrates. It is more sensible to have a moderate intake of these. A balanced diet that includes adequate amounts of fiber, fats , protein and low glycemic index carbohydrates will generally lower the impact of high glycemic carbohydrates on blood sugar levels.

At certain times, it may actually be beneficial to eat high glycemic index foods. During exercise blood sugar is used to supply energy to muscles. So after exercise, it is best to have moderate amounts of high glycemic index carbohydrates which release quickly into the blood. This serves to rapidly replenish blood sugar levels and insulin will facilitate the restoration of glycogen levels in the muscles, prevent muscle protein from being broken down and increase the rate of muscle protein production.

Low glycemic Index Carbohydrates and Disease

Low glycemic index foods have been implicated in the prevention of several diseases. These include:

  • Type 2 diabetes
  • Coronary heart disease
  • Obesity

The bottom line is that both low and high glycemic index carbohydrates can be part of a healthy diet. Moderation is the key. Low glycemic index carbohydrates are better in some situations. However, it is also important to keep in mind that high glycemic index foods may also contain nutrients that are necessary as part of a balanced diet. Also, when it comes to situations, such as strenuous exercise, where blood glucose levels need to be replenished quickly, it may be suitable to consume high glycemic index carbohydrates.


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