We have a handy spreadsheet file that provides you with a database of common foods and their Glycemic Index.
The glycemic index (GI) is a value used to measure how much specific foods increase blood sugar levels. This is normally in comparison to glucose, which would be seen to 100% glucose in the bloodstream and thus have a value of 100.
Foods are classified as low, medium, or high glycemic foods and ranked on a scale of 0–100.
Foods are generally classified as Low, Medium and High GI:
- Low: 55 or less
- Medium: 56–69
- High: 70 or above
Foods high in refined carbohydrates and sugar are digested more quickly and often have a high GI, while foods high in protein, fat, or fiber typically have a lower GI value. Foods that contain no carbs are not assigned a GI and include meat, fish, poultry, nuts, seeds, herbs, spices, and oils.
Other factors that affect the GI of a food include the ripeness, cooking method, type of sugar it contains, and amount of processing it has undergone.
When we combine the Glycemic Index (GI) of a food with its Glycemic Load (GL) we are able to tell how much certain foods are spiking our blood sugar level. Glycemic Load is basically the amount of glycemic carbohydrate in a food that you actually consume. To illustrate how GL changes things, a food like watermelon has a high GI but there is very little of this high glycemic carbohydrate as watermelon is around 93% water. Therefore, watermelon tends not to be regarded as especially unhealthy for diabetics provided they do not eat too much of it. In general, though, GI alone is a great predictor of blood glucose reactions.
During digestion, foods that contain carbohydrates are converted into glucose. Most of this glucose is sent into your bloodstream, causing a rise in blood glucose levels. This increase in blood glucose signals your pancreas to produce insulin, which tells cells throughout your body to take in glucose from your bloodstream. As the glucose moves into your cells, your blood glucose levels go down. Some cells use the glucose as energy. Other cells, such as in your liver and muscles, store any excess glucose as a substance called glycogen, which your body uses as a fuel source during exercise and between meals. When our blood sugar spikes rapidly then much insulin is released by the body and this places us at risk of a kind if desensitization that can occur where your cells do not respond to these floods of insulin the way they used to. This is called Type II diabetes, and over time your body produces less insulin and the problem worsens.
Diabetes in turn correlates with a number of other chronic illnesses including more recently where it has been linked to a host of neurological conditions.