Glycaemic Index (GI) is a ranking of carbohydrate foods according to the rate they are digested and increase blood glucose levels. Simply speaking, all carbohydrates are broken down to glucose in the body. The GI of pure glucose is 100. Low GI (<55) raises blood glucose levels slowly. Medium GI (55-69) raises blood glucose levels a bit faster. High GI (>70) raises blood glucose levels most rapidly.
GI is affected by the type of carbohydrate, fat content, ripeness, how it was cooked and fibre content. Toasted bread or frozen and defrosted bread has a lower GI than fresh bread. Wholemeal bread is similar to white bread with a high GI because the grains are broken down unlike wholegrain bread where the grains are more intact to be low GI. However, wholemeal bread contains more fibre than white bread. Chocolate and potato crisps have a low GI because it is high in fat which slows the absorption of carbohydrates.
Tip? Low GI foods have a smaller effect on the blood glucose levels and are generally healthier if it is also low in fat and high in fibre. The amount of carbohydrates is very important and too much low GI foods could increase your blood glucose levels, so have low GI foods in moderate amounts throughout the day :)
Source:
https://www.ncbi.nlm.nih.gov/pubmed/17426743 https://www.ncbi.nlm.nih.gov/pubmed/24910231 https://www.ncbi.nlm.nih.gov/pubmed/19160276 https://www.ncbi.nlm.nih.gov/pubmed/20685945 http://www.glycemicindex.com/about.php
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