Talk:G.I. Diet

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Poor analytical techniques are used in determining Glycemic Index. The basic assumption that a "50-g carbohydrate portion of a food" , i.e. a portion of food containing 50 g of digestible carbohydrate, can be compared with 50g of glucose is erroneous. As both of these food portions have differing chemical units, the calculation of GI by comparing "areas under curves" does not give a dimensionless GI number. The resultant "GI number" has units "g glucose released from a portion of food containing 50 g of digestible carbohydrate per g glucose". Only food containing pure glucose and/or starch can have a true Glycemic Index. Other carbohydrate foods such as the simple sugars fructose and galactose and the di-saccharides lactose and sucrose need considerable processing by the body before they become glycemic. For example, fructose is partially converted to glucose by the liver. However, the amount converted is dependent on both blood glucose and liver glycogen storage levels. As any excess fructose cannot be stored in the liver, it is converted to fatty acids for subsequent storage as body fat. In this case. not all fructose is converted to blood glucose within the prescribed reference time of say 2 hours.This means that the total grams of digestible fructose overestimates the amount of fructose converted to blood glucose over the reference time. This results in giving false low Glycemic Index values for fructose.