Becoming a GI Joe
All carbohydrates have a value on what is known as the `glycaemic index’ (GI), which indicates how quickly that carbohydrate is metabolized by the body and converted into glucose. The lower a food’s GI, the longer it takes to be converted. Foods with the highest GIs are the ones that will have the most profound and immediate effect on your blood-sugar levels. All the carbohydrates on a weight- loss and insulin-balancing regime should come from the lower ranges.
There are two indexes: the glucose standard, which rates glucose as having a GI of 100 and the white bread standard, which is based on white bread being equal to 100. Other carbohydrates are assigned comparative ratios based on these figures. It doesn’t really matter which index you adhere to, for they both give a pretty good – and sometimes surprising – insight into the speed with which certain carbohydrates are assimilated into the bloodstream.
Below are a few GI values of common foods, based on the glucose standard. Of course you are not expected to remember each specific food’s value, so to make things easier, opposite are two simple tables showing you how to classify fruit and vegetables into those with a low GI value (under 20), those with a medium value (20-60) and those with a high value (over 60).
Each carbohydrate can also be evaluated by its density value. This is the amount of usable carbohydrate in relation to fibre and water content – the more fibre and water a vegetable or fruit contains, the less usable carbohydrates it will have. The most dense carbohydrate foods are pulses, wholegrains and starchy vegetables, particularly when they are cooked and their fibre is broken down, these will raise your insulin levels, so always be aware of this. The table opposite contains a list of low-density carbohydrates that should form the basis of your carb intake on a low-carb diet.
Not only do many fruits feature highly on the GI scale, but a few should also carry a carbohydrate density warning sign. Bananas, dried fruit and concentrated fruit juices are all a bad idea if you are trying to balance your blood sugar levels. It is best to avoid these totally until your blood sugar and weight have normalized, and then carefully re-introduce them into your diet.
Focus on fibrous vegetables that can be eaten raw or steamed – the type that lose a lot of water whilst cooking. This will mean increasing your intake of leafy green vegetables, such as Swiss chard, green cabbage, kale, bok choy, rocket, spinach and endive.