Despite its celebrity status, the GI diet has something going for it that sets it apart from most other popular eating plans - doctors, nutritionists and dieticians actually like it! The GI diet is based on the Glycaemic Index, a scale which ranks foods based on the effects they have on blood sugar.

The Glycaemic Index runs from 0 to 100, with foods that have a small effect on blood sugar given a low value, while those that cause a large rise in blood sugar having a high value. Following the plan requires you to eat plenty foods with a low value and avoid those with a high value.