The GI diet or Glycemic Index was developed by Dr David Jenkins, professor of nutrition at the University of Toronto.
The essential idea behind the GI diet is to measure how fast your body breaks down food to form energy.
The advantages of this being that you can figure out what foods take longer to be broken down and therefore take a longer time before you feel hungry again. With the GI diet, the point is that you won't end up suffering from knawing hunger and feelings of starvation.
By focussing on foods that are relatively low in calories but which the body uses slowly, you can go for longer without suffering. Thus making losing weight considerably less painful
It also uses a simple colour coding system to help guide you as to which foods to eat. Green is for go and these represent foods where you can happily consume as much as you like.
Orange is for slow down so these foods are okay to be eaten on a moderate basis. Red is for stop and these foods are non-starters if you're hoping to shed those pounds. So there's no complicated calorie counting and weighing up of options, it couldn't be more straightforward.
It's also far less likely to damage your health as there's no drastic deprivation involved or cutting out of essential food groups. Instead a scientific understanding of how the body breaks down food to produce glucose for energy is used to give you practical advice on how to lose weight with the minimum of discomfort. It's realistic, simple to follow, and not for masochists.