I guess it depends on how much the diet is needed. I know for a diabetic friend of mine, he can't eat potatoes etc as they are too high GI for him. Sweet potatoes are okay.

Generally, avoiding sugar, fructose, bad carb food. Pasta should be wholemeal.... raw foods are better, foods such as sweet potato, quinoa, etc are fantastic as well as seeds and nuts.

Some fruits and vegetables are high GI. Pumpkin, watermelon etc etc...

If its to be a strict diet, it would be worth looking it up and trying to find a list to adhere too.