A new study shows that diets based on the glycemic index, like the South Beach Diet, do not effectively control blood sugar levels.
The glycemic index, which measures how quickly carbohydrates convert to sugar in your blood, has never been accepted by many dieticians.
This study, which examined food questionnaires from more than 1,000 people over the course of five years, did not find any link between the glycemic index of foods and the blood-sugar levels of participants.
Previous, smaller studies have had different results, including one that seemed to show that a low-glycemic diet lowered risk of heart disease. Supporters of the index claim that foods lower on the index make a person feel full longer and reduce cravings, helping with weight loss.