Tufts University researchers found the glycemic index can vary by an average of 20% within an individual and 25% between individuals. This suggests the often promoted glycemic index probably has limited usefulness in predicting how a food affects blood sugar levels. Lead study author Nirupa Matthan says, "Glycemic index values appear to be an unreliable indicator even under highly standardized conditions."
PositiveTip: The best approach to diet is to choose primarily vegetables, fruits, whole grains, low-fat dairy (or equivalents) and legumes–consumed in an amount to maintain healthy weight.