Readers following “The Personalized Diet,” regularly test their blood to check how specific foods affect sugar levels. Dieters who have never tested their blood sugar before, understandably, have questions. One question recently came into The Personalized Diet Facebook page and Dr. Segal answered.

“Does anyone know what a “bad” food spike would be defined as – is it +40mg/dL higher than your fasting blood sugar after 30 minutes?”

Dr. Segal Answered: Foods that raise your blood sugar levels by more than 40 mg/dl above the baseline starting value just before the meal may be considered a bad food spike. However, note that responses vary across people. For example, in diabetics glucose levels may rise over 100 mg/dl following meals and for them a 40 mg/dl may be relatively low in comparison to other meals.