Q: Is it more healthful to exercise before you eat or after?

Dr. Mirkin: Many studies show that exercising after you eat lowers high blood sugar levels far more effectively than exercising before you eat.  A high rise in blood sugar after meals damages cells to increase risk for heart attacks, strokes and nerve damage such as dementia, blindness and deafness, even in people who are not diagnosed as being diabetic.  In this study, 20 minutes of self-paced walking lowered blood sugar levels in diabetics more when done two hours after eating dinner than before eating.  Exercising after fasting barely lowered their high blood sugar levels at all  (Journal of the American Medical Directors Association, July 2009).

Muscle contractions drive sugar into cells without needing much insulin.  These people were out-of-shape diabetics who walked slowly and for only 20 minutes, two hours after meals. Longer and more intense exercise lowers insulin and sugar levels even more and would be even more beneficial in preventing disease and prolonging life.  I recommend exercising both before AND after eating.