Sometimes your jog is a slog and your workout a grind. Why? The culprit might be food sitting too heavily on your stomach. Should you eat at all before exercise, and if so, what, how much and how long ahead of time? Ingo Froböse, head of the Institute of Exercise Therapy and Exercise-Oriented Prevention and Rehabilitation at the Cologne-based German Sport University (DSHS), answers some questions on this evergreen topic. Is sport or exercise on a full stomach unhealthy? Froböse: Food intake naturally entails multiple biochemical processes in your body. Digestion begins immediately and very oft…