According to conservative USDA estimates, on average, Americans consume 22 teaspoons of "added sugars" each day, or 355 additional calories, more than double what is recommended by the American Heart Association.
Research shows that eating sugar-laden foods or drinks with a high glycemic index, like white bread, ice cream or high-sugar energy bars about an hour before a run may cause you to tire more quickly.
Sugary foods consumed during high intensity exercise, however, can help you train harder and longer. If running for more than 60 minutes, 30-60 grams of simple carbs for each hour of acitivity. If exercising for an hour or less, water is all you need.
Immediately post-run you are also allowed to consume sugar, guilt-free. At this time muscles are craving sugar to replenish glycogen stores to prepare for next exercise session.
As for the rest of the day, shelf sugary foods.
Studies suggest that sugar activates the brain's neural pathways in a manner similar to taking narcotic drugs. Just like morphine, the more sugar you eat, the more you need to feel the effect. The more you satisfy your sugar cravings and your sugar calorie intake sneaks upward, the more likely it is that you'll be trying to run off a Buddha-belly.
For the all the details, read the full article, "Sugar Shock" in this month's issue of TrailRunner magazine.