Most recently studies have shown that the average American breakfast contains more than 22 teaspoons of sugar. To put it into perspective, that is more than double the amount of sugar a person should have in an entire day.
Don't think you have a sweet tooth? Try taking a look at the ingredients on your next sports drink or protein bar. You'll likely find sugar such as: cane sugar, maltodextrin, fructose, dextrose, and corn syrup, hiding in your drinks and meals.
Now, there is a time and place for everything and runners preparing for a marathon do need to make sure they have fuel to run on such as GU packets that do contain some sugar. However, being a runner shouldn't be a free ticket to eat over the daily sugar limit.
Contrary to popular belief in the running world, recent research has shown that a runner consuming high-glycemic (Gl) foods (like white bread, ice cream, or high-sugar energy bars) an hour before actually causes the runner to become fatigued more quickly. The study from the Journal of Science and Medicine in Sports found that athletes performed significantly faster after eating a low-Gl meal rather than a high-GI meal.
To sum it up, when it comes to sugar, whether it is natural sugar (like molasses or honey), or processed sugar (like cane sugar or high fructose corn syrup) too much is harmful for your health and training. What's hard to accept is that it is easy, in an American diet, to get too much without even knowing it.
Runner's World encourages runners to try to replace their sugary energy bar with a more natural selection like an apple and peanut butter (no sugar added of course).
Prepare your meal menu daily, educate yourself about the sugars hiding in your foods and remember that running doesn’t give anyone a ticket to eat unhealthy foods.