Eating right, aka dieting, should not be the exception, it should be the rule.  Runners, walkers, or any endurance athlete should not be focused on going on a diet as much as incorporating healthy eating into one’s daily diet.  And it’s really not that challenging or confusing to eat healthy in support of an active lifestyle.  Complex carbohydrates are your friend, sugar is not.  Saturated fat doesn’t equal a good choice while lean protein is good, but not in excess.  When shopping for food stay away from boxes and anything on a label that you cannot pronounce.  Chose real foods that have expiration dates in this century, and finally, if you consume more calories than you burn the excess has to be stored somewhere.