Fasting before running is a contested topic. From elites to first time marathoners, many people have considered implementing fasted runs into their training regimens. We’re told often that runners need to fuel properly, but is there a time and place where fueling properly means eating nothing at all?
Fasted runs are done to train the body to burn fat over carbohydrate stores while running. Canadian physiologist Trent Stellingwerff has done work on this topic and used three elite marathon runners for a case study in 2012. Over a 16 week period the marathoners did 20 percent of their weekly mileage in a fasted state. As the runners got closer to race season they decreased the frequency of their fasted runs to allow for higher intensity training which they had to eat before. Two of three athletes had personal bests in the marathon after working fasted runs into their training. For the third runner it was their marathon debut so there was no basis for comparison.
Morning is the most practical time to do a carb fasted workout. Because you’ve already fasted overnight, you can hop out of bed and start your workout. Be sure to eat a full meal that is carbohydrate heavy after exercise. For example, carrot cake slow cooker steel cut oats or homemade pancakes would do the trick. Eat normally for the rest of the day.
So are you faster after fasting? Potentially, but not necessarily. As with most things running related it’s very personal. Running fasted is certainly something to consider but not a must when training for an endurance sport. Some runners have seen benefits and implemented fasting into their routine, where others find it provides little benefit and leaves them feeling sluggish and weak. Especially for people new to endurance athletics, it’s recommended to begin fueled for your workouts before introducing fasted or depleted exercise.