If you want to get the most out of your running, accept that your diet and how you fuel matters.
While you’ll want to pay attention to your nutrition ahead of all runs, workouts and races, keep in mind that the half and full marathon distances especially demand extra attention to detail. Run out of fuel mid-run and you might find yourself coming painfully close to the dreaded wall or perhaps even having to stop or do a slow jog to the finish.
Carbs are still king
Most runners are already aware of the importance of carbohydrates for performance. Carbs are the preferred fuel source used by the body during aerobic endurance exercise and especially higher intensity efforts. Stored as glycogen in the liver and muscles, this is efficiently broken down into glucose and transferred via the blood-steam to the muscles where it’s metabolized for energy.
Most runners already prioritize carbs as part of their diets. Typical recommendations suggest that 50-60 per cent of one’s daily intake should be in the form of carbohydrates. What might that look like on the dinner plate? When you think carbo loading, think of whole grains, legumes, fruits and vegetables. To maximize performance, carb-loading is the process of increasing the proportion of consumed carbs up to 80 per cent in the days leading up to a long run or race.
In general, you probably don’t need to make too many changes to your diet to fuel your usual running and training. Consuming carbs both before and immediately following a longer run or any workout (in combination with some protein) will help hasten recovery and also avoid a sugar crash.
Fats are fuel too
Fats are also an abundant source of potentially usable energy but aren’t easily (or quickly) oxidized by the body. Only after burning through its preferred source (carbs) will the body begin to dip into its fat stores. These stores are however plentiful in every human body so there’s no risk of running out of them.
There are several ways to improve the body’s ability to use fats. The most common one is low-intensity exercise including brisk walking and very slow, easy running. This is the reason why long runs are often done as long and slow workouts. Additionally, the body will begin to increase its oxidation of fats late into a long run, when glycogen (carb) sources begin to diminish. One additional way to optimize your use of fats is to complete depletion runs. This is done by running in a semi-starved state, such as first thing in the morning before breakfast.
While risky, some coaches suggest (occasionally) depleted long runs and workouts as part of training. Doing so will makes runners’ bodies quickly burn through all available glycogen stores and then be forced to use fats while running at a higher intensity. As you might expect, this type of run is both mentally and physically tough and should be approached with caution.