There has been a lot written recently about the merits of fat, the evils of carbohydrates, and the obvious scientific idiocy of those that propose such a diet for performance-oriented athletes. Athletes and sports scientists sure take their nutrition personally! However, as is often the case, the truth hiding beneath the rhetoric is never so cut-and-dry. Yes, fats can be very good for your health and your performance. But the wrong fats can be terrible things to put in your body. (Think about the difference between an avocado and a deep-fried twinkie!) The same can be true for carbohydrates and proteins. Most foods with which a reasonable athlete would choose to fuel their workouts are neither inherently good nor bad. We can argue all day about what athletes should eat, but unless we include a discussion about when they should eat it, the point is being missed.
When you are planning your workouts for the week, do you plan to do intervals every day? Why not? We know they are good for your performance. Why not just do more intervals? Speed work all the time! Of course you wouldn’t do that, because each workout has a purpose and performance is multifaceted. Whether or not you are familiar with the concept, you employ “periodization” when planning your training. Periodization dictates that there is a time and purpose for each training session. Furthermore, there is a season for different types of training. Your weeks of “base” training will look different than your “build” phase as you lead into race season. And your “taper” will look different still.
The concept of periodizing training load has been around for decades, and it is a widely accepted foundation of sports science. The same ideas can, and should, be applied to nutrition as well. The fuel your body needs to support a week of “base” training (slower, longer runs at low intensity) will look very different than those which are required for ideal dietary support of higher-intensity weeks (track work, hill repeats, etc). These are very different physiologic efforts.
When running at an easier pace, your body is more apt to burn fat for its primary fuel. This is a very efficient process that allows you to utilize stores which, in even the leanest athlete, are plentiful (tens of thousands of calories!). As your effort increases, you switch to a metabolism which is more dependent on burning carbohydrate for fuel. Carbs, stored as glycogen, are a very limited resource (only a couple thousand calories, at best). If you can train your body to work at higher intensities while still preferring to burn fat, you will achieve a higher level of “metabolic efficiency.” You will avoid the swings in blood sugar levels and the resultant, regular need to squeeze down another gel. How does one achieve this efficiency? The answer is “practice and periodization of diet.”
If you want your body to increasingly prefer burning fat as its primary fuel, you have to train it to do so. Rather than a typical endurance-athlete diet consisting of 60% to 80% carbohydrates, you must decrease your carb intake and give the body more fat to use as fuel. If the constant onslaught of carbohydrate is mitigated, along with the resultant insulin response, then the body will begin to lose its dependance on regular carb intake. But it’s not as simple as that. That is the part that, when presented in isolation, gets people riled up! How can an athlete maintain a high level of intensity on such a diet?!? Well, remember my prior mention of “periodization”?
The advice and expertise that is often absent in dietary articles online or in print, is that an athletes’s nutrition must support the task at hand. Train your body to use fat more efficiently, yes. But as you accomplish that, you can begin to use high-glycemic carbohydrate sources as “jet fuel” for your intense training and racing efforts. Carbohydrates, and even sugars, are not bad! Use them for a dedicated purpose, and they will provide huge benefit to your performance.
Proper dietary periodization should work in this manner:
Of course, your fueling protocol will be specific to your needs. This will vary based on your physiology and your goals. If you primarily run 5Ks and 10Ks, then your needs will be very different than that of an ultra-marathoner or multisport athlete.
Every workout has a purpose. In the same way, every meal should have a purpose. Sure, some runs are just for fun. Some meals are just for fun as well! That’s a good purpose in my book. But to the degree that your training is goal-oriented, your diet should be as well. Don’t let this crucial, often-neglected component of your training be the undoing of your hours spent running. You can’t outrun a bad diet! Don’t run so you can eat more. Eat so you can run better!