One of the common objectives of the Base period is to improve aerobic endurance. There are many physiological benefits your body realizes as your aerobic endurance improves, such as an increase in muscle capillaries, greater heart pumping capacity and more plentiful muscle enzymes for converting fat to energy. Related to this last benefit is your body’s greater preference for using fat for fuel while sparing glycogen as aerobic endurance improves. This is an important change because it means a greater reliance on a fuel source each of us has plenty of – fat. Regardless of how skinny you are you have enough body fat stored to fuel many days of continuous exercise. The problem is accessing it.
If you were to stop training for a few weeks your body would begin to lose its taste for fat. It would, instead, gradually shift toward a preference for using carbohydrate, a sugar compound stored in the body as glycogen and glucose, to fuel exercise. So that after this time off, as you started exercising again, most of the energy used in your workouts would come from glycogen and glucose. And your body would not be very good at accessing its fat for fuel. That’s a problem. It means that you will need to continually feed your body sugar from sports drinks, bars, gels and other sources during workouts since you don’t have much stored away. There’s a limit as to how much sugar your gut can process during exercise. So you face the double-headed problem of not being able to take in enough sugar to fuel your engine while beginning to slow your pace despite what feels like a high effort. This is an early stage of “bonking.”
In the Base period, assuming it comes on the heels of having had a break from high volume training, it will take your body many weeks of long, aerobic endurance workouts to train it to once again preferentially use fat for fuel. It will have slowly shifted to a preference for sugar. And the more sugar you feed it, the more it will want. In a winter Base period, the holiday season, with all of its pastries and sweets, may have compounded this shift. You want – actually, you need – to speed up the fueling changes your body goes through as you begin to increase the duration of your workouts. What you eat now plays a role in this change.
The body uses for fuel whatever it is given the most of. If you eat a diet high in carbohydrate, which at some times in the year is necessary (more on that at another time), it will prefer to use sugar for fuel. If you feed it more fat while reducing carbohydrate it will learn to use fat for fuel. That’s a good thing since it augments your aerobic endurance training.
I know what you must be thinking now: Eating fat is bad for your health. That’s an idea which grew out of the 1950s and refuses to go away. Like many “old wives’ tales” there is an element of truth to it. Some types of fat are definitely bad for your health and should be avoided. The worst is hydrogenated fat, often referred to as “trans fat.” This is a fat that nutrition science gave us as a gift 60-some years ago to avoid what they saw as a problem – too much saturated fat in our diets in the form of butter and as an ingredient in many processed foods. As is often the case, the scientific solution was eventually discovered to be worse than the original problem. Trans fat proved to be a better way to cause heart disease than saturated fat. Avoid trans fat. The label of foods that contain it will list it in the ingredients as a “partially hydrogenated” oil. Keep these foods out of your body. You’ll find them in some breads and most snack foods. Read the labels before purchasing.
The “good” fats are found in such foods as walnuts, macadamia nuts, avocado, fish, shellfish, flaxseed oil, olive oil, canola oil and the meats of range-fed animals and wild game. In the Base period slightly increase your consumption of these foods while slightly decreasing your intake of sugar and starchy foods. In this latter category are foods such as bread, bagels, cereal, corn, rice and potatoes. These are best eaten immediately following long workouts to speed recovery. Don’t make the mistake I often come across with some athletes who become so focused on avoiding starch and sugar that they shy away from them following exhaustive workouts. That’s a big mistake. We want to slightly shift your diet toward fat and away from carbohydrate during the Base period. Do not entirely avoid these foods.
By the way, it’s alright to “cheat” on your diet. In fact, you should. Having a small dessert after a meal will not have negative consequences for performance and may do wonders for your peace of mind. My favorite is gourmet, double-chocolate cookies. On days that I workout I’ll have one or two of them for dessert after dinner. Having an occasional baked potato or infrequent pasta side dish is also OK. What we’re trying to avoid in the Base period is a diet dependent on moderate- to high-glycemic carbohydrate foods while emphasizing fat. This dietary shift will contribute to your aerobic endurance fitness.
Complementary Functional Health and Nutrition Consultation