When using a low-carbohydrate diet, the basic idea of ketosis remains critical to your long-term success. Ketosis involves burning fatty acids as your primary fuel source. Both exercise and diet play a role in your ability to achieve and maintain a ketogenic state. Exercise also plays a role in how quickly you enter ketosis, but this depends on both your training volume and intensity. Consult a health care provider before beginning any diet or exercise program.
Ketosis, the state in which your body primarily burns fatty acids as fuel, takes work to achieve and maintain. Even though you will always burn a certain amount of fatty acids, you must drop your glycogen levels low enough that your body relies mostly on burning fat for energy. Reducing sugar levels is primarily done by restricting dietary carbohydrates. The more restrictive your diet, the quicker you enter the ketogenic state. This state is a delicate balance, so once you achieve ketosis, you must work to maintain it.
Exercise uses various forms of energy for fuel, such as amino acids, fats and carbohydrates. The more you exercise, the more you deplete your body of its reserves, including glycogen. The more glycogen you deplete, the less your body has to use for available energy. When your glycogen levels drop low enough, you enter ketosis. While light exercise will slowly deplete your blood sugar, exercise intensity plays a significant role in not only how quickly you enter ketosis, but how easily you maintain ketosis.
Effects of Exercise
In addition to depleting your blood sugar, exercise also depletes muscle glycogen, but this is also determined by how hard you exercise. A light walk is not a strain for most people, so to significantly deplete muscle glycogen, you would need to walk quite a distance. High speed cycling or heavy resistance training relies heavily upon the glycogen systems in your muscles, so these types of exercise ensure a quicker descent into ketosis.
Benefits of Exercise
Once you achieve ketosis, exercise helps you stay in a ketogenic state. Intense exercise with moderate volume can also allow you to consume a small amount of carbohydrates once you are in ketosis without it significantly affecting your diet. Immediately after performing heavy exercise, your blood sugar is low, and your muscle glycogen is depleted. This is the ideal time to consume a small amount of simple sugars. Your hormones, particularly insulin, will help shuttle the sugar you eat directly into your muscles without disturbing your ketogenic state.