Intermittent fasting is a growing trend in nutrition for its many health benefits that include lowering insulin levels, improving blood sugar and protecting against diabetes and heart disease. Alternatively, because it restricts calorie intake, it might also help you to lose weight.
But since most cyclists have long been prescribed to fuel up with carbs before and after workouts, wouldn’t calorie and carbohydrate restriction hurt your performance on the bike?
INTERMITTENT FASTING 101
The two most popular forms of intermittent fasting are the 5:2 model and the 16-hour fast. The 5:2 model involves eating a normal 2,000-calorie diet five days a week, and on the other two days calories are restricted to around 500. This lowers weekly caloric intake and can help individuals who have a hard time limiting portions throughout the week for every meal, since it only requires you to restrict portions for two days.
The 16-hour fast is a daily fast that involves eating all of your calories in an eight-hour window and not eating for the other 16 hours of your day. Normally, this involves eating an early dinner and forgoing breakfast until the fast is complete. When including this type of diet into a workout routine such as cycling, you would wake up without eating and complete a workout in a carbohydrate-deprived state, relying on fat stores for fuel instead.
THE BENEFITS OF FASTED RIDING
Fasted riding is a trick that has long been used by pro cyclists like Bradley Wiggins to lose weight, improve overall efficiency on the bike and teach the body to use fat as fuel instead of carbohydrates. While the current science behind intermittent fasting is somewhat limited, and studies thus far have only been conducted mostly on mice, the theory behind this for endurance training involves improving fat mobilization and increasing mitochondrial production.
The reason this could potentially be beneficial to a cyclist is that the body contains a limited amount of carbohydrate stores to use as fuel. Since the body has a much larger storage of fats than it does glycogen, the more efficient you can become at burning fat as fuel the more your overall endurance will improve.
In addition to fat burning, fasted training is also thought to improve insulin sensitivity, which means less insulin in the body is required to store carbohydrates. A boost in growth hormone may also help increase strength and require shorter time periods for recovery.
THINGS TO CONSIDER
Like any other diet, intermittent fasting may not be for everyone, and caution should be used when using this diet in conjunction with your workouts. For instance, because you’d be riding without carbohydrates, the potential for bonking — particularly on long or intense rides — is higher.
Because of this, if you want to try cycling in a fasted state, begin with easy rides lasting no longer than 60–90 minutes at an intensity of 3–4 out of 10. If you want to incorporate it on other rides eventually, begin consuming carbohydrates after your main interval set or after you’ve been on the bike for 90 minutes.
For an even more conservative approach, you can also try the 5:2 fasting model. Since most amateur or recreational cyclists ride about 4–5 days per week, it’s easy to coordinate your ride days with your normal calorie days and your off days with your fasting days. While you might not get the benefit of using fat for fuel, the caloric restriction can help with your overall health and weight-loss goals.
READ MORE > SHOULD RUNNERS BE INTERMITTENT FASTING?
Benefits are dependent on not overindulging when you return from your ride and eating a well-balanced diet during your eating windows. Consuming lean protein like fish and chicken in the meals leading up to your fast is important, as is eating plenty of leafy green vegetables. Eating these foods immediately after your fasted rides can also help you recover more quickly and keep from ruining all the hard work you’ve done in the day leading up to your ride instead of loading up on breads and sugars that are low in nutritional value.
When racing or completing long weekend rides lasting more than three hours, consuming some carbohydrates before, during and after your ride in a non-fasted state is still recommended for optimal performance.