Intermittent Fasting has been around for a while but has been recently gaining in popularity. So, what is Intermittent Fasting (or ‘IF’)? And what do you need to know before ditching your trusty 7am avo on toast?
We caught up with Sports Nutritionist and athlete Steph Lowe (BSpExSc, GDipHumNutr, NSA) to find out what we need to know when it comes to Intermittent Fasting.
One of the key strategies that can be used in conjunction with a real food template, is an extended overnight fast. This creates a shorter eating window, known as a form of intermittent fasting (IF). IF is an excellent strategy for digestive ease and the development of metabolic flexibility and fat adaptation. But there are also many additional day-to-day and long term benefits.
The key benefits of Intermittent Fasting are:
- Digestive ease. As digestion is a significantly high energy requiring process, eating less frequently can support digestive health.
- Fat loss. Without the presence of circulating glucose, we increase fatty acid oxidation and can burn body fat, rather than store it.
- Development of metabolic flexibility and fat adaptation. IF is a powerful tool to becoming a fat adapted athlete.
- Improved sleep. Melatonin receptors turn off pancreas activity, so it is beneficial to eat 2-3 hours before bed time (before melatonin is at its highest).
- Increased endurance. Early research shows an increase in endurance with an 9 hour eating window and therefore 15 hour fast.
- A potential increased muscle mass development. The science is still in animal models, but restricting feeding times to 12 hours can lead to increased muscle mass regardless of food quality.
- Breast cancer protection. A 13 hour fast in women has been shown to be protective to breast cancer.
- Chronic disease risk reduction. Including inflammation cardiovascular disease prevention.
What is the ideal eating window?
IF comes in many shapes in sizes. Some common protocols are known as the full day fast (FDF), the alternative day fast (ADF), and the more recent 5:2 diet – which involves calorie restriction for two days a week and normal eating for five days. None of these are my preferred choice for reason we will discuss. My favourite protocols are as follows, conducted two days per week (to begin).
12:12 (12 hours fasting, 12 hours eating)
A 12:12 is a great place to start as one of the simplest strategies to optimizing your metabolism (whether to become a fat adapted athlete, to assist fat loss or to improve cognitive function) is to delay breakfast. If you have been habitually eating dinner late of an evening and/or eating breakfast as soon as you rise, start planning your eating times to allow for 12 hours between dinner and breakfast the next day. Remember, the definition of breakfast is “breaking the fast”. So while it is still the most important meal of the day, it definitely doesn’t need to be consumed at 7am on the dot. From a practical standpoint, if you regularly eat dinner at 8pm, you will need to make portable breakfast choices to eat at your desk at 8am. But with some forward thinking and simple preparation, this is more than possible.
13:11 (13 hours fasting, 11 hours eating)
A 13:11 is a great IF window and quite easily implemented as a circadian rhythm fast. Eating in line with your circadian rhythm has many benefits, and short term, notably, improved sleep. As we have discussed, it is ideal to eat at least 2-3 hours before bed, before melatonin levels peak. An example of a circadian fast will depend on what time you go to bed, but two examples are:
- Bed time of 9pm: dinner at 6-7pm and breakfast at 7-8am.
- Bed time of 10.30pm: dinner at 7.30-8.30pm and breakfast at 8.30-9.30am.
16:8 (16 hours fasting, 8 hours eating)
A 16:8 is by far the most protective from a disease risk point of view. Research shows not only breast cancer protection in women, but decreased risk factors for cardiovascular disease in both men and women. Logistically it can be more challenging, but prior planning prevents poor performance, as always. A simple example is to eat dinner by 7pm and break your fast at 11am. In women of child-bearing age we recommended the inclusion of fats in this fasting ratio, such as a MCT Coffee. This will then not be considered a therapeutic fast but still extremely beneficial for many of the day-to-day benefits we have discussed.
Your fasting muscle
Please note that it is important that you should first train your “fasting muscle”. We do not recommend attempting a 16:8 until you have competently completed both 13:11 and 12:12. After you do break your fast, factors such as your ongoing satiety and exercise recovery will dictate whether you have been successful. If you fast for too long for example, you may find that you are needing to graze following your first meal, or you may feel more fatigued in the day or days post-workout. Simply track these parameters as a way to determine when you can safely extend your overnight fast.
From an exercise standpoint, please ensure you eat within the hour after a high intensity session. This will mean you will need to be able to finish your session at or before 15 hours into your fast. Aerobic training, which is (or should be) predominantly fuelled on fat is safer to complete earlier in your fasting window as muscle glycogen replenishment is not a primary goal at this point in time.
When shouldn’t you fast?
Fasting is clearly extremely beneficial for our health, but it isn’t for everyone. Quite simply, it should not be attempted under the following circumstances:
- During pregnancy or breast feeding.
- During periods of high stress and/or adrenal dysfunction.
- If you are taking certain medications, including insulin.
- If you have poor blood sugar control. As always, start with real food first and improve your satiety and metabolism before your dive in the deep end with IF.
- After high intensity training, as it is best to fuel within the hour and ensure the inclusion of quality carbohydrates (such as fruit or starchy vegetables) for optimal muscle glycogen replenishment.
Have You Tried Intermittent Fasting?
Steph Lowe (the Natural Nutritionist) is a Nutritionist with over 10 years of experience. Originally trained in Sports Nutrition, Steph is a triathlete herself specialising in metabolic efficiency, long course fuelling, high performance fat loss and elite performance for enhanced recovery and sport longevity.
With a passion for spreading a positive message about real food and the incredible affect it has on performance, Her extensive nutritional experience spans from elite athletes, to schools, and corporations, where she has educated people about the importance of real food for productivity and performance.
Steph Lowe’s new book Low Carb Healthy Fat Nutrition, is a “real-food-only” lifestyle that Steph has been personally living and transforming the lives of clients for more than 10 years. Steph’s new book gives readers the tools to transform their daily habits and make sustainable, long lasting change to their bodies and mindset. LCHF Nutrition includes 150 delicious, easy and no nonsense recipes that can be thrown together in around 10 minutes – no experience needed, no excuses necessary.