I have been practicing intermittent fasting for 4 months now. It is known that the reported beneficial health effects from caloric restriction… can be mimicked by alternating periods of short term fasting with periods of refeeding, without deliberately altering the total caloric intake. This is intermittent fasting.
Self-Quantifying the Effects of Fasting
It is both informative and motivating to track certain variables while you are practicing caloric restriction or intermittent fasting. Useful measures that are freely available (some involving a trip to the doctor) include the following:
- BMI (body mass index)
- body fat percentage
- blood sugar
- cholesterol levels (e.g. LDL)
- hours slept
- resting heart rate
Measures of physical performance can also be tracked such as weight lifted, reps completed, distance run/walked/cycled/rowed.
Measures of psychological health, resilience and performance can be measured with the Mindware Lab Test Battery or the HRP Lab Test Battery (with i3).
Personal Recommendations for Intermittent Fasting Brain Cross Training
- Experiment with different fasting programs to find out what you can successfully make a part of your lifestyle. These diets should be thought of as a long-term lifestyle change – not a temporary diet plan. It is for this reason that permanent caloric restriction (e.g. 20-25%) diets are not recommended, as they tend to be unsustainable in the long-term. I have opted for an alternate day intermittent fasting diet, but I regularly increase my calorie intake on fasting days to over 600 calories, to supply my energy demands for long distance running. I have also found that my overall energy levels and cognitive health has improved with a reduced carbohydrate intake during my unrestricted diet days. I have also tried a 2:1 diet, with 2 days off and one day on the 600 Calorie diet.
- The diet should, after a couple of weeks, be helping you feel good – physically and mentally. You should feel sharper and more productive. If you are feeling fatigued, over-stressed, or run down, or are experiencing disruptive swings in mood and energy levels, then the diet is not working and should be stopped or adjusted. I believe, however, that some stress-reactivity should be tolerated during the first weeks as your body adapts to the new regime.
- You may need to develop a tolerance for feelings of hunger on fasting days – which in itself is not a negative. Hunger itself stimulates new brain cells via the hormone ghrelin.
- The idea of caloric restriction/fasting is to create an energetic stressor to activate all the benefits of the hormesis response. But if you overdo the fasting, or skimp on essential nutrients, you will cause the kind of system breakdown that you are trying to build resilience to – leading, for instance, to insulin resistance and poorer glucose metabolism. For women, the effects of being overstressed from fasting may be more dramatic.
- Related to the above, combining fasting with intense exercise may result in a stress-reactivity response, with sleeplessness and anxiety. On a couple of occasions I have experienced an intense stress reactivity during the night after long training runs during the day, with insomnia, restlessness and anxiety. I would recommend stocking up with a high carb meal the evening before endurance workouts, and ensuring that on the training day you are also well fueled with carbs.
- Ensure that you don’t become weaker through muscle loss. Maintain at least 0.8 grams of (complete) protein per kilogram of body weight – e.g. 64 g for a 80 kg man (i.e. 256 calories) ; 45 g for a 56 kg woman (180 calories). Ensure that most of your protein intake is plant based if you are consuming more than 10% protein in your overall calorie consumption. I have switched my diet to a primarily vegetarian one for a wealth of health reasons, and find that hemp protein supplementation has been excellent for maintaining strength during intermittent fasting and athletic training.
- Drinking coffee may be beneficial for fat-burning, especially during a fast. One study found that an infusion of epinephrine (a hormone that coffee increases) during 48 hour fasting up-regulated fat-burning and metabolism. Epinephrine also lowers appetite, which can be helpful for people trying to stave off hunger during a fast.
- Avoid alcohol during fasting. The inebriating effects of alcohol are more pronounced during fasting, and alcohol is itself relatively high in calories.
- Meditation on fasting days is recommended. In my own experience, mindfulness meditation before sleep on fasting days helps counteract stress-reactivity, and helps with overall adaptation to prolonged intermittent fasting.
- Phytonutrient consumption on fasting days is recommended. The health and cognitive benefits of phytochemical-rich nootropics such as green tea, blueberries, and Turmeric may be heightened when the adaptive cellular stress response is already ‘primed’ by fasting.
- Intensive computerized brain training may also act synergistically with fasting, with greater neuroplasticity and brain health benefits when the adaptive cellular stress response is already primed.