***DISCLAIMER: I am not a doctor or nutritional specialist in any way. Restricting calories and fasting may not be for everyone, and could be dangerous if not done properly especially in the face of contraindicated medical conditions. Please be smart and consult an appropriate expert. You’ve been warned…***
Looking at the research is where the idea of intermittent fasting gets interesting. Some vague research inklings (regarding longevity) are what got me to try it and the fact that I just felt better is what kept me doing it, but the numerous potential areas that it effects in a positive way is what has caused me to redouble my interest in it.
Tissue healing and Regeneration | Fasting for Endurance Athletes
Fasting seems to trigger our body to begin a significant repair process called autophagy, which is a process where the body maintains a balance by culling damaged proteins, organelles and entire cells and replacing them with new ones. Interesting that the consistent ingestion of calories and the cells having to process this (needing to process the nutrients that are being forced on them?) prevents this from happening under normal feeding circumstances.
Short-term fasting induces profound neuronal autophagy Changes in the brain
Fasting activates macroautophagy in neurons of Alzheimer’s disease mouse model but is insufficient to degrade amyloid-beta. More brain changes, with a focus on Alzheimer’s
Influence of age-related learning and memory capacity of mice: different effects of a high and low caloric diet. Effecting learning and memory capacity
Mitochondrial degradation by autophagy (mitophagy) in GFP-LC3 transgenic hepatocytes during nutrient deprivation. Effects to the liver.
Intermittent fasting improves functional recovery after rat thoracic contusion spinal cord injury. Interesting because the group that was fed daily but with the same calorie restriction as the groups fasted every other day (25% caloric restriction) didn’t heal as well as the fasted groups.
Metabolic Changes | Fasting for Endurance Athletes
It can decrease insulin in the body, increase insulin sensitivity and lower blood sugar levels. ‘Nuf said.
Glucose tolerance and skeletal muscle gene expression in response to alternate day fasting.
Hormonal Changes | Fasting for Endurance Athletes
The release of Growth Hormone can increase up to five times! Growth Hormone (GH) also accelerates tissue repair, increase muscle growth and fat burning.
Inflammation | Fasting for Endurance Athletes
Interleukin-6, C-reactive protein and biochemical parameters during prolonged intermittent fasting.
I found dozens and dozens of other articles on the subject — notables include one that shows fasted mice had increased resistance to Salmonella infection; and numerous articles on patients nearly eliminating side-effects when undergoing chemotherapy, cancer prevention, and longevity — but for now let’s just take the above effects on tissue repair, metabolic changes, hormonal changes and inflammation.
Are these effects applicable to endurance athletes? Clearly I think the answer is “absolutely.” Improved insulin and glucose sensitivity, increased growth hormone release, improved tissue repair processes, and better management of inflammation sounds like an all-star list of effects for any endurance athlete.
The real trick is implementation, I think. It’s not as if a long distance triathlete or marathoner is going to be able to start fasting every other day and not expect their training to suffer on some level. Still, the upside is tantalizing enough to warrant some experimentation.
I have done some experimentation already so let me share what I have come up with so far:
Times to fast
Recovery periods : This can apply equally to short periods of recovery (1-2 days) as well as long (1-week, 2-weeks, or more). What better time to get a little assist in tissue repair, growth hormone release and inflammation management? These don’t have to be very long in duration…in yesterday’s article I outline that I only fast for between 16-24 hours once a week. This is pretty easy to do during a 2-day recovery period in your training plan or to do a couple times over a 10 day step-down period.
Moderate effort days/weeks : Any time the volume and/or intensity is not setting any records given your fitness level. Even if I have 4 or 5 days of training ahead of me but the distances and intensities are not exceptional given my training up to that point, I can usually sneak in one day of fasting without feeling run down. In fact, I’m usually left feeling pretty spry — I can’t say for sure that it’s any or all of the effects discussed above but I get the feeling that at least some of those positive effects are making their mark.
Times to avoid fasting
During very intense training periods — exercising very intensely (intervals) or during periods of high volume (lots of distance). Since the goal of intervals is to reach as high an output as we can manage, removing any barriers to this — and being calorie-restricted will likely down-regulate our ability to produce power — is key. Additionally over multiple days of long workouts it’s important for similar reasons to be fed, however I think there is a bit of gray area with distance. There may be instances where it is in our interest to run the proverbial gas tank empty — you can read more about this in my article about why I think bonking can sometimes be good for you.
It’s important to find what works for you though. If you find yourself struggling to get through workouts that you normally wouldn’t have a problem with then tweaking your fasting schedule is a good idea. Not everyone is going to respond the same way so start where you’re comfortable (and based on what your doctor recommends) and make little tweaks to find your optimal effect.
There are enough benefits on the table that it’s hard to ignore fasting as a supplement to general health and wellness, but if we can extract enhancements to our training regimens then it definitely warrants a closer look.
Have any experience fasting? I’m always interested in finding out what works and doesn’t work for others so let me know in the comments or reach out on social media…
***DISCLAIMER: I am not a doctor or nutritional specialist in any way. Restricting calories and fasting may not be for everyone, and could be dangerous if not done properly especially in the face of contraindicated medical conditions. Please be smart and consult an appropriate expert. You’ve been warned…***
