On Fasting for Athletes
What I’ve learned.
There has been a lot of noise in the social sphere around fasting as a practice for a couple years now. At first, I mostly dismissed it as another diet fad. Especially as it was championed by the west coast illuminati. You know, crystals and chakras and the lot. Nouveau riche tech wannabee hippies.
Despite this I kept an eye on it and tried to tease out the facts from the hype.
I’ve been playing around with fasting this fall and I’ll give you the general consensus, as I see it, so you won’t be taken advantage of and can use fasting as another tool in your set.
I think what makes fasting seem very different is the methodology flies in the face of some of the tenants of healthy eating methodologies from earlier consensuses. The party line, so to speak, has been to eat healthy, lots of fruits and veg, avoid process foods and eat a lot of small meals during the day. With fasting, all of that is still true except the lots of small meals part.
We have to be careful because there are two important outcomes that people are looking for from all this. First, and this is why it piques the social interest, is the weight loss aspect. We’ll look at this. The second is the impact fasting has on your overall health. Things like disease resistance and basic health markers. We’ll look at that too.
But, as endurance athletes, we have a third outcome we are concerned with. How does this fasting interact with our training and racing? We’ll talk about that too.
What is fasting? Basically, fasting is going without any food for extended stretches. But, here again we have to be careful of our definitions. There are different versions of fasting.
The first is a long fast. This is where you restrict your food for 24+ hours. Typically, people will do this as a sort of cleanse 1 – 4 times a year.
Second is “Intermittent Fasting” which is getting a lot of play these days. This is restricting food for shorter periods of time, 24 hours or less. A version of intermittent fasting that is popular today is a circadian fasting cycle where you only eat in a set window during the day, let’s say 8:00 AM to 8:00 PM.
For people who want to lose weight or lose fat, fasting can help. Your body wants to burn all the available free sugars first before it turns to the deeper fat stores. Most of us endurance athletes already know this. Fasting allows normal, non-athletes, to get to that fat burning cycle without having to run a 100 mile race.
What are the perceived or verified benefits? All these forms of fasting have been shown to help people lose weight and to positively impact their bio-markers. Although the clinical research on humans is light there is extensive data from rat studies and anecdotal reporting that supports positive results.
Here’s the caveat. And you knew this was coming. You only get these results if you incorporate fasting into a healthy diet. You can’t fast one day and gorge on candy and potato chips the next. That doesn’t’ give you any benefit. But, like everything else, fasting, as part of a routine of healthy diet and exercise does seem to have some positive effects.
The most positive thing is that it is a diet tool that works for some people. And if it works for some people then great!
Going deeper, the longer fasting periods seem to cause some interesting adaptation at the cellular level. Again, I’m going to turn to the endurance athlete metaphor to explain it. Whenever we train for an event we go through cycles of stress and recovery. Our body is stressed by that long run or hard workout and then recovers stronger and more resilient for the next cycle.
For these longer fasting periods a similar thing happens. You are putting your body into a nutritional stress state. This causes the cells to dig deeper and burin fat. It seems to lead to an adaptation that, essentially, makes your cells tougher and healthier. Thus, the better bio-markers and the higher resistance to disease.
What’s my experience? One thing I totally agree with is the intermittent circadian fasting. My biggest challenge has always been eating at night and circadian fasting directly addresses this. But I also tried this in the morning as well. The name of the game is to shorten your eating window.
It doesn’t have to be draconian. 12 hours is good starting point. Don’t eat before 8:00AM or after 8:00PM. In the morning I found that it helps to delay that first meal until after 8:00 AM because it keeps you from getting hungry in the morning. All you need to do is drink black coffee instead.
If you are going to do longer fasts you still need to take in fluids and some nutrients. Black coffee and teas are popular along with some bullion or salt supplement. Low calorie stuff with minerals and vitamins.
I did try a longer fast. I went 24 hours. I went from dinner to dinner. What I found was that the first couple hours you think about food and you have some hunger. But, after a few hours it doesn’t bother you. I didn’t feel any deleterious effects. It felt very similar to the end of a multi-hour training session when I’m deep into fat stores.
And that is the transition to the final part of our discussion, “How does this interact with our training and racing?”
Good news! As endurance athletes we practice intermittent fasting all the time. If you’ve done any longer fat-adaptation training, you are essentially fasting. This will also make it easier for you to try fasting because your body already knows how to efficiently burn fat for fuel.
I would be careful of doing hard or long workouts when you’re deep into a fast period. I have no science around this, and I may be proved wrong, but it seems like your body needs some nutrition to rebuild after hard efforts. I’d stay away from speed work or racing while fasting.
But you can certainly push the line to become more fat-adapted and burn more fat. For example, if you’re doing a circadian fast and not eating anything at night, you can get up and run before you eat in the morning. You will feel heavy and lack energy, until your body figures it out, but you’ll burn a lot of fat.
It can be part of your fat-adaptation process. You can experiment with going for low-effort, aerobic efforts in conjunction with your restricted calorie periods to see how it feels and how your body responds.
It is another tool, that when used correctly, in conjunction with a healthy diet and an active lifestyle can have positive impacts on your health. As always, you are unique, you are an experiment of one. Test it out and tell me how it goes.