You have probably heard about Intermittent Fasting from your Keto-diet-following friends, Instagram ads, or perhaps even a medical practitioner. But what is it exactly, and does it make sense for endurance athletes?
First, what is it?
Intermittent Fasting (IF) isn’t necessarily about eating less, but about eating during specific time periods. For example, not eating breakfast until 10am and completing your dinner by 6pm would allow 16 hours of intermittent fasting overnight (which is what is often recommended).
This is both safe and sustainable enough to continue as a lifestyle habit, as opposed to the latest trendy diet.
What are the benefits?
Just as our bodies need rest and recovery in our training, our organs also need to rest and recover from the all-day meals and snacks and significantly more sitting than our ancestors experienced.
Studies show that this rest and recovery can increase fat oxidation, decrease insulin resistance, and even reduce the occurrence or progression of age-related disorders.
Finally, IF is theorized to increase mitochondria biogenesis (a fancy term for more glucose uptake into muscles, allowing better endurance), which seems like it might help multiply the training efforts.
How does it work with my endurance training?
Ultimately, when we are training, we are working to create adaptations, increasing our endurance and strength. Training in a fasted state will diminish these adaptation efforts – you may feel like you have nothing in the tank or are “bonking,” as your body is tapping into the proteins in your muscles to fuel the activity, as opposed to building up the muscles.
However, there is some preliminary evidence that light “recovery-type” running or strength training can be done fasted without detrimental effects to the adaptations and perhaps even adds the benefit of increased growth hormone levels over time (which equals faster recovery!).
Endurance athletes generally require a significant quantity of calories, which may be challenging to fit in with the reduced hours of intake. Meals may need to become larger or more frequent in order to fuel enough in the smaller “feeding” windows.
How do I do it?
For those just beginning IF, start by simply putting off your first meal by consuming coffee or tea (without sugar or cream). Then begin enjoying your dinner meal at an earlier hour.
As you get started, aim for a 10 hour fast (about the time it would be to get ready for bed, sleep, and get ready in the morning!), then gradually make your breakfast later and your dinner earlier to reach 14-16 hours between meals.
Won’t I be hungry?
You are welcome to drink all of the water, tea, and coffee you like in your fasting hours, but you may notice that you don’t need to use them to help fill you up.
Most people find that after just a few days of IF, their hunger is balanced and their energy is increased. Again, the goal isn’t to reduce the number of calories you are eating, just the time in which you are eating them.
So should I start fasting?
While there are no current studies showing that IF can benefit your training and performance, there may be other benefits to your life, especially if you have a family history of diseases such as diabetes, Alzheimer’s, or Parkinson’s.
However, IF isn’t for everyone: if you have thyroid or other hormonal imbalances, or blood sugar imbalances (such as diabetes or hypoglycemia), this should be started with caution and under the guidance of a physician (if at all).
If you want to give IF a try, commit to a minimum of 4 weeks (it takes that long to see the near-term effects). If you don’t like it, you can always go back to your former dining schedule!
Should you find you would like some guidance in navigating intermittent fasting or other dietary theories along with your training program, please send me a note at firstname.lastname@example.org, I am happy to help!