Intermittent Fasting and Endurance Training (part 3: “sleep low”)


We discussed the health intermittent fasting (IF) HERE, and how to safely/strategically incorporate IF into “simple” (1x/day, aerobic) endurance training HERE.  Now, let’s look at how we can incorporate the IF/low-carb strategy into a training program in which we train 2 or 3 times per day…

I posted a detailed video on the ECo Insiders group page where I discuss how I have found success with the “sleep low” strategy I discuss below. To join in on the conversation, ask questions, and see the video, join the ECo Insiders today!!

We know that carbohydrates are key to optimal performance. Simply put, we need carbohydrate to go hard; carbs are the primary fuel for anaerobic, high-intensity exercise AND carbs allow us to keep going during long endurance events.

So, with that said, it my seem paradoxical when I say that exercising with high carbohydrate availability may have some negative effects on endurance training and performance.

The positives of CHO-availability are obvious: high CHO intake helps retain glycogen levels, allow us to perform better during high-intensity sessions, and maximizes strength training.

But the negatives??

Chronically training with high CHO-availability may actually suppress endurance-exercise-induced adaptations like lipolysis (using fat for fuel) and mitochondrial biogenesis (making more and larger mitochondria… the “powerhouses” of cells!).

So, it’s important to understand the value of PERIODIZING your macronutrient intake (CHO, PRO, and FAT).

Nutrient periodization of takes on two roles: micro-periodization (day-to-day) and macro-periodization (months).

I’m going to focus on the micro-periodization; strategies you can implement on a day-to-day, week-by-week, basis. This may also be referred to as “nutrient timing.” In other words, I’m going to focus on how you can time your CHO intake to optimize your endurance training.

I discussed the values of training “low” in PART 2.  Let’s look at how you can strategically incorporate CHO into your daily diet to optimize your training.

Keep in mind, the goal is to optimize training. We want to get the most physiological benefit out of the time we put in. We are thinking LONG TERM (i.e. “I want to be super-fit in June.”) by making strategic SHORT TERM decisions (i.e. “I will subject myself to ‘uncomfortable’ training because I now I’m making long-term gains.”).

I’ll focus on one particular strategy that has shown been shown to work (peer-reviewed, scientific data) and I have implemented with success (personal, anecdotal data). It’s called the “Sleep Low” strategy.

Simply put, the “Sleep Low” strategy times your CHO intake so that you are training in a CHO-depleted state for you low-intensity, aerobic sessions and in a CHO-loaded state for your high-intensity sessions.

In the first study to investigate the “Sleep Low” strategy, the researchers split up a group of triathletes into two categories, both of which ingested ~6 g/kg/day of CHO). The athletes performed both low intensity (below their aerobic cap) (LIT) and high intensity (HIT) sessions. The “control” group ate the CHO through the day. However, the “Sleep Low” group was deprived of CHO from the period immediately after their HIT session until after the end of their subsequent LIT session. After the HIT session, the “Sleep Low” group ate a low-CHO meal and performed the LIT session in the morning after an overnight fast. Once the LIT session was done, the “Sleep Low” group refueled with high-CHO until their next HIT session. This protocol was repeated over and over.

Below is an simple example of how the week looked for the “Sleep Low” athletes:

The results of this study indicated that there were benefits the “Sleep Low” group showed compared to the control group.

1.    10k performance improved in the “Sleep Low” group.


2.   Rate of Perceived Exertion (“how hard the effort felt) decreased in the “Sleep Low” group both during a sub-maximal test and at the end of a race!


3.   CHO oxidation decreased  AND efficiency increased at 70% of maximal aerobic power. Taken together, the “Sleep Low” athletes used les CHO at the same workload. 

At the end of the article, the authors concluded that, “periodizing [CHO intake] within a training program to include both sessions with high-fuel support to promote high-quality/HIT and sessions/recovery promoting enhanced metabolic adaptation can lead to a superior training outcome.”

So, the science points towards this being a good strategy. But, like most things, they only are effective if they work in real-life. So, I tried this strategy. Here are guidelines for how I did it (and continue to do it):

  • All a.m. sessions are performed in a fasted state. Typically I do the a.m. session around 7:00 a.m. with a ~12 hour fast.
  • If I have a second session in the afternoon that is AEROBIC (LIT), I eat a low-CHO recovery meal and eat low-CHO the rest of the day
  • If I have a second session in the afternoon that is ANAEROBIC (HIT) or STRENGTH, I eat a high-CHO recovery meal and stay “carb’d up” until the p.m. session.
  • After the p.m. session, I’ll eat a meal lower-CHO and low Glycemic Index meal (the CHO I eat are complex and low in sugar).

I do this because I understand the physiological benefits. It doesn’t always feel good, but I have no trouble completing aerobic workouts when carb-depleted. I also understand that I want to maximize the HIT sessions, which is really where I need to excel to make certain gains in performance, so adding CHO to my diet is a welcome “gift.”

NOTE:  I’m not trying to lose weight or modify body composition during this. So, this strategy is NOT a calorie-restriction diet. Rather, it is a method of manipulating macronutrients and training stress to optimize training.

NOTE:The other thing to note is that this article is simply meant to provide some insight into the “Sleep Low” strategy and give a little bit of information on how I’ve incorporated it. I present A LOT more details on our ECo System Group page where I allow Q&A, give examples, and give advice for athletes who are interested in trying this.