I’m excited to introduce a guest post from an elite athlete in the midst of an incredible ultrarunning career. Believe me, not many athletes can write—or do much of anything except perform and veg out on the couch recovering before the next workout. Zach Bitter, record setting ultramarathon runner, is different, as readers of his popular blog  already know. Zach holds the American record for the 100-mile run of 11 hours, 47 minutes. That’s running all day—400 laps around a regulation track—at seven-minute per mile pace. Go try to run a single mile in seven minutes to gain a full appreciation for his supreme effort.
Zach has achieved some notoriety in the ultra scene as a dedicated fat-fueled athlete. (You can read his story here .) He dabbles in keto during his base building training cycles, believing that it speeds recovery and reduces the stress impact of his workouts. His fueling strategy for competition is more nuanced, and he has a lot of important things to say on the matter. His post offers insightful commentary about periodization of nutrition. Here is a quick sound bite from Zach about his big picture goals with becoming highly fat- and keto-adapted: “I strongly believe that the less you have to fuel during a race, the better.” Enjoy this message from Zach, and we hope to check in with him again in the future.
Nutrition has continued to come closer to the forefront of conversations everywhere in recent years. Certainly, this is in part due to the ease of access to information, and the seeming growth of all kinds of approaches—which all boast success stories in which the reader can place their faith. It is a fascinating crossroads for many people. When we look at things in black and white it can become quite easy to get confused. How can one nutrition approach work so well for one person, but fail for another? I am a big advocate for starting with some simple principles, and ultimately building from what you find in order to fine-tune things specific to you as an individual. People lead drastically different lifestyles. This makes following someone else’s approach difficult without some fine-tuning to your own personal lifestyle.
It is for this reason my first piece of advice for someone starting their journey into health and nutrition is to turn to whole food options. If not already done, removing fake processed food is a big first step. From there, I see a blank canvas to build from in a way that matches what your goals and lifestyle require.
With that all said, I want to zoom in for the purposes of this article. Fast forward along the journey where you have eliminated all the fake processed garbage, and move into fine-tuning things within a high fat or Primal approach to nutrition.
When you dive into the world of high fat, or keto, nutrition you often find no shortage of people advocating for nearly if not entirely eliminating carbohydrates. I don’t see anything inherently wrong with this approach, at least to start, but do think there is some wiggle room here for those of us who follow a periodized training approach that makes your lifestyle look drastically different at various points of the year. For example; my personal training plan for ultra-marathon races has me at times training for upwards to 20 hours a week when in peak training. These peak training weeks also often include speed and strength work. During these phases of training I am a bit more liberal with the amount of Primal approved carbohydrates I eat. On the other hand, there are weeks of the year when my number one goal in regards to training is to simply rest and recover. During these times of year I do not have a need for carbohydrates, and in fact, have found reason to believe they can even be counterproductive. For me, these phases of the year are met with a more clinical definition of a ketogenic diet (30-50 grams of carbohydrate per day).
This “fuel your lifestyle approach” presents a greater need to be a bit more flexible with nutrition than a typical “plug and play” approach you might find that would have you eating basically the same things all the time. I find this exciting and motivating, as I can always look forward to some change or variance in food groups when I am going in and out of different phases of training.
Where to begin? In a perfect world everyone I work with would come to me at the onset of their training plan, or priority goal—whether that be a race, event, or simply to improve their fitness and health. For purposes here I will start from the beginning. If you find yourself part way, you can look where you are, and find a logical jump-in point. The beauty of this approach is you can always revisit it from the beginning when you finish your current goal, hit the reset button, and plan your next adventure or fitness goal.
Jump-Starting Your Fat-Burning Engine
My goal with this program is not necessarily to get you to be as fat-adapted as possible, but to get you fat-adapted enough to maximize performance, and avoid the pitfalls that being a “sugar burner” can bring. If you are already following a ketogenic diet, you might not recognize much change during this phase, which is intended to flip the metabolic switch towards burning fat as the primary fuel source. This switch is most quickly done by cutting the carbs so low that your body has no choice but to burn fat. Those coming from a ketogenic background will find this phase to be smooth sailing as you have already flipped the metabolic switch. For those folks, you can see this as matching your lifestyle intensities with your nutrition.
For those on this journey for the first time patience is key. My number one piece of advice is to avoid looking at all things you cannot have, but rather take advantage of the luxury we have in modern times by focusing on the vast array of options you can have that are a grocery store trip away. If you are looking for some great recipes that fit nicely within this phase’s framework I encourage you to check out the recipes in, The Primal Blueprint Cookbook , by Mark Sisson and Jennifer Meier, and/or The Art and Science of Low Carbohydrate Performance , by Dr. Jeff Volek and Dr. Stephen Phinney.
Regardless of whether this is your first attempt at strict keto, or a continuation of what you have done, this phase is coupled with recovery from your previous training cycle, and a gradual reintroduction of building a strong aerobic base. This is good practice for athletes of all disciplines as even building strength and power is better accomplished when a strong aerobic base is in place. The short and simple way of describing this phase is to match slow burn activities with slow burn fuel sources. Rest assured, you are providing your body with the framework to build from as you continue to progress.
Putting In the Time
As you find yourself developing along the aerobic framework and your training volume is beginning to reach its peak, you’ll find yourself with less time between workouts. Workouts are longer in duration, and in some cases with highly trained athletes, you are doing more than just one workout per day. Essentially, you are shortening the window of rest between efforts as your body becomes adapted and more resilient to the lower volume phase. This shorter window marks the time when you may find it useful to introduce a few more Primal approved carbohydrate sources. Relatively speaking, this is still quite low when compared to a high(er) carbohydrate approach. You will still gather a vast majority of your nutrition from fat.
Letting your body be your guide is very useful as you move into this phase. It is during this phase where I look for some telltale signs from my clients and myself. It’s okay to enter this phase following your strict ketogenic approach, but don’t be too bull-headed if you notice feeling flat or sluggish during workouts. When you start to notice that you are feeling a little flat, it’s a good sign that a small increase in Primal approved carbohydrates is wise. I recommend starting with small increments of reintroduction as a way to avoid going overboard.
A good rule of thumb is to start by shifting up your carbohydrate intake by five percent. If you notice that you feel stronger and more energetic during your workouts, you found the sweet spot. A little bit goes a long way during this phase, because a strong fat-burning engine has been built, and the addition of a small increase in carbohydrate will provide more bang for your buck when compared to a nutritional approach that is already heavily based in carbohydrates. Rest assured, you are not sabotaging the developed fat burning engine. A heavy reliance on fat is still in place here as the great majority of fuel you are giving your body is still coming from fat. Consider it optimizing.
Bringing In the Bang
With a very strong aerobic base thoroughly established, and the fat engine burning hot, it is time to sharpen the spear. Sharpening the spear is a phase in training I call, “unsustainable year round.” The reason for this is not because it is bad. It is simply a phase that will eventually require a mental and physical break to be able to do it again, and to continue to improve. It is a fun, but challenging phase of training, and I personally keep it enjoyable by stepping away from it at the end of a training cycle.
During this phase, since peak work is done to reach a goal, it also marks the phase of the cycle where the highest ratio of Primal approved carbohydrate sources is optimal. Similar to the last phase, it is not a drastic change, or a change that will sabotage the ability to turn to high reliance on fat as fuel, but rather taking advantage of the phase of the cycle where benefits from a fuel source that burns hot is present. I like to describe the carbohydrates in this phase as rocket fuel. A little bit goes a long way, and gives you a big punch, but going overboard can burn you up.
Similar to the previous phase, letting the body be the guide is a great starting point. If you notice a missing gear during intensity sessions, that’s the spot where a small increase of Primal approved carbohydrates is in order. Focusing on things like berries, melons, tubers, and raw honey are some “go to” options during this phase. Enjoying this phase as a way to broaden the range of food choices, or practice a couple different cooking recipes, is a good mindset during this phase.
Individual experiences will vary, but generally speaking, this phase can benefit from around twenty percent of your nutrition coming from Primal approved carbohydrates. Training volume can play a significant role, so if you’re following a program on the lower end of volume, less carbohydrates can be brought back. If this is the case (or prior experience would indicate adhering to a strict ketogenic approach has worked well), starting with small increments of carbohydrate reintroduction is the best plan of action. If that last gear isn’t coming back with small increments, continuing to add small amounts back is the next step.
A question or fear often expressed during this phase is losing fat burning potential. Remembering the goal here is important. This is not a phase that will be in place year round. A return to a stricter ketogenic approach is on the horizon. Even with the increase in carbohydrate, a high level of fat-burning is still necessary to meet your metabolic needs, because even at twenty percent carbohydrate the majority (60-70 percent) of nutrition is coming from fat.
Coupled with this, during this phase, being mindful of rest and recovery are important aspects. Challenging efforts need to be matched with proper rest and recovery. When programming training during this phase, it is routine to build in what is called de-load weeks. This is where approximately a week of reduced volume and intensity will give the body and mind a break—and the opportunity to grow and improve from all the hard work. This also provides the opportunity to scale back on carbohydrates for a week and return to the highest of fat burning states. During this phase when a de-load week is in session, dropping back to a more strict ketogenic nutrition plan is appropriate.
The Hay Is In the Barn
Once adequately peaked for an event, adventure, or fitness goal it is time to redirect priority from some of the hardest work to resting. This does not mean shutting things down altogether, but rather a reduction in the frequency of intensity sessions and volume. Similar to the de-load weeks, this affords the opportunity to scale down on carbohydrates. This also allows you to once again remind the body that fat is the primary fuel source.
This is the phase at which high carbohydrate folks will begin chatting about “carbo loading.” I find it fascinating how carbo loading has come to be defined in recent years. For many, this means a high carbohydrate diet is coupled with a barrage of even more carbohydrates the day or two before an event. For the fat-burning athlete, it looks different. The carbo loading practice is a week long process as opposed to a final excuse for gluttony. The first four to five days is met with strict ketogenic nutrition. Again, we are programming the body to burn high levels of fat.
One final nudge or reminder… When two days out from the event or adventure, a small reintroduction of carbohydrates will be adequate for your metabolic needs. The way to view these days is similar to the intensity phase of training. It is not full-fledged high carbohydrate, but rather more along the lines of approximately twenty percent of intake; similar to the intensity phase.
What you can expect within this framework is a much lower reliance of carbohydrates to fuel activities. In an event or adventure, this means the need to constantly bombard the digestive tract with frequent refeeds and engineered fuel will be minimized. My personal experience has been a reduction of at least fifty percent in competition fueling along with a much more stable flow of energy. The peaks and valleys experienced on a high carbohydrate approach are no longer a concern.
Thanks again to Zach Bitter for sharing his experience and expertise in today’s post. You can follow Zach on his blog  as well as his social media channels (Facebook , Instagram , Twitter,  and YouTube ).