This is another guest post from Bahrain-based endurance athlete Phil Solarski, who I coached full time for a year and now coach on a consultation basis. Upon working together, Phil made a success debut in triathlon (short and long course) and he broke three hours in the marathon—all after recovering from overtraining before we began work together. He’s very in tune with proper diet, fat-adaptation, and MAF, using all these tactics to enhance his performance and ensure health. Thus, I thought his latest keto marathon tale is a great case study to highlight!
While a case study is just an n=1 scenario, we still don’t know a ton about nutritional ketosis for athletes in training, thus I am always willing to read and share someone’s experience.
After Phil’s account, I added my concluding thoughts of how I would approach the diet situation differently, plus I cite some research to back my ideas.
Lastly, several key points I need to make:
- The marathon is a tricky distance—while clearly an endurance event that requires aerobic fitness and the fat oxidation (even sugar burners will burn some fat), glycogen still usually plays an important role in marathon performance for many if not most athletes.
- Phil still did perform incredibly well in the race despite the diet backfiring so let’s give a round of applause.
- This was not a scientific study so we cannot be 100 percent certain that the diet experiment was the main negative factor that held him back from his perfect race, but from Phil’s account he feels certain that the lingering effect of keto left a mark.
- This post is not meant to knock going low carb to be a better fat burner, but rather show that there may be a better way and planning it is key.
Without further ado, Phil’s keto marathon story…
Going Keto During Training
I’ve been in contact with Tawnee since 2014, when she helped my transition from overtrained runner to successful triathlete using MAF-based principles and I also finally broke three hours in the marathon. I am 38 and my MAF HR is 139. I live in Bahrain and the weather in the summer is unforgiving, with temperatures well over 100 deegree Fahrenheit almost daily. Any serious training can only take place from October to April each year.
So in October 2016 I started training for the Dubai Marathon with a view to qualify for Boston in 2018. I was confident of making the time of 3:10 having already achieved a 2:59 at London in April 2016.
The first few weeks of training were all MAF-based. I started introducing some tempo runs in November and soon improved my MAF pace from 9 to 8:15 min/mile on around 60 miles per week.
By December I was hitting 100 mpw and running twice a day on many days. Christmas and New Year were a lesson in restraint as I aimed to keep the weight off and volume high. Three days before the Bahrain Half Marathon, my last tune-up race, I completed a routine set of intervals. As I was running home, I felt a twinge in my right quad. I tried to run the next day and could not, so rested. I ended up running a 1:26 and could have gone faster if it were not for my quad hurting.
I decided to cut back on running due to the niggle and also got the idea to try out a different dietary strategy with two weeks before the big race. Also, volume was already decreasing due to the taper. The idea: cut carbs and go keto to really dial in fat burning. I’ve gone keto before so I have been through the process, plus carb depletion is a tactic used by some elite marathon runners in the lead up to the event with the idea to train the body to use fat for fuel by reducing carb intake whilst increasing dietary fat and maintaining protein. I’m usually quite low carb as it is, consuming around 100g per day during peak training. This is more than enough to sustain energy on long runs and interval sessions. But in this experiment, I dropped my carb intake down to 20-30g per day for 10 days to get into nutritional ketosis.
With the running I still was able to do, I noticed some negative changes. My interval sessions and tempo runs became much harder, RPE, pace and HR all increased. My tempo pace increased from 6:40 to 7:10, and I would be shattered by the end of the session. My MAF pace also increased from 7:50 to 8:20, and resting heart rate rose from 45 to 55. My recovery was not ideal and HRV plummeted. Nevertheless, I stuck with the plan.
Three days before the race I started carb loading with lower-GI carbs like sweet potatoes and white rice, and I felt back to full energy again. But perhaps the damage was done.
The race itself went well enough. After going through halfway in 1:29, I ran out of gas in the last 5km and managed a 3:01. I’m sure that the keto experiment affected my pace, as I was not as well recovered, and the few days of “carb loading” were not enough to make up for the depletion and effects of going keto in the midst of those final training days. It’s worth noting, another factor on race day was the 75F heat and high humidity in Dubai. Fortunately, my quad was not a factor; it was fine during the race.
I truly feel that ketosis ruined my key training sessions in those final days before the race by jacking up my heart rate and it seemed to affect my recovery and HRV negatively—and that played into race performance since there was not enough time to “rebound” from those negative outcomes. I’m still keen on trying ketosis off-season as it helps me focus in other areas of life. However, I would not recommend it when in peak training for an A-race. Next time I would go low-carb (but not keto) for 5-7 days to fine-tune the fat burning, then do a moderate carb load 2-3 days prior to the event to restock muscle glycogen. I’m confident that I’d still be fat adapted and would not lose it with bringing back in some carbs pre event.
Next step, Boston 2018!
Tawnee here again.
Thank you Phil for sharing. I love when we can talk about the tough times and not just highlight when things go perfectly. Although, running 3:01 is hardly that tough of an outcome 😉
So what could Phil have done differently? Well he already stated the answer in the last paragraph, but I’d like to share more details, my thoughts and some research on this…
We know it takes at least 2-4 weeks to adapt to low carb and get through the “keto flu.” Phil knows this; he’s been through it before. So you really don’t want to be taking that on in the midst of a training-taper-race phase. In his defense, however, he was just trying to “hone in” on his fat-adaptation a few days prior to his race not a diet overhaul (the strategy of carb depletion followed by a brief carb refuel is like classic supercompensation, which is well established in the research and sports nutrition; however, he took it a bit extreme by going to a level of keto while still having key workouts to complete). But you can see that even dropping below 100 grams of carbs a day while still training—from low carb to very low carb—can have exponential deleterious effects.
If you’re doing an acute bout of keto, as Phil did, the short-term carb restriction will certainly compromise muscle glycogen stores and affect other biomarkers (like HRV and RHR as we saw with Phil). But what if you’ve been low carb for a while and you’re adapted and are past the flu? With long-term keto, like those in the FASTER study, glycogen levels in muscle and the liver may or may not be compromised but “the athlete will likely lack the metabolic machinery needed to fully use them as fuel sources” (1).
What could he do instead? You guys know I’m very careful about recommending low-carb and keto diets, and if you’re a female you can ignore this advice because I don’t like keto at all for gals. That said, I know Phil very well and he is a guy for whom I WOULD suggest doing phases of nutritional ketosis, but only doing it at very specific times in the year. In this case, I’d suggest he only go very low carb and/or keto in the offseason when training volume and intensity are low or nonexistent; this way he can really dial in fat-adaptation and metabolic flexibility, without the added stress of training or racing factoring in. I think he already realized this as well as he said ☺
It’s really hard and risky to maintain very low carb and/or keto diets when training volume and/or intensity are high—we see this anecdotally and also in the research. A recent study on world-class race walkers showed an impairment on performance when taking on keto amidst intense training; subjects underwent three weeks of a LCHF (keto) diet during intense training and the LCHF diet negated performance benefits due to decreased exercise economy (2). It can be argued that three weeks was too short of a time frame to effectively adapt and see the performance gains, but the bigger issue in my opinion was having these world-class athletes suddenly go keto in the midst of a high-intensity training phase! That’s just asking for a negative outcome. Don’t get me wrong, I’m really glad they did this study because it shows that if you do want to go low carb and get really fat-adapted, don’t do it in the middle of a training block. Instead, periodize your nutrition with your training and save the low-carb fat-adaptation phase for your offseason or when training is mellow. If the idea of nutrition periodization is confusing to you, ask questions, I’m happy to help!
Bottom line:
Build your mega fat-adaptation in the offseason or when training is low and maybe even stay semi-low carb ish into preseason if health and other biomarkers/variables check out (e.g. good recovery, good energy, and good performance beyond workouts). Ladies, for those in adequate health, you can do this too and just remember, whether male or female, you don’t have to go keto to get fat-adapted; all it takes is moderate low carb (probably some carb cycling), proper timing and quality nutrition choices.
Then as training and racing ramp up, ADD BACK CARBS STRATEGICALLY! During peak training and racing, don’t even worry about ketones or obsessing over sticking to less than 50 grams of carbs a day. If healthy carbs are used with proper timing, you will get the best of both worlds, fat-burning and glycogen replenishment (among other benefits of these macros), even if carbs get up to 200 grams on some days… Yup, you can eat that many carbs and still burn a lot of fat for fuel—if your training requires it and you’ve developed good bat-burning in the first place. If you leave out the carbs you will burn a lot of fat, but it will likely reach a point of diminishing returns with your performance and health. I see it all the time.
A recent article in the Strength and Conditioning Journal supports this approach, “One approach to maintain metabolic flexibility could include the ‘periodization’ of macronutrients based on the given training phase. For example, an athlete might use a KD for several weeks during the off-season, and then switch back to normal CHO consumption before competition” (1).
Furthermore, “although ketone bodies may serve as a substitute for CHO, they may also paradoxically reduce endogenous CHO availability through inhibition of hepatic glucose output, therefore lowering the capacity to sustain higher intensity efforts” (1). And in my opinion, the marathon, especially at heart rates exceeding 170, is high intensity even if it is an aerobic-based event.
Resources
2. http://onlinelibrary.wiley.com/doi/10.1113/JP273230/abstract