Not intended as medical advice, please consult with a doctor before starting any new diet.
THE VIKING MANIFESTO: Piecing Together a New Approach to Nutrition and Training for Swimmers from Scientific and Anecdotal Evidence.
Part 3: LCHF and Aerobic Capacity
In part 1 I gave you a summary of some general nutrition advice that seems to contradict most of what we have been taught all our lives. In part 2 I laid out some of the science of swim training in relation to the energy zone descriptions recommended by USA Swimming. This time, it starts to become about how a low-carb, high-fat LCHF diet matters to you, the swimmer or swim coach.
When I first started burrowing down the rabbit hole on this topic I saw unbelievable pictures of overweight and obese people who said they had tried everything and this was the first thing that ever worked to help them lose weight and keep it off. I saw a lot of posts from body-builders who claimed they could gain muscle and get lean by eating fat. I saw a lot of pictures of bro’s from the gym showing off their progress and heard lots of stories about how everyone else at the gym (as well as their doctors) thought they were idiots until the progress in body composition and lipid profiles were obvious. The anecdotal evidence was overwhelming, and the science they presented and dissected was fascinating.
Then I stumbled across this guy: Dr. Peter Attia was a boxer who roomed with a swimmer at Stanford during medical school. He fell in love with swimming and started training for triathlons and open water swims, and writes an absolutely obsessive blog about his quest to stay in near permanent ketosis. He is also one of the founders of NUSI, an organization determined to perform a lot of the studies to answer nutrition questions no one has attempted before. There’s a lot of bad science out there and he wants to do something about it. Watch this video of Dr. Attia to learn more than you ever wanted to know about the ketogenic diet.
Go ahead, search for LCHF and/or ketogenic triathletes and runners on the google. Come back when your mind is blown. Swimming is way behind the times when it comes to stuffing our faces properly.
During the height of the Atkins phase there were probably a lot of active people who jumped on board the low carb bandwagon and within a few weeks decided that it was a horrible idea for athletes. This is due to two things: first, when reducing carbohydrate we stop retaining the same amount of water, which means that we also flush electrolytes and can end up with flu-like symptoms if we do not manage this correctly; and second, there is an adaptation time that is required to start seeing the benefits of burning fat as your primary fuel. As a sugar-burner, I did not use fat as a fuel as efficiently, but now that I am a fat-burner I still have no problem burning sugar as fuel any time with no adaptation time required. You see, there are changes that need to happen within the muscle, within cells, to be able to efficiently burn fat and ketones as fuel. Reducing carbohydrate allows us to take better advantage of a higher level of metabolic flexibility.
Part of the problem with the currently accepted science regarding athletic nutrition is that when it comes to any studies that measure whether carbohydrate or fat is a better source of energy, fat tends to be set up to fail. Studies can claim to be low carb while still allowing up to 30-50% of energy intake as carbohydrate (since the standard diet contains a ridiculous 70% carbs,) which does not allow for the metabolic switch to be flipped properly. It can actually be a recipe for disaster in health since a diet that is both high carb and high fat has proven to be the best way to develop heart disease, especially when much of the fat in the standard American diet is from easily oxidized polyunsaturated vegetable oils or trans fats. Also, very few studies have been done that have allowed proper time to adapt and gain the metabolic flexibility to truly find the answers to many of the most important questions related to sports performance. Most of the studies out there would seem to imply that carbohydrates are not just a superior fuel, but that cutting them out is guaranteed to make performance suffer. Unfortunately, the textbooks tend to agree.
Ever heard of Dr Tim Noakes? He wrote a book called The Lore of Running and there are virtually zero serious runners out there who have never read it. He was a world-class endurance runner in his day and is one of the leading researchers in athletics. He is one of the guys who helped make “carbohydrate loading” a well known concept, among many other very important areas of research in which he has been a respected leader. Recently, Dr. Noakes has taken some heat for changing his mind in a big way. He is now telling people “If you’ve got Lore of Running, tear out the section on nutrition.” He now endorses a low carb, high fat diet. It takes a big man to admit you were wrong, but this guy followed modern research and came to the conclusion that we should all be eating fat rather than carbohydrate as our primary fuel, and as outlined in part 1 of my series, it is not just for sports. It is for digestive, cardiovascular and neurological health as well.
Remember, moving anaerobic threshold and VO2 max up the hill has been the main focus of most traditional swim training for decades. The majority of the work we have always done is in the EN1/2/3 boxes on the chart and is done with the hope of improving blood flow capacity and mitochondrial density. Basically, we want to supply more fuel through efficient blood supply and provide more receptors through which to burn it. Here are some additional details on VO2 max from sport-fitness advisor, and if you visit the website it links to additional sources as well:
The fitter an individual is to begin with, the less potential there is for an increase (in VO2 Max) and most elite athletes hit this peak early in their career. There also seems to be a genetic upper limit beyond which, further increases in either intensity or volume have no effect on aerobic power. This upper limit is thought to be reached within 8 to 18 months.
Crucially, once a plateau in VO2 max has been reached further improvements in performance are still seen with training. This is because the athlete is able to perform at a higher percentage of their VO2 max for prolonged periods. Two major reasons for this are improvements in anaerobic threshold and running economy.
So basically, once you hit your “genetic cap” for VO2 max, most improvements you see beyond that have more to do with technique efficiency and with being able to improve the anaerobic threshold to spend more time at an intensity level close to that max without locking up due to generating lactate above what you can clear. This is important to understand in regard to training. Basically, VO2 max is a measurement of potential, but anaerobic threshold tells us how much of that potential we can effectively apply to endurance racing.
Remember Dr. Attia from above? Well, when he started his blog, he posted this about the benefits he has seen since switching to a ketogenic diet. Keep in mind, this is a doctor who was well-trained in endurance sports and had been meticulously tracking his stats before he switched his meal plan. This is not your mom trying her first “couch to 5k.” Note the improvements at the first three levels, which are the most pertinent to aerobic training in light of the information given above.
Part of the reason for these advances might be that the ketogenic diet brings on a “glucose sparing” effect, meaning that even though a person might be training to prime their muscles to burn fat, and are probably storing less glycogen in the muscles and liver because of the carbohydrate restriction involved, we can use so much less glucose while racing that we still have it there for that max power at the end of the race when we need it. To fully appreciate that this might be possible, I need to introduce you to the concept of Respiratory Quotient, or RQ. I have cut and pasted the description from Dr Attia’s website, as I contend that this is quite possibly more important to endurance training than VO2 max:
The respiratory quotient, or RQ, is simply the ratio of carbon dioxide you produce to oxygen you consume. This ratio typically varies from about 0.70 to just over 1.00. Why it’s important and helpful to know this ratio is that you can infer, based on the ratio, what you are utilizing for energy (i.e., how much fat versus glycogen) at any point in time during the test:
- When RQ is 0.70 (i.e., when you breathing out 70% as much carbon dioxide as you are consuming oxygen), you are effectively getting all of your energy from fat.
- When RQ is 1.00 (i.e., when you are breathing out an equal amount of carbon dioxide to the amount of oxygen you consume), you are effectively getting all of your energy from glycogen.
The goal of any endurance athlete is to derive as much energy as possible from fat, rather than glycogen, for a given level of exertion. Why? We can store about 1,200 to 1,600 calories worth of glycogen versus 100,000 calories of fat. Furthermore, replacing glycogen during training/competing is full of problems. Hence, you want to “spare” glycogen for only those times when it is essential (i.e., when you are anaerobically active) and use fat as much as possible when you can afford to (i.e., when you are aerobically active).
The implications for improving our RQ score should seem obvious for distance swimming and endurance training, since relying less on glucose for work at the same intensity could be tremendously valuable. This can help an athlete to work harder with less contribution from anaerobic glycolysis, and may have something to do with the claims of “never bonking,” better lactate clearance, and better recovery that many low-carb athletes swear by. Take a look at Dr Attia’s chart again– it is obvious that his aerobic capacity went up, and that he was generating the same power/intensity while using significantly less glucose. Essentially, he moved his anaerobic threshold, and can spend more time closer to his VO2 max, by manipulating his diet with no other changes. Remember, he was already well-trained, and then made these improvements completely as a dietary experiment.
Dr. Attia gives us a great N=1 experiment, but other studies out there show that his increase in aerobic capacity and improved RQ are not an anomaly. As a matter of fact, recent studies that have allowed for adaptation time and that have finally been done with well-trained athletes are confirming new benefits that long time low carbers have been bragging about for decades. The science is slowly catching up. The hardest part for me to swallow about all of this when I began following the evidence was that most of us swimmers are not ultra-endurance racers. Improving low intensity endurance isn’t really that appealing to me as I don’t intend to ever race a mile again in my life– and you couldn’t make me race a 10k even if it were to escape the zombie apocalypse.
For this to apply to us 1-2 minute racers, we would still have to be able to show that adaptation to a ketogenic diet will matter at much higher intensities, those that are owned by anaerobic glycolysis, or it just won’t apply to racing all that well. Right?
Enter the UCONN study. Ben Greenfield is another self-experimenter. He and a few other hardcore triathletes teamed up with a leading researcher, Dr Jeff Volek at the UCONN Human Performance Laboratory. They decided to test a whole bunch of stuff to see what changed when extremely fit athletes were given at least 6 months to adapt to a ketogenic diet, which is much longer than most previous studies had ever done. If you read part 1 and part 2 of Ben’s write up, you will see that they blew some of their stats off the charts. The most important of those has to do with how quickly we can metabolize fat as a fuel during exercise.
It has been standard thinking for decades that fatty acids could only be burned at a maximum rate of about 1g/min. That was with research done with athletes though, who were not adapted to the LCHF diet. At that rate, even with the ability to generate so much ATP from fat versus the tiny amounts from glucose that I outlined in the last chapter of my manifesto, the trade off was not good compared to glucose which generates much less but at a much higher rate, unless of course you are only focusing on lower intensity activity. The study at UCONN demonstrated that when well-trained athletes are given enough time to adapt to a ketogenic diet, that rate can improve to levels far beyond what we thought possible. As a matter of fact, all of the athletes in the study were above 1g/min for the majority of the study, and some reached peak fat-burning above 1.5 times faster than what we previously thought was the maximum possible. This is an incredible finding and has tremendous implications for endurance sports.
So waitaminnit?!… you mean that we generate significantly more ATP from burning fats than we do from burning carbs, and by simply choosing to skip the hashbrowns when I order my steak and eggs I can make fat burn 50% faster?! Yup. That’s what I am saying. Why in the hell would we want athletes in an endurance sport to be tethered to a carbohydrate burning system that is really only intended to help us with the kick at the end? Yeah… We have been doing it wrong for a long time, guys. Follow the science. Much more on this later.
To summarize: there is evidence that the LCHF diet enhances some of the most important adaptations that swimmers strive to maximize during aerobic endurance training. By priming the body to more efficiently use fat as a fuel for aerobic workload, we can generate more power aerobically, reduce the required contribution from anaerobic glycolysis, spare glycogen for later in a race where it can play a more important supplemental role, and tap into a nearly unlimited fuel tank of stored fat when compared to the small amount of glucose we are able to store in the liver and muscles.
Let that sink in for a bit… you’re gonna need to swallow that bite before I make my next post.
The Viking is a delusional swim blogger who has made a commitment to train for the next sixty years to breaking every masters swimming record in the 100-104 age group. Watch for his masterpiece, “A Completely Made-Up History of Competitive Swimming” to hit bookshelves soon. This series is being published concurrently on SwimSwam and SwimBrief.net.