Fat for fuel, my ketogenic diet experiment while endurance training.

What is a ketogenic diet?

The ketogenic diet is a high-fat, adequate-protein, low-carbohydrate diet. The diet forces the body to burn fats rather than carbohydrates. Normally, the carbohydrates contained in food are converted into glucose, which is then transported around the body and is particularly important in fuelling brain function. However, if there is very little carbohydrate in the diet, the liver converts fat into fatty acids and ketone bodies. The ketone bodies pass into the brain and replace glucose as an energy source. An elevated level of ketone bodies in the blood, is a state known as ketosis.

 The ketosis we're talking about is what Dr. Atkins refers to as "Benign Dietary Ketosis" (or BDK), and should never be confused with Acidosis — a dangerous state for diabetics and those in advanced starvation where acetone builds in the blood and tissues. People will sometimes tell you that producing ketones is dangerous for the body. This is simply misinformation. They're confusing ketosis (the state from a ketogenic diet) with ketoacidosis (or acidosis) which occurs in uncontrolled diabetes and/or starvation.

 The ketogenic diet has been around for a long time. A quick google search will reveal that the ketogenic diet was introduced by modern physicians as a treatment for epilepsy in the 1920s. For two decades this therapy was widely used, but with the modern era of antiepileptic drug treatment its use declined dramatically. By the end of the twentieth century this therapy was available in only a small number of children's hospitals. Over the past 15 years, there has been an explosion in the use, and scientific interest in the "keto" diet. Remarkable studies are showing great promise by using the keto diet in the treatment of alzheimers, cancer, diabetes and obesity. Outside of the medical community, natural bodybuilders use it to shred that last little bit of fat and add a bit of bulk. Endurance athletes are using the keto diet to make the body as efficient as possible at burning fat for fuel or as they say "becoming fat adapted" so they can stretch out their stores of glucose a little longer.

 A fat adapted person is said to have a body that prefers fat as a fuel and can therefore have some carbohydrates and not fall out of ketosis (stop burning fat for fuel). The fat adapted person will be constantly burning either dietary fat or body fat around the clock. When sugar is eaten in any of it's various forms the fat adapted person will use some of the sugar, store some of it in various organs and then continue right on burning fat for fuel because it is the new preferred fuel of the body.

My early exposure to using fat as a fuel

Using fat as a fuel for endurance athletes has been a mild interest of mine since very early in my running. When I was training for my first marathon (SF 2012) I read an article about "depletion runs" aka "starvation runs". To put it simply you run a long slow run without any fuel at all in your system so as to force the body into using body fat as a fuel. Apparently these types of runs will help your body become use to and more efficient at burning fat as a fuel. When people talk about "bonking" or "hitting the wall" they are talking about running out of sugars to fuel the effort. The body then has to go through a "rough patch" while it is, in simple terms, switching from mostly sugar to mostly fat as it's fuel source. My goal for quite some time now has been to limit my bodies dependency on sugar and to lessen the harshness of these "rough patches". The depletion runs did just that. When I did these runs it was very predictable for me to hit a rough patch at 7 to 9 miles. I would feel a wave of nausea but I could somehow deal with it better and better as I did these runs. Although I didn't know the name of it at the time, I was likely in a state of ketosis.


How about less of this and a better performance?

As all runners can attest, the #1 topic of longest distance running is food. Specifically what to eat before, during & after a run. The most common advice is to carbo load the night prior to a big effort (relative to the individual) so as to load up on sugars. Then in the morning top off the tank with more carbs  just a short time prior to running the big effort. During the run you are suppose to take sugars in to help stretch out the supply you created earlier, most of this comes from sports drinks and sports gels. All of this carbohydrate eating is intended to stave off the inevitable "bonk" which in marathoners comes somewhere around mile 18 to 20 give or take. The trouble with carbo loading is in knowing how many sugars to take in. After you have used some and stored some sugars, what will the body do with the rest? Store them to fat for later use. LATER USE??? The trouble with this is that we rarely ever let our carbohydrate intake get so low for a long enough period of time so as to encourage the body to burn these excess stores of fat. This is where the depletion runs came into play for me, long before I knew anything about ketosis. I did these types of runs to specifically force my body into using fat for fuel and burn up these excess stores of fat. I was also trying to reduce the duration and intensity of the fuel switch over. By lessening my need for sugar I also hoped to shorten the length of time I spent at ultramarathon aid stations (aka trail buffets). If I don't need a lot I can just grab and go, saving tons of time.

How I found and researched the ketogenic diet.

 About a month or so ago I got hooked on listening to health & fitness podcasts (read the article). Especially Ben Greenfields two shows, The Ben Greenfield Fitness Podcast & Endurance Planet, which are all about endurance training and sports nutrition. Ben talks a lot about being in a state of ketosis on his ketogenic diet. Which he is using to get in shape for his Ironman Canada event. Ketosis is the opposite of Glycolysis which is what most endurance athletes swear by. Ketosis is the breakdown of fat for fuel and Glycolysis is the breakdown of sugar for fuel. By listening to Ben and his podcasts I learned a lot, discovered more podcasters and consequently heard more proponents of this low carb "keto diet". This diet would allow me to stay full or "satiated" because of the high fat content I would be consuming. Hunger is obviously the feeling that leads us to feed and that usually involves carbs. I could more easily avoid carbs if I wasn't hungry. Awesome!


 Articles like this and this are all over the web telling the reader all about the diet and how amazing the diet is. Videos are all over Youtube.com like the one to the right and as I mentioned, it's been a hot topic on a ton of podcasts. Those videos I watched and podcasts I listened to led me to Dave Asprey. Dave is the founder of "bulletproofexec.com" where he promotes his bulletproof diet among other "bulletproof methods" for optimizing your life. His bulletproof diet (aka Upgraded Paleo) calls for you to be in ketosis at least once a week and his diet highly favors fats (specifically the short & medium chain triglycerides). His recipe for making bulletproof coffee will get you into ketosis pretty quickly if it is combined with intermittent fasting (skipping lunch until early afternoon). The theory behind this is that you wake up in the morning in a semi fasted state and likely burning fat as a fuel. By starting your day off without carbs of any kind and only taking in the special fats that are added to the coffee you stay in this fat burning mode. By the time your GI tract has dealt with those fats from the coffee, and it will immediately do so due to the very kind of fats you ingested, your body will then begin to metabolize body fat for fuel and you won't feel this switch over. It worked for me. By the time I finished my coffee it was hours before I needed food. For variety on some mornings I would fry 2 farm fresh eggs in grass fed butter and that is classic paleo and definetly keto style. As you become more "fat adapted" you can bring some carbs back like adding more vegetables throughout the week. Eventually you will be able to eat fruit. The point of all of this is to teach the body to use fat as a fuel and to burn sugar when necessary but always switch back to fat as a primary source. Right now most people are sugar burners and shortly after a sugar burner eats he feels hungry again. If you were a frutarian or an 80/10/10 vegan you will never give your GI tract a break! If you find yourself reaching for food or even small bites every few hours you are likely having blood sugar spikes and drops that are prompting you to eat.

Starting off on a ketogenic diet.

I already ate a paleo style diet whereby I avoided grains and sugars (unless I was working out) but did not limit my fruit & vegetables to any large degree. I ate high amounts of protein and ate moderate amounts of fats. All I really needed to do was up my fat intake and lower my protein. That's as simple as adding grass fed butter and coconut oil to whatever you can and also cooking with these fats more often. I started off by trying the bulletproof coffee. Tons of fat and no protein. Ta daaaahhh! My ratio of fat to protein for the day just flipped. As for the taste, WOW. It is super tasty and on day one I took a large travel mug of it to work. No breakfast. No food since dinner last night. This meant that I was in a fasted state and likely burning fat for what little fuel I needed when I woke up. The high fat content of the coffee kept me very satiated and exceptionally alert for around 7 hours!!! I admit it is a big travel mug of coffee. Almost half a pot of coffee fits in there but I swear I didn't once think about food. A handful of mixed nuts around 2pm was all I ate and at 4pm I was on my way home and food still had not really occurred to me. My blood sugar had never spiked all day so it conversely never got low either. I just burnt dietary fat and some body fat for fuel and felt absolutely fine. By 5pm I was out the door for a 6 miler through the hills and all I brought with me was water. When I finished the run I was stunned. I wasn't hungry at all. I felt fine. No brain fog, no headache, no pit in my stomach because no Ghrelin hormone had been released.

 Ghrelin is the opposite hormone of Leptin. Leptin tells your brain when you are satiated and Ghrelin tells you that it is time to fuel. My body had fat as a fuel so it was feeding, hence I was not starving (figuratively and literally) at all. Dinner brought the first sugars of the day in the form of vegetables. My system must have switched from fat burning mode to sugar burning because a little while after dinner I found myself hungry again meaning my blood sugar likely spiked and eventually fell because of the vegetables. I made sure to snack on healthy fats to get over my hunger cravings by eating things like almonds, olives and cheese. The rest of the week went exactly the same with slight variations in the hungry feeling after dinner, but the sensation of hunger never hit any other time no matter the days activities including my workouts. I realized that the lower intake of food meant less nutrients in my body. I made sure to double up my daily multivitamin and my fish oil intake just to be safe.

Ketosis and running: The initial experiment

 I woke up early the first Saturday morning and prepared my coffee. I drank about a quarter of it while I got ready to run. I took it with me on my drive to the Santa Cruz mountains and got a bit more of the fat in me. I ran 13 miles with over 2000' of elevation gain and had no lack of energy climbing 90% of that in one long 5mile section! Seriously! When I got home and realized I wasn't all that hungry I was stunned. Dinner again brought the first carbs and again I had hunger after dinner. Sunday's run was an exact repeat of Saturday's run. This proved I could do back to back 13 mile hard runs with nothing but fat as my fuel! The week topped out at 46 miles. The next week was a repeat of the first week but I did 19 miles on Saturday and 11 miles on Sunday ending the week with 51 miles. How far could I take this new endurance fuel? The following Saturday I raced as hard as I could over that half marathon course I had been practicing on from before. It was the Crystal Springs Half Marathon  from Coastal Trail Runs. I was very satisfied with my 2:03:00 time (5th in my age) and my ability to perform at my maximum on nothing more than fat (read about it here). I topped the weekend off with a 5 mile recovery run giving me 36 miles for the week which is pretty good for a race week that is supposed to be full of short distance shake out runs. I was taking in very little carbs and feeling great both in terms of hunger and in my running performance.

Am I really burning fat for fuel?

 At this point in the diet I was convinced that I was on the right track. My body could put out fairly hard efforts, whether they were long and slow or full throttle race days, on fat alone.  I didn't have a lot of excess weight on me to lose (anymore) but I wouldn't mind lowering my body fat percentage and getting a bit more lean and that was happening. My weight was staying steady (maybe lost a couple pounds) but my abs were showing more and my pants were a bit more loose. Now that I was a month or more into this diet I wanted to know if I was doing it right. I wanted a way to gauge my efforts. I searched for articles on how to know if I was fat adapted and from what I read, I was. If you can do the type of workouts I was doing without any trouble and if you frequently "forget" to eat because your body didn't scream at you, you are likely fat adapted. I searched for articles on how to know if I was in ketosis or in other words, was I really burning fat for fuel and thus having ketone bodies in my blood. In comes the Keto Stix. These are a simple litmus style paper strip that you urinate on to test for the presence of ketones. You can buy them from any pharmacy. Most stores keep them behind the glass so you will need to ask for them. I have seen them sold for $7 at Wal-Mart and $17 at CVS. I tested every time I could and most often I would be at the very lowest end of ketosis or more specifically I had "trace" amounts of ketones in my urine. I would test negative quite a bit too which is perfectly fine. You only "need" to be in ketosis once a week according to Dave Asprey. I later read that these test strips are not effective for a fat adapted person. That is why I constantly hung around the low end of the color spectrum. At first your body is not use to this new fuel and burns these Ketones inefficiently. What is not burnt or partially burnt is excreted through the urine and that is what the test strip picks up on. If you are fat adapted, or if you have been known to do some depleted workouts your body is likely using almost all of the ketones present in the blood. You are not spilling out the excess, therefore it appears you are not in a state of ketosis. The only way a fat adapted person will know if they are in ketosis is to use a blood monitor. These devices are very similar to a blood glucose meter whereby a small droplet of blood is placed on a strip and read by a handheld device. The device is relatively inexpensive (<$50) but the test strips can be quit pricey (+/- $5 per strip!). I did not buy one. At least not yet ;-)


Ketosis and long, hard runs: How far can I go on fat alone?

 The next big test for this diet was to do a really long and hard run, relative to my recent runs. That ended up being a 22 mile run in a specifically depleted state. I wanted to be sure that fat was the main fuel at work here so I very purposefully avoided all carbs for the week being especially mindful on Thursday & Friday. I was certain that I had not ingested so much as a baby carrot worth of carbs in 2 days and woke on Saturday morning with my usual bulletproof coffee. I wanted to get out the door by 8am so I could be cleaned up and ready for the day by noon. My wife had a big day (& night) planned with her girlfriends so me and the baby would be rollin solo for awhile. I only got a little coffee in me before it was time to hit the sidewalk. I decided to fill my 10oz handheld with the brew and head out with it in my left hand and my 20 oz bottle filled with ice water straped around my waist. Did I mention earlier that this coffee is tasty. I drank most of the coffee by mile 6 or so but it did get cold and I was sloshing it around so much that I was afraid I would churn the oils back to a butter so I dumped that last bit. My water bottle lasted me until mile 15 or so where I stopped and bought some ice water at a gas station soda fountain. The last 7 miles are brutally hilly compared to the pancake flat 15 miles  thus far. I wondered how my energy stores would hold up.

Burn more fat at conversation pace!

 I pushed hard and ran (slowly) up the first 1000 ft or so but after that the hills grew steeper and I began to walk. The sun was rising high by now and my sweat rate was a thunderstorm. I emptied my bottle and filled it at the top of the first big climb and again 2 miles later. Lucky for me the water fountains are plentiful in this area. The downhills became as hard as the uphills and I started walking those too. Over the next 2 miles of trails through 2 different parks I had very little flat so I walked most of those trails. After that I had a 2 mile flat road run home that ended up being a death march. I had walked at least 3 miles cumulatively up to this point and I was not rebounding. My legs were dead, my head was foggy and my stomach was sour. I walked those last 2 road miles to home. At times I was leaning on trees trying to hold back puke while debating the merits of just letting it fly. This unfortunate turn of events came on swift and brutal. I passed a hospital on my way home and seriously debated going in. I couldn't. My wife was at home and ready to hit the town for the first time in a long, long time. I can't let her down. I stared at the 5 ft in front of me and put one foot in front of the other and willed myself home. I was literally weaving like a drunk as I walked and I knew I was really, really bad off. I tried to drink water but it only soured my stomach. I tried to dump it over my head for heat relief and that was somewhat effective. I staggered through my front door at 10 minutes to noon and quickly began remedying this situation. I hit the showers while Mary made a fruit smoothie with yogurt and milk, ingredients I would normally skip. I wanted the dairy fats to slow the digestion of the sugars from the fruit so I could in effect create a slow drip of sugar into my system. I took down a Sprite after that ( left over from company earlier in the week) and within an hour I was back from the dead. This was a disastrous run that taught me a lesson. Fat alone is only good for shorter or easier runs but the longer you plan to be out the more sugar becomes an unavoidable part of the equation.

 Further reading in the days that followed and a fair amount of reflection left me concluding that really long runs with big hills will always need some carbs. Carbo loading and carb breakfasts may not be necessary but a bottle of quality sports drink and an occasional gel seem to be unavoidable on runs of 3 hours or more. I used a keto stick after regaining my marbles that day and I was deep into ketosis. My stick turned dark plum color and on that color chart plum indicates the highest concentration of ketones in the body. From what I have read, testing in the darkest purple range is usually a sign of dehydration -- the urine is too concentrated.

The future of my ketosis experiments.

 The next evolution in this process will be to see how much sugar I need to fuel a long run. I already know that I need almost none to get by day to day and that includes my weekday runs but it is also clear that I need some amount of sugar on my long runs. I just need to figure out how much. One idea I am toying with is using Ben Greenfield's Endurance Pack. The Endurance Pack is for optimizing workouts of 2+ hours while keeping the body in maximum fat burning mode and reducing intake of high sugar and high caffeine compounds. The Pack contains UCAN Superstarch, X2Performance, a bottle of MAP (Master Amino Pattern), and an option to add-on VESPA (Timothy Olsons fuel)ultra-concentrate wasp extract. This is enough for up to several months of training and racing. It better last 6 months, if not longer because it is not cheap ($320)!! Who knows if I will get into this many supplements. For now I will experiment with various amounts of sugar to see what is optimal for me and then if I want to dial it in further I will switch from those sugars to the Endurance Pack (maybe???)

The Ketogenic Diet Conclusion:

This is (for me) a great diet. I'm not eating sugar (poison) and I am not hungry. Two things that make diets a pain in the butt. I burn excess fat stores easily and maintain my weight easily. I take in a good amount of healthy fats, grass fed proteins, vegetables with a little fruit every once in awhile. I am encouraged to have 1 higher carb day per week and if I completely go buck wild I will not gain weight like I use to as my body will go back to burning fat quit easily. I have trained my body to fuel itself the way I believe we were meant to as a species. It's tasty, easy and effective. I plan to stick with this for quite sometime exploring the limits of fat as a fuel and will report back here periodically. Stay tuned!

My Ketogenic Christmas gift and Coffee Recipe