Tag Archives: endurance

Burn Fat for Fuel | The Paleo Diet

The marathon and triathlon seasons are fully underway and this year over half a million people will complete the marathon and thousands more participate in triathlons and other endurance events. Whether they’re entering an event for the first time or trying to achieve a personal best time, one of the most common questions I get asked by clients is “what should I eat before my long run?” The answer may surprise you!

A common refrain amongst most endurance coaches is that you must consume a heavy carbohydrate meal before your long run or bike to perform your best. High carbohydrate breakfasts of oatmeal, cereals, and juice or the classic ‘carb-load’ pasta dinner are staple recommendations from many top endurance coaches. While this is certainly not bad advice, there is another option.

Don’t eat any carbs before your long run or ride! (Yes, you heard me correctly.)

Let’s take a moment for a quick physiology review. When carbohydrates are ingested they are preferentially burned for fuel and provide 4 calories per gram of energy. When fats are ingested, or burned from body stores, they provide 9 calories per gram of fuel. You are effectively doubling your fuel efficiency if you use fat are your primary fuel source from the outset.

By maximizing your capacity to burn fat for fuel, you’ll also be sparing precious muscle glycogen, the carbohydrate stores in your muscle. You have approximately 500g of glycogen stored primarily in your muscles (and some in your liver) that can provide you with 2,000 calories of energy during your race. In contrast, even lean individuals between 7-14% body-fat have 20,000-30,000 calories available for energy use in their fat stores. Wow! That’s a lot of fuel that could be used, if you changed your pre-race food choices.

Skeptical? I don’t blame you, but the preliminary results are impressive.

Dr. Jeff Volek PhD is a world-renowned researcher and author of the FASTER (Fat-Adapated Substrate oxidation in Trained-Elite-Runners) study due to be released later this year. Dr. Volek and his team are investigating the impact of very low-carb diets on an athlete’s capacity to burn fat for fuel, compared to the traditional high-carb diets used by endurance athletes.

A traditional high carb diet would be broken down to approximately 60% carbs, 15% protein, and 25% fat. A low-carb diet would dramatically increase the fat intake to 70%, provide slightly more protein at 20%, and carbs would only make up 10% of the total daily energetic intake.

The initial data is sending shockwaves through the exercise community. Why?

It has been well established in the scientific literature for years that the maximum amount of body-fat that can be burned per minute is 1.0 grams, while the average athlete burns between 0.45-0.75g per minute. 1

The initial results from Dr Volek’s FASTER study smash this concept, showing the LCD athletes are burning upwards of 1.1-1.8g/minute which is way beyond what was thought physiologically possible. 2 You can see the peak fat oxidation or burning rates in the graph below.

Peak Fat Burning During VO2 Max

Traditionally, it was believed that somewhere between 35-65% of your maximum heart rate you switch from burning fat for fuel to carbohydrates. 3 However, this new research is re-shaping the way we think about fueling endurance athletes. The graph below highlights the body’s capacity to burn fat on a low-carb diet at much higher training intensities than thought possible. 2

Fat Oxidation Versus Exercise Intensity

If you ingest primarily carbohydrates your body quickly shifts over to burning the ingested carbs, and your body’s glycogen stores, for fuel. However, if you eat primarily fats and protein before exercise you’ll be able to tap into your fat reserves more effectively. This allows you to spare your muscle glycogen for further along in the race, when you really need it!

This new research is in-line with an ancestral or Paleo approach to eating. You don’t need to rely on an endless array of gels, powders, and pills to produce the best possible endurance race times. If you are engaging in endurance sports to lose weight this is critical, as your excess carbohydrate consumption is likely holding you back from achieving a better body and better health.

For example, you could start your day with a coffee and a tablespoon or two of coconut oil or MCT oil. The caffeine helps stimulate lipolysis, the breakdown of body-fat stores to free fatty acids for fuel and the MCTs provide the added instant energy source. Alternatively, you could have eggs with avocado and a serving a stir-fried kale or spinach. This will allow your body to burn fat for fuel more effectively, as well as improving your health.

Not everyone needs to follow a low-carb diet. If you are purely performance-based and striving for new personal bests than you may want to tread lightly. (Check out my previous article on Eating Enough Carbs Optimal Recovery to get your post-exercise carb fix). However, in a sport like endurance training where carbohydrates are king, this compelling new research highlights that we still have a ways to go in understanding how to most effectively fuel the body for endurance performance.

Train your body to burn more fat and watch your performance, as well as your health, reap the benefits!



1. Venables et.al.; “Determinants of fat oxidation during exercise in healthy men and women: a cross-sectional study”. J Appl Physiol (1985) 2005 Jan;98(1):160-7.

2. Defty, President VESPA, Peter. “The Emerging Science on Fat Adaptation | Ultrarunning Magazine.” Ultrarunning Magazine The Emerging Science on Fat Adaptation Comments. Ultrarunning Magazine, 16 Dec. 2014. Web. 1 May 2015.

3. Lima-Silva A et al. Relationship between training status and maximal fat oxidation rate. J Sports Sci Med. 2010 Mar 1:9(1):31-5

4. Noakes, T., J.S. Volek, and S.D. Phinney. Low-carbohydrate diets for athletes: what evidence? British Journal of Sports Medicine. 48(14):1077-8, 2014.

Interval Training: Stop with the Tabatas and Do Some Gibalas! | The Paleo Diet

Sprinting would obviously have been a necessary requirement for Paleolithic hunter-gatherers, both for the procurement of food and to avoid becoming food! Those who want to argue against that statement with the “persistence hunting” position, I will address that in a future post. Regardless, let’s fast forward to modern day and address a topic pertinent to my initial statement. To say that “Tabatas” have become an extremely popular interval training protocol in the fitness industry would be an understatement. When I wrote a position paper1 back in 2008 on the benefits of sprint interval training, the research conducted by Izumi Tabata et al. was obviously referenced as it added to the body of evidence that supports the benefits of high-intensity intermittent (interval) training (HIIT). However, the interpretation of this protocol in the fitness industry has often been misunderstood, and even when done correctly, I would argue that, for most individuals, it is not the most effective approach to interval training. After all, the protocol tested was simply one that was first introduced by a head coach of the Japanese National Speed Skating Team, Kouichi Irisawa; a protocol one would assume worked well for certain athletes based upon the duration of their events. Further, most good coaches use training methods that are often experimentations that change with time, as more successful protocols take shape. Along these same lines, I believe most people could improve their investment of time by not using the Tabata protocol for their interval training; but rather, use a different approach.

For the uninformed, in 1996, Tabata et al. published the findings of a study comparing moderate-intensity endurance training (MIET – 70% VO2 max for 60 minutes, 5 days per week) with HIIT (170% VO2 max for 20 seconds x 7-8 with 10 seconds recovery, 5 days per week) on a cycle ergometer.2 The study found that HIIT improved maximal oxygen uptake slightly more than MIET; but, also improved the anaerobic capacity by 28% while the MIET had no effect on the anaerobic capacity. So, essentially, a “two for one” in terms of improving metabolic capacities for the HIIT protocol.

While the results of the study were important for the comparison of MIET to HIIT, other interval training protocols have demonstrated similar and; in some cases, even greater benefits with a decreased investment of time.3, 4, 5, 6 These latter studies support what I have witnessed clinically over nearly 20 years, which is, that intensity, not duration, is the key ingredient for beneficial physiological change. The intensity of the HIIT protocol examined in the Tabata study was 170% VO2 max, which, while correctly being labeled supramaximal (above 100% VO2 max) and certainly “high-intensity,” is nowhere near a maximal sprint effort given that humans are capable of intensities around 250%. The power output sustained for a maximal effort for the duration of the exercise time of the Tabata HIIT protocol (140 seconds to 160 seconds), is very different to the power output sustained for a maximal effort for an “all-out” sprint lasting, say, 30 seconds. If 170% VO2 max was all one had to escape a predator in primitive times (or today for that matter), it is pretty much a guarantee that you are going to be out of the gene pool in short order! 100% VO2 max represents the power output attained when one reaches maximal oxygen consumption during a graded exercise stress test. Any human starting out at that equivalent intensity would not find it anywhere near a maximal effort for a short “all-out” sprint.

When sprinting “all-out,” most individuals are going to start slowing down within seconds; but, could probably still hold a decent percentage of their maximum power output for anywhere between 20-60 seconds, depending on their level of conditioning, and, in particular, their ability to handle the lactic acid production associated with supramaximal exercise. Considering the short duration of supramaximal activity, it generates a relatively large volume of excess post-exercise oxygen consumption (EPOC), partly due to the lactic acid production. Research has shown a significantly larger EPOC is generated for a 45 second “all-out” sprint compared to a 30 second “all-out” sprint, and a significantly larger EPOC is generated for a 60 second “all-out” sprint compared to a 45 second “all-out” sprint.7 However, a 90-second “all-out” sprint did not generate a larger EPOC than a 60 second “all-out” sprint. The reason for this is that lactic acid production typically reaches its peak at around 60 seconds of supramaximal exercise, which, in turn, inhibits muscular contraction and thereby decreases the production of further large quantities of lactic acid.  Anyone can easily experience this for him or herself. There simply is not a human on the planet that can maintain close to maximal power output without a precipitous drop-off at around 60 seconds. If you find otherwise, immediately contact your country’s Olympic Committee as I can assure you that you will be in high demand! So, 60 seconds is essentially a maximal and optimal duration to engage in supramaximal activity. Perhaps selective pressure with respect to our ancestral survival played a part in this physiological reality.

Now, back to the Tabata protocol. There are two ways in which individuals in the fitness community are misinterpreting this methodology. First, and perhaps somewhat ridiculously, are those individuals and classes that label their work-outs as “Tabatas” because they simply exercise for 20 seconds (at relatively low intensities), rest for 10 seconds, and then repeat the same for seven to eight intervals, and then, in some cases, even repeat again for an hour long workout. Anyone engaging in this approach is as far away from supramaximal interval training as one can get. The second misinterpretation comes from those that are completing the seven to eight 20 second intervals as “all-out” efforts.  With this approach, based upon the previous discussion about 60 seconds being a maximal duration for “all-out” exercise, any intervals past the first three 20 second sprints are essentially a waste of time. The only way someone can complete seven to eight 20-second intervals with only a 10-second recovery is to back down from an “all-out” sprint, to an intensity similar to that tested in the Tabata study. Doing this certainly has its merits for athletic endeavors that last for 140 seconds to 160 seconds; however, for the average individual and most athletes, I would argue that the protocol researched by the group headed by Martin Gibala from the Department of Kinesiology at McMaster University in Hamilton, Ontario, Canada, is a much more effective approach to interval training.

This protocol, as first described by Burgomaster et al.,3 involves completing “all-out” 30-second sprints (also on a cycle ergometer) with a 4 minute recovery between exercise bouts. The number of sprints increased from 4 during the first two sessions, to 5 in the third and fourth sessions, and 6 in the last two sessions. The total time commitment was 17–26 minutes per session, involving only 2–3 minutes of sprint exercise. Exercise sessions were completed every two to three days such that 16 minutes of exercise was completed in a two-week time period.  The results of this protocol showed a doubling of the participants’ endurance capacity! So these benefits occurred over a two-week period using just 16 minutes of sprinting. Further studies using this same protocol have been shown to substantially improve insulin action in young sedentary subjects, a much-needed outcome in this world full of metabolic syndrome.4 This demonstrates that quality not quantity causes physiological change for the better and, in many cases, the Tabata protocol in the fitness industry has become a methodology that has moved away from quality toward quantity. Further research has now shown that intense bouts as short as 6-20 seconds can have a tremendous benefit on physiological health, emphasizing, again, that intensity, not duration, is the key element to beneficial change.5,6 I have also found clinically, that these very short bouts of intense activity are better adhered to while still providing tremendous improvements in health and performance.

Moreover, I found a common objection to this methodology is that unfit and elderly individuals should not engage in this type of supramaximal activity due to the inherent dangers of engaging in such intense activity. With extensive experience in this field, I have never had a situation where an unfit individual or an elderly individual has had a problem with engaging in this kind of supramaximal activity. In fact, I would argue that it is beneficial to engage in this type of exercise in a controlled environment; rather than leave it to the reality of life where external pressures may demand an effort above which one is physiologically not trained to handle.  Interestingly, an increased QT dispersion (QTd) – a marker of myocardial electrical instability that predicts ventricular arrhythmias and sudden cardiac death – has been shown to be decreased with short-term supramaximal exercise.8 This supports the notion that short-term supramaximal exercise is an appropriate approach for anyone to improving one’s physiological health.

In closing, unless you have an athletic event lasting between 140 seconds to 160 seconds, skip the Tabatas and engage in Gibalas or some other shorter interval training protocol that produces better results with a smaller investment of time.  And don’t overdo the quantity of “all-out” sprints – eight to twelve minutes per week is sufficient to reap the benefits without the risks associated with overtraining.

Dr. Mark J. Smith

Dr. Mark J. Smith | The Paleo DietDr. Mark J. Smith graduated from Loughborough University of Technology, England, with a Bachelor of Science in PE & Sports Science and then obtained his teaching certificate in PE & Mathematics. As a top-level rugby player, he then moved to the United States and played for the Boston Rugby Club while searching the American college system for an opportunity to commence his Master’s degree. That search led him to Colorado State University where Dr. Smith completed his Masters degree in Exercise and Sport Science, with a specialization in Exercise Physiology. He continued his studies in the Department of Physiology, where he obtained his Doctorate. His research focused on the prevention of atherosclerosis (the build up of plaque in arteries that leads to cardiovascular disease); in particular, using low-dose aspirin and antioxidant supplementation. Read more…


1. Smith MJ. Sprint Interval Training – “It’s a HIIT! A research paper discussing the superior health and performance benefits of high-intensity intermittent exercise over low-to moderate-intensity continuous exercise. 2008 //docsmith.org/SIT-HIITbyMJS-1411.pdf

2. Tabata I, Nishimura K, Kouzaki M, Hirai Y, Ogita F, Miyachi M, Yamamoto K. Effects of moderate-intensity endurance and high-intensity intermittent training on anaerobic capacity and VO2max. Med Sci Sports Exerc. 1996 Oct; 28(10): 1327-30

3. Burgomaster KA, Hughes SC, Heigenhauser GJ, Bradwell SN and Gibala MJ. Six sessions of sprint interval training increases muscle oxidative potential and cycle endurance capacity in humans. Journal of Applied Physiology 2005 98:1985-1990

4. Babraj JA, Vollaard NB, Keast C, Guppy FM, Cottrell G, Timmons JA. Extremely short duration high intensity interval training substantially improves insulin action in young healthy males. BMC Endocrine Disorders 2009 Jan 28; 9: 3.

5. Adamson S, Lorimer R, Cobley JN, Lloyd R, Babraj J. High Intensity Training Improves Health and Physical Function in Middle Aged Adults. Biology 2014 3: 333-344.

6. Metcalfe RS, Babraj JA, Fawkner SG, Vollaard NB. Towards the minimal amount of exercise for improving metabolic health: beneficial effects of reduced-exertion high-intensity interval training. Eur J Appl Physiol.2012 Jul; 112(7):2767-75.

7. Withers RT, Van der Ploeg G, Finn JP. Oxygen deficits incurred during 45, 60, 75 and 90‐s maximal cycling on an air‐braked ergometer. Eur. J. Appl. Physiol. 1993; 67(2): 185‐91.

8. Drigny J , Gremeaux V, Guiraud T, Gayda M, Juneau M, Nigam A. Long-term high-intensity interval training associated with lifestyle modifications improves QT dispersion parameters in metabolic syndrome patients. Ann Phys Rehabil Med. 2013 Jul; 56(5):356-70.


I ran the ACU (Association of Canadian Ultramarathoners) 100Km National Championship. I lead the race the entire time, finished in 08:47:18 hours,and won by 23 minutes! I ran this race with a total of 850 calories of a fat/carb/protein blend, finishing the race as strong as starting it.

Endurance Athlete | Adam Takacs

Adam Takacs, 1st Place ACU 100Km Championship

In the past, I would need about 1400-1600cal of sugar to keep going strong and most likely fading towards the end, similar to many other endurance athletes.

As an endurance athlete, the adoption of eating/living a Paleo lifestyle made complete sense to me after some research. After some trial-and-error with my macros, I opted for a higher fat content- lots of bacon!- for more sustained energy. Injuries seem to have vanished, mid-day energy lows are gone, I never feel hungry, and after a win at the Pick your Poison 50KM run and a win at the National 100Km Championship in Niagara, I have no doubts I’ve found my secret weapon.

Adam Takacs

CrossFit | The Paleo Diet

Dr. Cordain,

My name is Carl. I’m an assistant gymnastics coach just down the street at the University of Denver. For personal health reasons, I tried a grain, sugar and dairy free diet a few years ago and was stunned by the results. Since that time I’ve waffled a bit but (mostly 85:15), for the most part, gone Paleo.

Recently, I’ve read Taubes, Sisson and your book, The Paleo Diet for Athletes. I’m preparing to mount an offensive against the conventional wisdom and challenge what we currently tell our athletes in an effort to bring them more towards the Paleo side. I feel a low GI diet will enhance performance and help our athletes keep their body comps to a healthy minimum, something of great importance in a sport which uses such high intensity, ballistic movements and demands aesthetic appeal.

With your books emphasis on endurance sports, I’m wondering about the applicability to a sport like gymnastics. I’d be very interested in hearing your thoughts and, perhaps, a list of resources of relevant research. I just recently came across an article about ketogenic diet and performance in Italian gymnasts which demonstrated no detriment to performance in the short term.

I look forward to hearing from you at your earliest convenience.

Highest regards,


Dr. Cordain’s Response:

Hi Carl,

Joe Friel and I considered doing a chapter on Paleo for strength athletes, but didn’t do so because the dietary principles were virtually identical to those we suggest for endurance athletes.  To date, I am unaware of any scientific or clinical trials of contemporary Paleo Diets involving any type of athletes that have been published in the scientific literature.

Many of the activities and exercises done in CrossFit gyms all over the U.S. and the world tend to be strength oriented.  Further, many  elite CrossFit athletes who compete yearly  at the national CrossFit games (sponsored by Reebok) are avid Paleo Dieters and attribute part of their successful performance to their diet.  I welcome input from CrossFit athletes to comment on their experience.


Loren Cordain, Ph.D., Professor Professor

Sample Menu for Endurance Athlete | The Paleo Diet

Nell Stephenson, Fitness & Nutritional Professional, Ironman Triathlete, and contributor to our newsletter was recently contacted by Details magazine to write up sample menus for endurance athletes: one for a workout day, the other for an off-day from training.

You will find other paleo-friendly menu ideas on Nell’s blog.

Endurance Athlete Sample Menu for Two-a-Day Workout

5:30 AM
Pre-workout Breakfast Smoothie- 8oz brewed, chilled, natural decaf green tea with a banana, egg white protein powder, almond butter whizzed in the blender with some baked yam on the side.

6:30 AM
3-hour bike ride on the trainer-carbohydrate gel taken every 25 minutes.

9:30 AM
Immediate Post-workout recovery drink- HOME BREW (recipe in The Paleo Diet for Athletes) – cantaloupe, egg white protein powder and glucose. Drink plenty of water- keep hydrating.

10:00 AM
Raisins (to restore body alkalinity, continue to help the body recover post workout, and prepare for the session later in the day).

11:30 or 12:00 PM
Grilled Chicken breast, flash-sautéed asparagus, drizzled with flax seed oil and an apple

3:00 PM
Natural unsweetened applesauce with chopped egg whites (to prepare for 2nd workout of the day-shift from the usual Paleolithic macronutrient ratio to the pre-workout focus on carbohydrates).

4:30 PM
Sixty-minute track workout-hard, fast intervals; carbohydrate gel taken immediately post as recovery.

5:45 PM
Banana (high glycemic fruit choice to, again, aid in recovery)

6:30 PM
Poached wild salmon on a bed of steamed kale, mixed green salad, avocado & sliced strawberries, a squeeze of fresh lime juice and a splash of cold-pressed extra virgin oil; sliced oranges on top.

Endurance Athlete Sample Menu for Off-Day from Training

6:00 AM Breakfast
Poached Cod (or Barramundi) on bed of sautéed spinach (with garlic & olive oil), fresh blueberries and strawberries.

9:00 AM
Steamed broccoli, drizzled with cold pressed flax seed oil, sliced orange and chopped egg whites.

Mixed green organic salad, with olive oil and lime wedge, served with grilled chicken, avocado and grapes.

Afternoon Meal
Sliced lean turkey breast used as a wrap, with Mache lettuce, raw almond butter and sliced pear inside.

Kangaroo Kebabs-lean meat, skewered with red onion & yellow bell peppers, marinated over night in olive oil, lemon juice & your favorite herbs, then grilled or broiled. Serve with grilled green onion and a fresh spinach salad with tomato, walnut oil & a lime wedge.

Cinnamon dusted sliced apples-slice an apple, toss in lemon juice to prevent browning/oxidation, then sprinkle cinnamon on top. Enjoy with a cup of herbal or green decaf tea!

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