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In the preface to his book Metabolic Efficiency Training: Teaching the Body to Burn More Fat (2 nd Edition), Bob Seebohar says, “ ask your own questions and become your own experiment.” This sentiment reverberated powerfully with me. I believe we should all take the “ n=1” approach to living.

  1. Be the one subject experiment in your everyday life (whether it be related to training, racing, recovery, nutrition, or your bird watching hobby)
  2. Ask hard and important questions,
  3. Make small, incremental (measureable) changes,
  4. Take notes,
  5. Collect data,
  6. Most importantly consistently REVIEW the data and compare with the corresponding notesin order to go back and make meaningful, informed changes and/or decisions .

Early this winter my coach, Greg Mueller, casually mentioned that he had recently sat down with Ben Stone, a self-professed nutritional and metabolic biochemist (a.k.a. chemical geek - his words, not mine). They were collaborating their respective decades worth of coaching and sports science expertise for the purpose of optimizing the performance of several shared athlete clients. The small tantalizing bit of info that Greg initially shared with me highlighted the percentage of fat consumed in an athlete’s diet (increased to a number I thought was absurd at the time) in order to accomplish certain metabolic changes that would be beneficial for improving performance, especially as an endurance athlete. This was enough to peak my interest, so I looked up this guy, Ben Stone, and did a little reading about his thoughts on fat, “Did Paula Have It Right?”; playing to our (or maybe just my) southern heartstrings, which admittedly sing, when anyone pays tribute to her butter-loving culinary methods.

My next step was to dig up my dusty username and password to MyFitnessPal and start meticulously logging my food intake, at first without trying to change anything (inherently hard because the nature of taking notes and observing/recording things make one self-conscious). This can seem tedious at first. Then it gets scarily addicting, and you find yourself ordering a food scale and eating peanut butter out of a tablespoon for ease of logging (guilty on both accounts). (NOTE: I am not advising you should or shouldn’t start counting calories. Should you choose to do so, I do not advocate using this app for it’s daily calorie recommendations. However, it is fairly intuitive, has an exhaustive library of foods already catalogued and gives a quick break down of daily macronutrient percentages).

Given my continued interest and willingness to makes some changes (a key component), my coach forwarded along a blog about Metabolic Efficiency Testing: Explanation and Motivations. This resulted in three things:

  1. I immediately knew I wanted to get one of these metabolic efficiency tests done soon and
  2. I ordered Bob Seebohar’s book, Metabolic Efficiency Testing (2 nd Edition), and
  3. I found this interview with Tim Noakes on an episode of SportsTalkRadio (the podcast by Glenn Whitney has turned into a wealth of knowledge)

I give you that background story and those resources, to let you know how I have found myself so captivated by the concept and pursuit of metabolic efficiency (a term I am almost ashamed to say I had not heard before I started doing my own reading and research a few short months ago). At 5 weeks into my winter training camp, I was eating a diet roughly based on a 50% fat, 30% carb, 20% protein daily goal, and was a good 5-6 lbs lighter than when I ended my season in October without ever making weight loss a goal in this whole process.

The rest of this article will be an attempt to explain the concept of Metabolic Efficiency (basically a cliff notes version of the first 3 chapters of Bob’s book), and how, should you be interested in being your own experiment and making a change, this concept can potentially improve your performance. I still have a long way to go before I am comfortable talking about and making specific nutrition recommendations to others, so I will leave that to the experts whose writings and research you may discover out of your own curiosity and searching after reading this.

Please take what I have to say as one woman’s n=1, on-going experiment.

In the first chapter of his book, Bob Seebohar introduces three concepts:

Crossover concept – On the graph below, increasing exercise intensity (as indicated by increasing HR) is measured on the bottom axis and the percentage of fat and carbohydrate utilization are measured on the left and right axis respectively. This concept describes the process whereby the amount of energy provided from fat metabolism decreases and the amount of energy provided by carbohydrate metabolism increases as exercise intensity is increased. When tested, it also allows an athlete to find his/her metabolic efficiency point (if this point indeed exists for an athlete, but that’s a topic for a whole other article)   Metabolic Efficiency Point (MEP) –point at which the fat utilization line (blue) intersects with the carbohydrate utilization line (red)

Metabolic Efficiency Chart

Metabolic flexibility At a loss for better words to describe a somewhat nebulous concept, I will just quote Bob Seebohar from his book here, Metabolic flexibility is the capacity to utilize both fat and carbohydrate fuels and transition between them in response to changes in dietary energy intake or circulating substrate concentrations.”

  • This concept pertains to the idea of nutritional periodization, whereby an athlete adjusts his/her carbohydrate intake based on training and racing schedules to optimize performance.

Metabolic efficiency – This concept, finally, is the result of utilizing and optimizing an athlete’s metabolic flexibility (monitoring and periodizing food at appropriate times in training and racing) in order to push his/her crossover or metabolic efficiency point farther to the right along the graph, meaning he/she now has the ability to burn fat for energy at a higher intensity (HR) and preserve those precious, limited glycogen stores.

  • Given how many times in a day we stop and make choices about food, compared with the amount of time we are actually training, Bob makes an incredible point.   The opportunity to make meaningful changes and improvements to metabolic efficiency then comes to about a 75% contribution from nutrition and 25% from exercise. That’s powerful.  

So why all the fuss about fat?

Two important sets of numbers to know here:

  • Most of us carry around 1,300-2000 calories of carbohydrates, often referred to as our glycogen stores.  These stores can support up to 2-3 hours of easy to moderate intensity exercise before needing to be replenished or risking the proverbial “bonk.”
  • The next numbers obviously vary a bit more from person to person, but the average adult can carry around upwards of 60-80,000 calories in fat stores. Even very lean individuals have upwards of 30-50,000 calories stored as fat.

It makes sense then that as endurance athletes we should want to tap into this massive store of energy in the form of fats that we are already carrying around before ever consuming any additional calories from the various and sundry “sports candies” out there. Like the petulant child who is wholly unsatisfied with the “do as I say and not as I do” axiom … We obviously can not just say to our bodies, “Burn primarily fats for fuel, pretty please!” However, through both appropriate training intensity and nutritional choices, we can coax our metabolism into being a lean, mean “fat-burning” machine at baseline.

Train Appropriately Aerobic (25% contribution)

The “aerobic zone” is what most people refer to as Zone 2 or < 65% of maximum intensity. The article in the last X3 newsletter, Getting into the Zone:Benefits of Performance Testing, touched on the importance of testing for, knowing, and training in one’s appropriate zones. Training specifically in this “aerobic zone” at appropriate times in a training program leads to increases in both the size and the number of mitochondria. It also increases certain mitochondrial enzymatic activity. If that starts to make your eyes cross or head spin, just know this … more mitochondria means more ATP, which means more energy production (a good thing). Increased mitochondrial enzymatic activity (via a more complex biochemical pathway than I care to try and explain) favors lipid metabolism (a very good thing … trust me).

Finally, Control your BS (75% contribution)

Consuming a carbohydrate heavy meal is a sure-fire way to spike your blood sugar (BS). When this happens, your body (more specifically your pancreas) secretes insulin to get the wily BS under control.   The resulting high levels of insulin inhibit fat metabolism, drive your cells toward more carbohydrate metabolism, and via other again more complex biochemical pathways, lead to the storage of fat in adipose tissue which is not good. Alternately eating higher proportions of protein, fats, and fiber at every meal dampens the insulin response. Less circulating insulin facilitates a higher degree of fat burning. The take away point here are that controlling your BS allows you to control your insulin response, which promotes lipid metabolism. Basically, control your BS!

One final point to drive home, about why particularly as an endurance athlete, you should consider increasing your metabolic efficiency: As I mentioned earlier, the longer your body is able to tap into it’s existing and extensive lipid stores, the longer you can go before tapping into those precious limited glycogen stores. This means your body is capable of functioning on fewer consumed calories per hour during exercise bouts, which is good for two reasons. First, that’s less food you have to actually pack around on the bike or run. Second, there is less potential for GI distress because you are actually eating less food.

Just some food for thought, or better yet, maybe just a few new thoughts about food (and exercise) from the #BlunckOrbit

Until next time,

X3 Endurance HallieBlunck

 – Halie Blunck, Professional Triathlete and X3 Advisor

 

References:

Metabolic Efficiency Training: Teaching the Body to Burn More Fat (2 nd Edition) © 2014 Bob Seebohar


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