Carbs, Fats, and Aerobic Training

When you first dive into Primal Endurance, you quickly realize that Mark and Brad REQUIRE that you start your race season with an 8-12 week aerobic base building period.  What does this mean and why do this?  First lets start off with the why?

The traditional thought behind training for an endurance event revolves around three main components.  First is logging the right amount of miles.  The thought being the more miles you log the better prepared you are going to be for your endurance event.  In order to have the energy needed to log these huge numbers of miles each week you need to fuel your body.  This brings us to the second component, how you fuel your body.  Again, traditionally this means eating a large number of carbs.  Everything from sugary drinks, cereals, pastas, breads, gels, energy bars, etc.  Just Google how to fuel your body for an endurance event you will likely find a number of suggestions on how to shove as many carbs in your body as possible.  Finally we need some advice as to what workouts to do, and how many miles to run, so we traditionally turn to a training plan to guide us on our journey to finishing our endurance event.

So what is the problem with this approach?  There are a number detailed in the book, but here are the ones that suck out to me.

Lets start out with the typical endurance athletes diet, because everything builds from what you put in your body.

Fueling your body with carbs causes your body to store excess body fat.  When you eat carbs the body transforms them into glucose, but since your body doesn’t need the glucose after you are done with your workout your body stores the glucose as fat for later.  The problem with this is that your body wants to fuel itself with glucose and not fat so the glucose it stored as fat never gets used.  This is why even though you are training hard you may still be carrying around extra fat on your body.  Mark and Brad provide some pretty amazing facts to back this up.  For example…

First of all, we’re not making this stuff up. Dr. Timothy Noakes, long considered the world’s pre-eminent endurance exercise physiologist and whom you’ll read about frequently in this book, cites a study showing that a full 30 percent of the participants in the Cape Town Marathon were classified as overweight or obese. That’s the same overweight/ obese percentage as the world’s population as whole, as reported in the 2013 Global Burden of Disease Study.

Sisson, Mark; Kearns, Brad (2016-01-04). Primal Endurance: Escape chronic cardio and carbohydrate dependency and become a fat burning beast! (Kindle Locations 429-432). Primal Nutrition, Inc.. Kindle Edition.

In addition, burning carbs is kind of like burning coal.  Burning coal for energy produces a ton of pollutants.  When your body burns carbs it releases free radicals into the body, kind of like the pollutants released when burning coal.  These free radicals wreak havoc on the body causing oxidative damage and accelerating aging.

The final problem with fueling with carbs is that your body has a very limited supply of glucose available for use at any given time.

We are only able to store four to five hundred grams, or sixteen hundred to two thousand calories (highly trained athletes can teach their bodies to store a bit more than the average person) of glycogen in our liver and muscle tissue, and there’s only around five grams of glucose in our bloodstream at any given time.

Sisson, Mark; Kearns, Brad (2016-01-04). Primal Endurance: Escape chronic cardio and carbohydrate dependency and become a fat burning beast! (Kindle Locations 2496-2498). Primal Nutrition, Inc.. Kindle Edition.

Once you run out of glucose to burn, you bonk.  This is why endurance athletes that fuel their body with carbs need to refuel with carbs during a race, they essentially run out of fuel if they don’t.

What are the solutions to these problems?  In the book Mark and Brad propose the solution is to fuel your body with fat.  This involves changing a couple of things.  First you need the fat to burn.  However we don’t want to get that fat from carbs because we don’t want to provide the body with the carbs to burn.  Instead we just want to eat more healthy fats while at the same time limiting the carbs we take in.  Mark and Brad suggest you take in anywhere from 50-150 grams of carbs a day.  If you want to have optimal fat loss you should try to stay below 100 grams of carbs a day.  In addition the carbs you take in should be high quality carbs.  Things like fruits, starchy vegetables like sweet potatoes, and quinoa are all good sources of high quality carbs.


The rest of your diet should be composed of meat, fish, foul, eggs, and non-starchy vegetables.  So in summary you want to decrease your carb intake, while at the same time increasing your healthy fat intake.  Everything else should be vegetables, meat, fish, foul, and eggs.food_pyramid_flat_2011sm-1

Next we need to train the body to burn fat instead of glucose.  To do this we need to change the way we are training so we are training at a level where the body prefers fat as fuel over glucose.  This level is different for everyone and it seems to depend on your age.  Luckily there is a formula you can use to give you your fat burning heart rate zone.  That formula was designed by Dr. Phil Mafetone and is extremely easy.  Simply subtract your age from 180 and that is the point at which your body will switch from burning primarily fat to burning glucose.  For example, I am 31 years old so my max heat rate would be 149.  If you stay at or below this heart rate during your training your body will burn more fat than glucose.  By keeping our training at this level we can reprogram our bodies to burn more fat than carbs.  This type of training is called aerobic training.

To most endurance athletes training at or below this heart rate will feel incredibly slow and hard to do, as in hard to stay below.  Mark and Brad stress that you MUST stay below this aerobic threshold or else your body will continue to prefer glucose over fat.

So how long does it take to train your body to prefer fat over glucose?  Mark and Brad suggest you take 8-12 weeks to train at or below your aerobic threshold.  During these 8-12 weeks you should NOT DO ANY anaerobic training.  This includes training above your aerobic heart rate, and any kind of strenuous strength training.

If you do your 8-12 weeks of aerobic training AND switch your diet to include more fat and less carbs your body will begin to prefer to burn fat over glucose and will no longer require you to consume as many carbs as before.  This will help you loose fat and have a more ideal body composition, reduce the release of free radicals into your body, and allow you to race longer without the need to refuel during the race.

You may think that training at this low heart rate and slow pace will somehow hinder your endurance goals.  It is actually the opposite.  By training at this level you will become more aerobically efficient.  This will allow you to continue to become faster even though your heart rate remains the same.  How will this help you during your endurance event?

When you are performing in an endurance event, which heart rate system do you think you use the most, anaerobic or aerobic?  The answer is aerobic, you would not be able to finish such long endurance events if you were using your anaerobic system.  So if you are becoming more aerobically efficient and you are primarily using your aerobic system durning a race than you are going to become faster overall during the race!

This all sounds good, but how does it apply if you are an obstacle course racer?  We will take a look at that in the next blog post!


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s