Race Prep: Fat Loading

I ran the Sioux Falls marathon just over a week ago.  I spoke in my last post about some of the training and nutritional changes I made during the weeks I spent preparing for this race.  This post I’m going to dive more into the details of my nutrition during the taper phase of training.  Many endurance runners have experienced hitting the wall: “Sugar, stored in your liver and muscles bound into large chains called glycogen, is the prime fuel for a distance runner. While your body can burn fat directly for energy, it tends to prefer glycogen, as it is easier to burn. Much of the lore about the marathon being “half over at twenty miles” has to do with the fact that this is about as long as the average person’s muscle glycogen stores will last.” 1  Many marathoners say the real race begins at mile 20.

This past year, I’ve experienced that dreaded wall.  I felt it both in Phoenix and again in Lincoln.  Hitting the wall can cause devastating results when you’re going for a PR. This is what gave me the push to change my taper nutrition. I’d heard a little bit about a topic called Fat Loading.  I read about fat loading in the book “The New Rules of Marathon and Half Marathon Nutrition” by Matt Fitzgerald.  Matt suggests “the more fat you include in your diet as a runner, the more fat and less carbohydrate your muscles will burn when you run. This adaptation could increase your endurance and reduce the likelihood of your hitting the wall in long races, such as marathons because the depletion of muscle carbohydrate stores.”  The 13 day plan is split into two parts.  The first being the fat loading phase.  During the fat loading phase, the runner’s diet consists of 65% of total calorie intake coming from healthy fats for 10 days.  Healthy fats coming from foods such as avocados, nuts, olives, coconut oil, eggs, and fatty fish such as salmon. Following the 10 day fat loading phase, it transitions to three days of carb loading, plus race morning.  Carb loading consists of 70% of calories coming from carbs.

Thirteen days before the Sioux Falls marathon I started my fat loading plan.  The menu was pretty monotonous and offered little variety.  Also, the first five days of fat loading were pretty difficult.  I found myself exhausted and lacking my normal energy.  Luckily, it works out that most runs in this time are not key workouts.  It was around the sixth day I felt my body starting to adapt to the dietary changes.  I started sleeping better, my energy was returning to normal, and my mood improved.  I was curious as to how this change in my diet would affect my weight and body fat percentage. Surprisingly, I leaned out.  I was eating about 200 calories more per day, but lost 2 pounds and dropped additional body fat.  Don’t fear the fats!  I will admit that at the end of the 10 day fat loading, I was more than ready to have a huge bowl of oatmeal!

During the ten days of fat loading I thought I’d have no problem getting my carbs in once I hit that phase.  Boy was I wrong!  I was eating oatmeal, sweet potatoes, rice cakes, bananas, grapes and whole wheat spaghetti, but day one I fell short of my carb intake goal of 400-590 grams per day.  It was at this point that I realized in the past when I thought I was carb loading, I was falling quite short of what my body really needed for race day.  I spent some more time researching foods that would provide me the highest carb percentage and still support my diet goals.  By day three I had my carb intake up to 450 grams!  And race morning I nailed my nutritional plan to a tee.  Pre-race breakfast was 72 grams of carbs, and my goal was 65.

Knowing I hit the numbers allowed me to step into the start corral of the race feeling confident that I had prepared well and my body would support me though the miles.

Have you ever tried fat loading before a race? If so, what did you think of it?  How did it go?

2 thoughts on “Race Prep: Fat Loading

  1. I’ve never ‘fat loaded’ before, but I’m fascinated. I’m going to get my hands on that book and maybe give it a whirl for Chicago. I’m generally at a loss, nutrition-wise anyway, so any guidance is good…

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