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Training for a Race? Try Fat Loading for Endurance

As a sports nutritionist and longtime endurance runner, I have always been interested in the connection between my diet and performance. Recently, I completed an ambitious goal of completing two marathons in one week and decided to test a 10-day fat-loading period as prep. I based this experiment on emerging research and promising anecdotes from various athletes also experimenting with this approach.

The result?

I ran my strongest marathon times, reaching a personal record in both marathons (yes, I ran faster in the second marathon, only a week apart) and placed within the top 20 for my age group in both races.


What Is Fat Loading?
The premise of fat loading is to consume 60 to 80 percent of your daily calories from fat to help train the body to burn fatty acids for fuel and preserve precious muscle glycogen. This is ideally used for endurance events lasting longer than two hours, since research hasn't shown an impact for shorter-duration races.

You start two weeks out from the race, using 10 days for fat loading, followed by a three-day carbohydrate-replenishment period in the final days before the race, switching to 60 to 80 percent of calories from carbs, not fat.

The Science Behind Fat Loading
Research has shown endurance-trained cyclists who ate a high-fat diet (more than 65 percent of calories from fat), compared to those who maintained their "habitual" eating patterns, improved their time trial performances. Both groups consumed a high-carbohydrate diet (more than 75 percent of calories from carbs) three days before the time trials, meaning the fat load was the meaningful variable.

Additionally, research has shown athletes following a high-fat diet (more than 70 percent daily calories) have a slower rate of carbohydrate utilization (prolonging their energy) and took longer to become exhausted.

Benefits of Fat Loading
The biggest benefit is the ability to run, cycle or swim longer without bonking -- or hitting the wall. It's also easier to maintain your energy levels and stamina through the duration of your race.

Cons to Fat Loading
While you're typically tapering during the final two weeks leading up to your race, you're still training, so these last few workouts will be carbohydrate-depleted. I found my energy levels and stamina were much lower, as was my motivation to run; it may cause your confidence to drop and allow doubt to creep in.

You may also find you experience a version of detox in the first couple of days of fat loading (I did). I attribute this to a dramatic reduction in sugar intake. Be sure to drink lots of fluids, rest up and be good to your body with Epsom salt baths or massages if you can.

What to Eat While Fat Loading
* Trail mix made with only nuts and seeds (and coconut flakes and cacao nibs)
* Chia seed pudding sweetened with stevia and vanilla extract
* Avocado
* Leafy green salad with oil- or nut-based dressings
* Whole olives
* Olive tapenade
* Sauteed greens like chard, asparagus or broccoli in coconut oil and spices
* Blended smoothies made with nut butter, protein powder, nondairy milk and ice
* Unsweetened almond or coconut yogurt with nuts and seeds instead of granola
* Raw chocolate truffles or 80 percent or higher dark chocolate
* Nut butter
* Coconut chips
* Coconut oil

One Day Fat-Loading Meal Plan
Breakfast: Bonkproof Coffee (coffee, nondairy milk, coconut oil and Vega Sport Performance Protein blended and served hot), followed by a workout.

Snack 1: Recovery Cookies-and-Cream Smoothie Bowl with Vega Sport Performance Protein Vanilla. Blend with one tablespoon of cashew butter, two tablespoons of cacao nibs, one cup of ice and one cup of unsweetened almond milk (blend until smooth and thick enough to pour into a bowl). Layer with nuts and seeds for crunch and texture.

Lunch: Diced tofu or tempeh scramble with shredded chard or kale and olives (use coconut oil liberally in the frying pan).

Snack 2: Whole avocado sprinkled with sea salt, pepper and balsamic vinegar, or just simply dive in with a spoon.

Dinner: Leafy salad with walnut "meat" (grind walnuts in the food processor with spices and celery for added texture).

Snack 3: Unsweetened almond yogurt parfait layered with chia seeds, almonds, cacao nibs and two sliced strawberries.

You can use a calorie tracker to make sure your ratio of proteins to carbohydrates to fats is balanced.

Would I Do It Again?
As a foodie, it was a more monotonous diet than I would prefer to maintain on an ongoing basis. However, the promising results have inspired me to try it again in future races. It's only for 10 days, and the memories of a personal-best race last a lifetime.

I encourage other athletes to test it out if they are in search of a next-level performance advantage, especially experimenting with a plant-strong version of the diet.


Readers -- Have you heard of fat loading for an endurance race? Have you tried it before? What was your experience? How do you prep for a race? Leave a comment below and let us know.

Emma Andrews is a registered holistic nutritionist, certified in plant-based cooking and National Educator at Vega. Based in Vancouver, British Columbia, Emma is an endurance runner and cross-training addict who believes the kitchen is your playground. She loves exploring new and innovative ingredients, recipes and food trends almost as much as she loves beating a personal best in trail and road races all around North America.

Learn more about Emma’s work and connect with her on Twitter, Instagram and Pinterest.


Yeo WK et al. (2011) Fat adaptation in well-trained athletes: effects on cell metabolism. Journal of Applied Physiology, Nutrition and Metabolism; 36(1):12-22 Accessed 7/1/15 from

Lambert EV et al. (2001). High-fat diet versus habitual diet prior to carbohydrate loading: effects of exercise metabolism and cycling performance. International Journal of Sport Nutrition and Exercise Metabolism;11(2):209-25.

Lambert EV et all. (1994). Enhanced endurance in trained cyclists during moderate intensity exercise following 2 week adaptation to a high fat diet. European Journal of Applied Physiology and Occupational Physiology; 69(4):287-93


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