Fat Loading: Does it work?

*I apologize in advance for all the drool worthy fatty food pics*

I can’t say this enough, our bodies are AMAZING. Why? Simply because we are capable of adapting to our immediate environment in so many ways!

As you can see from my previous posts, we are highly adaptable creatures. Train hard enough and you are able to run that much faster because your body has made the necessary changes to adapt to it.

In this context, going on a high fat diet (and low carb) would force your body to utilise it more efficiently.FullSizeRender_1

I know what you must be thinking: YAY! Another reason to go on a high fat diet! Of course, it is NOT as simple as it looks. If it was, obesity and other metabolic diseases would not exist because we’d all be super fat burners!

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Previously, we explored how endurance training can help us become efficient fat burners.

Let’s take a look at Fat Loading:

A few studies have found that in general, fat loading does improve performance during endurance based activities [1 , 2]. During an endurance event, intramuscular triglycerides (muscle fats) contribute a significant amount of the total fats used [3]. Consumption of a high fat diet has been shown to enhance the utilisation and storage of these muscle fats. This is the adaptation seen when undergoing endurance training.

However, note that high fat diets only seem to improve time to exhaustion in moderate intensity activities [4].  This is hardly the case in real world racing where there will be times of acceleration, uphill surges, midway and finishing sprints which are moments of high intensity bouts. Such a diet will not work for shorter higher intensity races (5K or 10K race) [5]. Also, a prolonged high fat diet seems to impair endurance performance [1].

The Protocol

Remember that you are not depending on just ONE TYPE OF FUEL at any one time during a race, it is a combination of the different types of fuel. Research has found that it was better to have the best of both worlds – a hybrid diet. A typical fat loading protocol would include a few weeks (1-1.5 weeks) of high fat diet to stimulate the fat oxidation capacity followed by a period (2-3 days) of high carbohydrate diet preceding a race to top off glycogen stores [6].

If you start off with low glycogen levels, performance will indeed be impaired!IMG_6893

Carbs and fat!

The Downside

There’s always a downside. The thing about fat loading is that while it enhances fat metabolism at moderate intensity activities, the use of glucose as a source of fuel is impaired. Studies have found that prolonged fat loading has been associated with a decrease in hexokinase activity (enzyme involved in the first step to using glucose as fuel) and pyruvate dehydrogenase activity (another enzyme involved in using pyruvate as fuel) in trained individuals [7]. This can affect the individual when the demands for muscle carbohydrates are high.Processed with VSCOcam with f2 preset

Personal Thoughts

I’ve gone through a few research papers and they all seem to have very different results/conclusions due to the heterogeneity of the trials.

Every individual is different. Some people can thrive on a high fat diet whereas the same diet might leave another person sick in the stomach. It is quite hard to screen for people who can adapt well to high fat diets to improve performance.

FullSizeRenderJust when I thought I could EAT ALL I WANT!

I personally don’t think I can go on a high fat diet. I have not tried though! But I guess for anything below the marathon distance, going on a high fat diet does not give any significant benefits.

Energy gels are readily provided throughout a race to help you avoid the dreaded bonk and maintain blood glucose levels.


However, if you are planning to explore ultraendurance events, it may be worth your time to give this protocol a go. *At your own risk!* Experiment with 7 days of high fat diet followed by 2 days of carbo loading before an endurance event, who knows, it just might help!

*Don’t try this before your race though, practice first!*

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At the end of the day, TRAINING is inevitable! It guarantees improved performance and turning you into an efficient FAT BURNER!

Proper training coupled with a wholesome well-balanced diet DURING training is much more important when it comes to improving your performance.

I am curious to know what you think! 🙂

Keep Running!



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