Is Fat the Best Energy for Endurance Sports?

Melanie Ramos 10 min. of reading Fats Leave a comment

Today in this article we analyze Fat and Endurance Sports, is it better than consuming carbohydrates?

Glucose has always been used as an energy source for athletes; in fact, it’s the ideal fuel for intense efforts, but the glycogen “store” is very limited, whereas the “store” for fat is huge, so could fat be the best energy for endurance athletes?

High-Fat Diet

If we stick to the previous premise and manage to get our body used to using fat as the main fuel, any of us, no matter how skinny, will have enough energy to finish a marathon without problems (mind you, I’m talking about having energy, being adapted to run that distance is another story).

But the idea doesn’t stop there, if we have more fat and use it more, we’ll have more intact glycogen reserves for when it’s needed since the body would be used to burning fat most of the time and only in “emergencies” would we need that extra energy (from glycogen).

There’s also an evolutionary perspective on focusing on eating more fat, which is that it’s assumed humans have been used to high-protein and high-fat diets for millions of years, so our bodies should be better adapted to digest and use this kind of energy.

Extreme fatigue states are linked to very low glycogen reserves, so if we were “pro-fat burners” we wouldn’t reach those states

To sum up the premise we want to explore, it’s whether an athlete who eats more fat and knows how to use it as fuel will have bigger fuel stores to draw from, and therefore, is less likely to hit a bonk, unlike someone whose main fuel is carbohydrates

Was the Paleo Diet High in Fat?

It’s clear that in the Paleolithic era, humans were hunter-gatherers, but that doesn’t mean they only ate meat and fat. On one hand, if we focus on the wild animals they ate, these had much leaner meat than today’s animals, meaning they didn’t have as much fat as modern ones. Alimentos Prohibidos Dieta Paleo

On the other hand, wild plant foods contained less fat, more protein, more fiber, and more nutrients. In fact, it’s most likely that the Paleolithic diet (1) was around 22% of calories from fat (5% of that fat being saturated fat).

To keep reading about this topic, you can click on Paleo Diet: What It Is, Health Benefits, What You Can Eat, Is It for Athletes?...

Is Fat a Better Fuel for Endurance?

There’s a study (2) that analyzed five elite endurance cyclists over a week where they were given a carbohydrate diet (60% carbs, 30% fat, and 10% protein) and then switched to a ketogenic diet (85% fat, 13% protein, 2% carbs), with the same calorie amount, for 4 weeks.

The test was to monitor endurance capacity by cycling at 62 to 64% intensity VO2 MAX, where results were 151 minutes on the high-fat diet versus 147 minutes on the high-carb diet, not very significant…

The only important difference was that much more fat (double) and much less carbohydrate was metabolized during exercise on the high-fat diet. In other words, high-fat diets preserve more carbohydrates, which is good, but at the same time store less carbohydrate, which can be bad.

The study focused on low-intensity training, where it was seen that you can perform equally well on a high-fat or high-carb diet, but if tests had been done above 85% VO2 max, the athletes on the carb-rich diet might have done better

Eating More Fat Helps in Endurance Sports

Many studies link a performance boost in endurance sports with increased fat intake, but these studies have certain quirks like subjects depleting all glycogen before the test or tests done at low intensities…

Same Performance and Better Cholesterol

Looking at well-conducted studies like this one (3) from the University of Otago, where 34 experienced endurance cyclists were split into two groups: one on a high-carb diet (60% carbs, 20% fat, 20% protein), and the other on a high-fat diet (45% fat, 40% carbs, 15% protein), for 12 weeks.

Both groups improved time to exhaustion during effort tests with no change in VO2max during the study period. Therefore, endurance cyclists could choose between high-fat or high-carb diets without any negative impact on their progress.

And in both groups total cholesterol dropped, HDL was maintained, and LDL decreased, meaning high-fat and high-carb diets led to equivalent and positive changes in blood lipid profiles, even though most fat consumed was saturated. This shows fat isn’t harmful to cholesterol.

Studies Supporting Carbohydrates?

We should also consider a study (4) from the University of Copenhagen, where two groups of 10 men were put on a high-carb diet (65% carbs) and a high-fat diet (62% fat) with training 3-4 days a week for 60-75 minutes at 85% VO2max, for 7 weeks.

The result concluded that high-carb diets had better performance than high-fat diets over 7 weeks, since although VO2max increased 11% in both groups after seven weeks, time to exhaustion in effort tests (82% VO2max) was much longer in the high-carb group (102 minutes vs. 65% of the high-fat group).

Keep in mind these were untrained people, meaning they had no experience or metabolic adaptation to endurance exercise, so results could be different in experienced athletes metabolically adapted to “fat burning“.

Most studies concluding that high-carb diets outperform high-fat diets for endurance sports are done over short periods, not allowing enough time for metabolic adaptation to primarily using fat as fuel, although some like this one (5) show that normal carb loading didn’t improve half marathon times in experienced runners.

It’s true that Kenyans follow a high-carb, low-fat diet year-round, avoid fatty foods, and moderate protein intake, yet they’re the best in endurance sports. While genetically superior (so you can’t just apply this to everyone), no one has tested giving them a high-fat diet, what if they got even faster?

High-Fat Diet with Carb Loading

A slightly different study (6) tested cyclists with very high-fat or high-carb diets followed by 3 days of carb loading (150 minutes at 70% VO2 max followed by 20 km all-out), concluding that the high-fat diet (with carb loading) improved the 20 km time by 4.5% (from 30.9 minutes to 29.5 minutes) compared to the high-carb diet (also with loading).

The reason was that the previous diet was linked to less glycogen use during the 150 minutes before the 20 km sprint, leaving more glycogen available for that test. In other words, the high-fat diet helped muscles use less glycogen and more fat, and also helped store more glycogen during the 3-day carb loading.

Adapting to Fat as Fuel

If you want fat to be the Best Energy for Endurance Sports

With everything we’ve seen so far, it’s reasonable to think that for very long endurance stages, a few weeks on a high-fat diet with a 3-5 day carb loading before competition can be a much better nutritional prep than just a high-carb diet.

For more info click below on How to Do Carb Loading?

This is because when you eat a high amount of fat for a while, the body gets better at oxidizing it and using it as energy, so during the race this energy (fat) is mainly used, and the “store” for this energy type is much bigger than glycogen’s.

Also, that 3-5 day loading supercompensates muscle glycogen levels, so when higher intensity is needed during the race, you can tap into those stores without any problem. Full glycogen levels and less time needing that energy become the perfect ally for long stages where relying only on glycogen would lead to complete depletion and dreaded extreme fatigue (the wall, the bonk, hitting the wall…).

There’s only one problem: you have to adapt to using fat as fuel, so it’s recommended to gradually increase fat intake over several months before the long endurance event, because if done too quickly, performance will most likely be the opposite of what you want.

Conclusion

Fat is very abundant in the body, so trying to use it as a nearly unlimited energy source would be a very smart strategy, although for very high intensities it seems we need carbs, but it looks like the body can adapt to handle high intensities with more fat use, though more studies are needed.

The key for endurance isto keep enough glycogen in muscles and stores, and what’s scientifically proven is that this is achieved with high-fat diets for weeks and specific carb loading, so more fat is used at moderate intensity, more glycogen is stored, and more is available when needed.

Original source |Web Peak Performance