Is a High-Fat Diet Healthy for Runners?

Trends come and go in the running world. Often, it’s hard to tell what will stay and what will fall by the wayside.

Not many people are wearing Vibram FiveFingers anymore, but compression socks seem to have cemented themselves as a nearly-essential part of a runner’s wardrobe.

A new debate that’s caught fire recently is the health and performance benefits of a high-fat diet for distance runners.

If you are feeling lost in the wealth of articles that come out about diet and which is the best diet to consume to perform to your potential as a runner, let us find a way through the jungle, and share the results with you.

Today we are going to be focusing on a high-fat diet while limiting carbohydrates?

By the end of this article, you will know whether it is time to kiss goodbye to your pre-race pasta dinner, or keep them going for your body (and mind)!

Is a High-Fat Diet the Future of Distance Running?

Traditionally, exercise physiologists and nutritionists have recommended a fairly high amount of carbohydrates in your diet. The logic is fairly simple: distance runners burn a lot of carbs during training, and research has demonstrated that carbo-loading before a long-distance running event (like a marathon) is beneficial from a performance standpoint.¹

Recently, however, another narrative has emerged.

In a 2014 editorial, physiologists Timothy Noakes, Jeff Volek, and Stephen Phinney argue that high-carbohydrate diets carry health risks, and that, given time, athletes can adapt to diets that are very high in fat and very low in carbohydrates.²

Here’s the deal:

The purported benefits are twofold: first, athletes on a high fat diet could avoid the health problems that might be associated with a high carb diet.

Second, changes in metabolism at the cellular level allow athletes on a high fat diet to burn fat at a much higher rate, which could be a huge advantage in endurance events—a “fat-adapted athlete”, the authors argue, could complete multi-hour training sessions or competitions without needing to ingest any external food sources.

Research behind the high-fat claims

These sound pretty impressive, but how much substance is there to these claims?

Even Noakes, Volek, and Phinney admit that research to date has been inadequate.

In an earlier review article, Asker Jeukendrup of Loughborough University in the UK points out that most studies on the effects of low-carbohydrate diets have been very small and of dubious quality.3

Indeed, even later studies, like a 2012 paper by researchers at the University of Rome that found that a low carb diet had no effect on 30min time-trial performance, still use small sample sizes—only six masters athletes, in this case.⁴

It get’s worse:

Other work by researchers at the University of Connecticut and The Ohio State University looked at the effects of a low carb diet in ultramarathoners. Since previous research has found that low carb diets decrease blood markers of inflammation in obese and sedentary people, the researchers hypothesized that a low carb diet might also decrease the well-known spike in inflammation following long distance running.⁵

A sizable group of twenty male ultramarathoners were selected, half of which habitually consumed traditional high carb diets, and half of which were on a low-carb / high fat diet (11 % of calories from carbs, 71% from fat, and 19% from protein).

After a three-hour treadmill run, blood samples were taken and analyzed for markers of inflammation. While the treadmill run did result in the expected spike in inflammatory markers in the blood, their levels did not differ between the high fat diet and high carb diet groups.

Why are we still considering a high-fat diet good for runners?

Despite this, there is ample evidence that Noakes, Volek, and Phinney are correct on at least one one count—high fat diets do change cellular metabolism.

In his 2003 review article, Asker Jeukendrup cites numerous studies demonstrating that your body responds to a high fat, low carb diet by increasing its ability to mobilize and burn fat for energy during exercise.³

Unfortunately, Jeukendrup also points out that the contributions of fat to your energetic needs are negligible once you start running fast.

What constitutes “fast”?

Jeukendrup writes that, above 75% of your VO₂ max, your body burns very little fat. For reference, marathon race pace is between 75 and 85% of VO₂ max.

What does that mean?

So, a high fat diet might help stave off a need for refueling during long training runs and during ultramarathon races, but it won’t stop you from “hitting the wall” in a marathon race.

Jeukendrup notes that the long-term health effects of a high-fat diet in athletes are unknown, though Noakes, Volek, and Phinney would surely point out that the health risks of high carb diets in athletes are not known either.

What’s the bottom line?

As usual, we’ll have to wait patiently for the large, methodical studies that will eventually put these arguments to rest.

Until then, the only people who would appear to benefit from a high-fat, low-carbohydrate diet are ultramarathoners and Ironman triathletes, whose training sessions and competitions are long enough where burning more fat and less carbohydrates at moderate exercise intensities would offer a distinct competitive advantage.

I am an Ultra-marathoner, What are the Best High-Fat Foods for me?

If you are covering those longer distances where you are running at a low enough intensity level for your body to burn fat for fuel, we are going to share the best foods you can add to your diet.

This does not mean you can go out and binge on fried chicken with hopes of burning it all off in your next ultra. Not all fats are created equal, and here are 20 foods that you could add to your diet without serious side effects (if consumed in moderation!):

• Almonds
• Walnuts
• Pecans
• Macadamia Nuts
• Cashews
• Pistachios
• Avocados
• Black Olives
• Dark Chocolate
• Chia Seeds
• Flax Seeds
• Pumpkin Seeds
• Sunflower Seeds
• Olive Oil
• Coconut Oil
• Butter (try to keep it grass-fed- did you listen to our podcast with Dr Gangemi?)
• Chickpeas
• Whole Eggs
• Full Fat Yogurt
• Parmesan Cheese
• Cream Cheese
• Beef (Grass-Fed if possible)
• Salmon
• Trout
• Mackerel
• Sardines
• Herring

Make sure you speak to a doctor before making any major changes to your diet, but if you do try cutting those carbs in favor of a high-fat diet, let us know how you get on in the comments. Your feedback may be what other runners need to make a change that might help them feel better in their running and life!