Can a Ketogenic Diet Make You a Better Ultra Runner (Part 1)?

  • You bet.  Going ketogenic (or even just low-carb) has a number of benefits that directly improve your performance as an ultra endurance athlete
  • Being in ketosis improves your body’s ability to burn fat as fuel, critical when you’re running for over 24-hours
  • Ketogenic diets are anti-inflammatory, reducing the wear and tear on your system and increasing your recovery speed

If you’re reading this, you’re probably already considering going low carb or even all the way to ketosis – with hopes of improving your performance as an ultra runner.  My recommendation: jump right in and try it out. I’m confident you’ll be amazed at the results.

As you probably already know, ketosis is a state when your body has switched over to operating nearly completely on fat.  If you consume very few carbohydrates, your liver starts producing “ketones”, these magical, little molecules that come from fat stores and act as an alternative fuel for the body.  Before the world was awash in white chocolate chip pancakes and venti frappuccinos like we are now, ketosis was likely a pretty normal state for humans.  You ate food, that food was stored as fat, and then your body tapped into that fat to power you throughout your paleolithic day, hiking across the savannah and whatnot.

Here’s the great news: a ketogenic diet has a number of amazing benefits that will help a fat-adapted ultra runner perform at top levels.

Weight loss.  Most people on keto lose some weight.  It makes sense – you’re burning those fat stores that your body has been hanging on to for a “just in case” survival moment. I am relatively thin, but I still used to carry around some pudge in my mid-section, even while logging 60-70 miles per week.  Ketosis melted it away.  Trust me – you’ll get lean.  And this means reaching your optimal racing weight.

Fat as Fuel.  The conventional wisdom says that during exercise you need 250-350 calories per hour, usually all carbs.  In a 100-miler, that means you’ll need to eat 8,400 calories during a 24-hour race!  That’s 84 packets of GU, folks.  No wonder you hear about people’s stomachs rebelling.  Ketogenic runners rely on their body fat instead, with a small amount of supplemental fueling during the race.

Mental Focus.  There is a common misperception that the brain needs carbs.  Not true. The brain not only can run on ketones, but there is a lot of evidence that shows the brain prefers to run on ketones.  Without the huge swings in blood sugar associated with overloading your system with carbs, your brain doesn’t have those “sugar high” moments (and crashes) and has an opportunity to focus on the important things.  Like your race performance.

Faster Recovery.  Ketogenic diets are anti-inflammatory.  Why is this important?  Over the long term, this will help reduce the possibility that you will get serious illnesses associated with chronic inflammation.   In the short term, this will help you recover from the massive amount of inflammation you will inflict on your system over the course of 100-miles.  That means less wear and faster recovery for your body.


How do you do it?  In order to go into ketosis you’ll need to reduce your carbohydrates by a lot.  Everyone is different, but you’ll likely need to get your carbs down to under 100g per day, more likely to under 50g per day. For people with a sweet tooth, that restriction is not easy.  There are 31g of carbs in a glazed donut.  But trust me – you’ll get used to it quickly and pretty soon the entire way you look at food will recalibrate.  Oh – and did I mention that you don’t have to worry about calories nor will you ever feel hungry?

Going ketogenic also requires a little bit of a nutritional “un-brainwashing” – you have to be willing to throw out a lot of the conventional wisdom that’s been doled out by nutritionists over the past half a century.  Gems such as “fat is bad for you”, “runners need carbs”, and “calories in should equal calories out” all need to be looked at with healthy skepticism.  I would highly recommend reading a couple of key books that will be the cornerstone of your re-education:

booksSo you’re probably wondering – does it work?  Certainly you can look to elite low-carb superstars such as Zach Bitter and Tim Olson for inspiration.  But those guys are also just amazing freaks.  Sometimes it’s tough to draw a clear parallel from that level of athlete to us mortals.

For me, it works.  Here’s what happened.  After being on a low-carb diet for about two weeks, I finally went into ketosis.  That weekend I went for a 31-miler, consuming only two Justin’s almond butter packets at miles 10 and 20.  Interesting, I thought.

Feeling confident, but wondering if it was just a fluke, I decided I needed to try the keto system out on a longer run – the Rocky Raccoon 100.   During that race I maintained the same fueling strategy – nut butter packets every 10 miles (complimented by a few sausage links at the aid stations).   The result: pure, sustained energy –  and a sub-24 hour finish.  I had been in ketosis about a month.  Needless to say, I’m convinced.

More to come.

For more, here’s a good keto primer: A Ketogenic Diet for Beginners


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