Fat Adapted: A New Diet For Ultra Running?

May 22

Fat Adapted: A New Diet For Ultra Running?

Talking to a few fellow ultra runners this past weekend and a few other friends about diet/nutrition the subject got on being fat adapted.  This is something that I’ve heard about here and there on the Endurance Planet podcast especially from Ben Greenfield.  The basic concept is that the body has two fuel sources carbohydrates/sugars or fat.  Most endurance athletes use a combination of both of these but will normally rely mostly on carbohydrates for training and racing and will utilize fat during extreme events or when they “bonk” the feeling that happens when your body runs out of readily available carbs and has to switch over to burning body fat as fuel.

The concept of being Fat Adapted is that you rely more on body fat as a your main fuel source so you are less reliant on carbs and refueling.  I am still learning a lot about this concept and most knowledgeable people that I have heard or read about are of the opinion that being fat adapted or utilizing carbs is not a right or wrong concept that if you are utilizing carbs that there is nothing wrong with this however, some athletes can benefit from being fat adapted verses normal carb based diet.

I am going to try and see if I can first, become fat adapted and then see if there is a positive effect on my daily life and running performance.  I will try and keep you updated on how this goes and how my attempts to become fat adapted turn out.  I have not found a specific plan for becoming fat adapted so what I have found as as follows:


  1. Limit your carbohydrate intake to 50g or less a day.
  2. Reduce your protein intake. (exact amounts not found)
  3. Increase your fat intake. ( I will try to do this with moderate animal fat and more avocados, nuts and olives ect…)
  4. Drink lots of water.
  5. To accelerate work on depleting your body of glycogen through fasting or exercise.  I’m going to opt for exercise, which basically means I’ll be doing a lot of bonking.


Here are some of the resources that I have been referring to if you have others or have done this already I would love to hear your experiences.

Info Resources:

Mark’s Daily Apple Post: Part I

Mark’s Daily Apple Post: Part II

Endurance Podcasts:

Podcast I

Podcast II 

Fat Adapted Blog



  1. Hey you looked into the OFM Program by Vespa Power Products? I am following the plan and have had good results. Zach Bitter beat the World Record for the 12 hour time for ultra running following the plan.

    • Jordan /

      Stephanie, I have have not used Vespa or UCann type products but I have heard a lot of positive comments from athletes. I did a fairly strict fat adapted diet and had some very positive results. I have followed a lot of what Zach has done and his dieting and protocols and it is pretty amazing. I think the one draw back for my with Vespa or UCann type products is the expense but I may have to give them a try, might be worth the money.

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