Remembering Kevin Moore

ATLCX (Episode 37): Ben Greenfield | Ketogenic Diets And Exercise Performance


In Episode 37 of “Jimmy Moore Presents: Ask The Low-Carb Experts,” we are pleased to address the topic of “Ketogenic Diets And Exercise Performance” with one of my fellow health podcasters who just so happens to be a low-carb triathlete named Ben Greenfield. Carbohydrate loading has become so deeply-ingrained (all pun intended!) in our culture for endurance athletics these days that hardly anyone questions whether or not it is the most effective means for fueling exercise performance. But ketogenic diet researchers like Dr. Stephen Phinney and self-experimenters like Dr. Peter Attia have discovered a new paradigm that could quite possibly be the future of fueling exercise activity–using ketones as an alternative and much more preferred energy source for fueling exercise. We were pleased to have a bona fide expert on this topic in sports scientist Ben Greenfield from “Ben Greenfield Fitness” (listen to my interviews with Ben in Episode 609 and Episode 457 of “The Livin’ La Vida Low-Carb Show” podcast) joining us in EPISODE 37 to talk about the important topic “Ketogenic Diets And Exercise Performance” that aired LIVE on January 31, 2013.

Listen to Ben Greenfield take questions about low-carb and exercise:

  • Traditionally, sports performance relies on glucose for fuel
  • Glucose is a great fuel source for doing sports/workouts
  • But there is a health vs. performance trade-off here
  • If you load up your body with carbs, insulin gets turned out
  • Blood sugar fluctuations are the norm and that is harmful
  • Insulin insensitivity sets in and free radicals produced
  • Fats become oxidized and increased levels of triglycerides
  • Sugar is like a “drug” on exercise activity, but not needed
  • We can rely on fatty acids for fuel (like ketone bodies)
  • It’s very difficult to get away from carbs for fuel
  • But the body can create ATP-based energy in keto-adapted state
  • We need far less levels of glucose than we’ve been told
  • If you’re going to have glycolitic efforts, you still need it
  • But the glucose requirements are still very minimal
  • He’s made the switch from high-carb triathlete to low-carb
  • He’s racing faster now and not damaging his body anymore
  • The carbohydrate fermentation is no longer happening
  • Listen to ultra-marathon runner Tim Olson on The LLVLC Show
  • You have to be careful with nut butters that are roasted
  • Better to have a few raw almonds than roasted almond butter
  • Omega-6 fat concentration in these can be harmful
  • Novak Djokovic and Kobe Bryant seem to be keto-adapted
  • Many people don’t know muscle is comprised of fat cells too
  • You can grow muscles by eating more dietary fat
  • Even my reduced amount of protein intake, I put on muscle
  • Maximum performance is going to rely on fuel and body comp
  • Ketogenic diets come in handy for proper weight management
  • Pushing yourself to lactate threshold without glycogen depletion
  • Goal of ketogenic diet isn’t to deplete body of glycogen
  • Body can take ketones and convert them into glucose for energy
  • Your body can tap into what’s stored away in the muscle itself
  • For an ironman athlete, 150g carbohydrates/day is upper level
  • Ketogenic diet is not synonymous with liver/glycogen depletion
  • You’ll be able to tap into storage carbohydrate even in ketosis
  • If you’re eating zero carb, then perhaps that will cause issues
  • What kind of foods he consumes in 40-150g carbohydrates
  • Sweet potatoes, yams, fruit, white rice, seeds, nuts, raw dairy
  • Fermented soy and sometimes a sprouted quinoa, chia seeds
  • What a Respiratory Exchange Ratio (RER) is and its purpose
  • It shows what your primary fuel source is: carbs vs. fat
  • The test can be influenced by what you ate days before
  • Yes, women can succeed on a higher-fat intake naturally
  • Study examining ketogenic diet in elite gymnasts
  • Whether artificial sweeteners can impact ketosis
  • There are potential gut toxin effects damaging gut flora
  • That could technically impact your carbohydrate absorption
  • There’s no data that it impacts exercise performance
  • He doesn’t consume any sports foods with artificial sweeteners
  • Sarcoplasm is the fluid that surrounds the actual muscle
  • Muscle has glycogen, but can use fat stored for fuel too
  • You’re putting the body into a state to tap into fatty acids
  • It will spare the glycogen until very high intensity reached
  • What rhabdomyolysis is and why it’s harmful
  • A high-protein diet doing an ironman makes you susceptible
  • Higher protein intake leading up to the event can be bad
  • Don’t get anywhere near 200g protein to give body what it needs
  • Try getting about .7g per pound of body weight
  • Use ketone strips before and after exercise to test ketosis
  • You want to be at 1.0 millimolar ideally to fuel exercise
  • He uses pre-digested amino acids during his races
  • Some MCTs as well as UCAN SuperStarch helps as well
  • Whether carb-loading later in the day is best
  • Getting your carbs spread before, during and/or after exercise
  • Shoot for 200-250 calories worth of carbs during training
  • A day prior to the event, some extra carbs is good to do
  • Depending on the marathon, you may not need the extra carbs
  • What is different about doing ketogenic diet for ectomorphs
  • Ectomorphic types are able to tolerate more carbohydrates
  • Robb Wolf’s posts on ketosis/performance Part 1, 2 & 3
  • Just because a sport is glycolytically demanding…
  • That doesn’t mean you never use glycogen for energy in ketosis
  • If people have not become fat-adapted, you can feel blah
  • There’s a temporary dip in performance in ketogenic state
  • But getting plenty of sodium balance and other things
  • He plays tennis just fine because he gives himself enough fuel
  • His creates glycogen from protein, ketones and “sane” glucose
  • The body can create 400 calories of glucose from ketone bodies
  • Listen to Paul Jaminet in Episode 36 of ATLCX
  • The higher the intensity of the race, the worse ketogenic is
  • Optimal ketone zone is 1.0-3.0 millimolar during the race
  • If you are not showing any ketones at all, you’re sugar-burner
  • Non-starchy vegetables should not be interfering with ketosis
  • It could be a protein issue if he’s eating too many
  • He’s testing his urine but not his blood ketones
  • Ketoacidosis is about 10.0 millimolar and with Type 1 diabetics
  • I’ve seen some 4.0 readings and higher–but not close to 10.0
  • There’s no added benefit of going above 3.0 before exercise
  • If you want to feel really good, don’t get super high in ketones
  • We don’t know if this is an issue for non-Type 1 diabetics
  • Even Tim Olson isn’t doing ketogenesis per se in running
  • Usain Bolt won’t be getting the burst of energy in his racing
  • Ketogenic diets are not necessary for exercise performance
  • Check your method of measuring ketosis for accuracy
  • If you are doing intense exercise fasted, you break down muscle
  • Test your body fat percentage to see if you’re muscle-wasting
  • If body fat doesn’t change and lean mass drops, losing muscle
  • Taking 5-10g essential amino acids (it’s about $50 per bottle)
  • You could train 20 hours/week for an ironman race in ketosis
  • Make sure you are getting an adequate amount of glucose
  • Stay relatively low-carb during the day, then carbs at training
  • It’s possible to gain muscle on a low-carb diet
  • If you’re doing 60-90 minute sessions, you should cycle carbs
  • This might push you out of ketosis on those lifting days
  • You’re still not “shoving as many carbohydrates” as you can
  • Maximum of 150-200g on these super lifting days
  • On an easier day of exercise, very low-carb is the norm
  • You still build bone and strength doing higher reps
  • Lifting lower, heavier weights will develop “boulder” strength
  • Listen to Ben Greenfield’s outstanding health podcasts
  • Come to “Become Superhuman” conference March 8-9, 2013
  • Enhancing your body, health and mind is the goal of this
  • His Ironman Canada quest with minimalist training, ketosis
  • He wants to “biohack Ironman” race competition
  • We will be gone for the next couple of months
  • I’m writing a book on reading cholesterol test results


    There are five ways you can listen to Episode 37:

    1. LISTEN LIVE ON THURSDAY NIGHTS AT 7PM ET by calling (712) 432-0900 or on Skype at “freeconferencing.7124320900”–whether you call or Skype, be sure to use the access code “848908.” You can listen and even participate on the topic discussion by asking your questions directly to the featured expert.

    2. Listen at the iTunes page for the podcast:

    3. Listen and comment about the show at the official web site for the podcast:

    4. Download the MP3 file of Episode 37 [62:52m]:

    5. Listen on the Stitcher app–NO DOWNLOADING!

    If you cannot join us LIVE on the podcast on Thursday nights at 7PM ET, then you can still ask your questions of the expert guests by e-mailing them to us directly at AskTheLowCarbExperts@gmail.com. Be sure to include your name, the name of the expert you want to ask your question to in the subject line, and your question on the specific topic of discussion. This is a golden opportunity for you to tap directly into the wealth of knowledge and experience on all things related to healthy low-carb living featuring the best and brightest experts in the realm of health!

    How did you like what you heard from Ben Greenfield regarding the role ketosis can (and perhaps should) play in maximizing your ability to perform in your chosen exercise activity? We always appreciating hearing what YOU think and you can do that in the show notes section of Episode 37. This was our final episode of “Ask The Low-Carb Experts” for at least the next couple of months while I’m writing my new book, so be sure to check out the archives section in case you missed any of our outstanding previous episodes. I promise when I return in a few months we’ll have more amazing topics and expert guests for you to enjoy.

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    • I consume very little carbohydrate – on some days, virtually none. I regularly cycle 50+ miles on my VLC diet. I did a century ride a few months ago with the first 75 miles in a fasted state, then ate steak and eggs and finished the 100 miles with energy to spare. This, I know, is a broken record, and I keep bringing it up along with the fact that I will be 60 in March.

    • LLVLCBlog

      Congratulations on being able to handle that big bolus of carbs. Most here cannot.

    • saicho bob

      i have listened to the podcast, but talking “ketogenic” with those amounts of carbs is far away from what i understand from other experts. of course we are all different.
      thanks for getting my question on.

      • LLVLCBlog

        Depends on the individual for sure.