LCHF negates performance benefit of training. O_o

It takes about 3 weeks to become fully ketoadapted and you don’t really get more ketoadapted thereafter, at least as per max fat oxidation rates (which seems a pretty good surrogate, imo).

Important point: “Athletes who drop carbs cold turkey suddenly suck.”  And performance usually recovers by around week 3.  This has been confirmed in nearly every proper study on the subject, in a variety of contexts.



Which brings me to the latest alleged slam on keto & physical performance:

Low carbohydrate, high fat diet impairs exercise economy and negates the performance benefit of intensified training in elite race walkers (Burke et al., 2016)



The study design was adequate to assess the timeline of ketoadaptation, but not keto vs. high carb.  But they tried anyway…

Two confounders, on first glance.

First, these were lean young athletes.  Those on LCHF lost a statistically significant amount of weight and about 3 times more than those on high carb.


In lean young athletes without much fat to lose, it’s safe to assume some water &/or muscle loss.  NEITHER of those bode well for physical performance.  Imo, the researchers could’ve upped the calories in the LCHF group to keep body weight controlled, because the point of this particular study was PERFORMANCE not WEIGHT LOSS.



Second, performance declines in the first couple weeks of keto (P<0.05), so you can bet their training was inferior during this time… ergo, this result isn’t very surprising:


1- it’s kind of making a mountain out of a molehill: setting the baseline at 36 minutes makes the 190 second improvement look bigger than it really is given the large error bars.

2- keto did exactly as expected: performance plummeted then recovered back to baseline levels by week 3.  Now that they’re ketoadapted, we can expect an intensified training program to improve performance just like it did in the high carb group.  The researchers could’ve had ketoers ketoing for 3 weeks, THEN take baseline measurements, THEN take final measurements after 3 more weeks.  This would’ve more accurately assessed “the performance benefit of intensified training in elite race walkers” in keto vs. high carb, imo.  Sound reasonable?


oh well


calories proper


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  • rs711

    1st author Louise M. Burke also authored “Re-Examining High-Fat Diets for Sports Performance: Did We Call the ‘Nail in the Coffin’ Too Soon?” ( which is also rife with ‘bottom of the barrel’ sports-nutrition analyses.

    Massive error bars, shit design & a foregone conclusion (given her past papers)????

  • Jord

    How come every time a study comes out once again finding no benefit to ketosis on exercise performance; the “warriors” claim it was a bogus study, and other problems such as “not enough adaptation” or whatever else.

    There is more than enough evidence showing ketosis does not benefit any type of anaerobic sports, and will likely be detrimental.

    • Daz

      …must be because they are aerobic warriors

    • “not enough adaptation” is a BS argument: anything longer than 3 weeks is “enough”

      also, not sure “elite race walking” qualifies as anaerobic in this context, but still, no shortage of evidence in studies > 3 weeks

    • John Lushefski

      Elite gymnasts did fine on their keto diets.

      • Jord

        I would argue gymnastics is a skill; and elite gymnasts have likely been practicing the same movements repeatedly for 10+ years.
        But again, that is one study, showing they maintained strength.

        Where are the studies showing any kind of BENEFIT to performance, or at least maintenance of performance with any kind of sustained/repeated anaerobic activity?

        There does not seem to be any.
        Why do people seem to think they can get some kind of performance benefit for doing this?

        • Daz

          If there are any studies showing benefit, it would more likely to be aerobic sports.

          Some sports I’ve seen mentioned, tho probably via blogs rather than studies (cannot recall);
          Speed skating (not sprints I presume).
          Walking (personally I do not see that as a sport. But it is in the Olympics).
          Ultra marathons.
          Cross country skiing.
          Distance swimming (crossing the English channel would be a good one).

          Then you have sports like Cricket & Golf, not much anaerobic stuff going on there.

        • And why is that a problem? It really boggles my mind that people think you need to follow 70% percent fat ratios if you want to do Keto.
          Unless you’re epileptic there is no reason not to have a higher protein intake, since it helps with body composition and performance.

  • Man

    Good study or not, what really matters is how as an elite athlete you perform under various diet regimens. If keto works out for you, then OK, keep doing it. As far as I am concerned, I am neither an elite athlete nor a keto-warrior. I love eating good natural foods with plenty of carby items. i feel best that way, I am at the strongest and fittest time of my life, and I look the greatest naked at the age of 42 when I compare with myself at any time in the past. Good nutrition, solid workout program, sunshine and clean sleeping habits with little overall stress are what I found matters most for me.

  • Matthew Klein

    I wonder how water balance and electrolyte intake could have played a role here. If the LCHF group was low enough in carbs and wasn’t intaking extra salt I think that could seriously have impacted their performance.


    I’m sorry, elite race walkers?

  • Daz

    (test comment…previous comment may have got stuck in spam folder I think)

  • Daz

    On the same topic,
    suppversity .blogspot .com/2017/02/low-carb-diets-and-physical-performance.html