Are low-carb diets good for high-intensity training?

Women training with corde

Probably.

For an even lower-carb ketogenic diet, maybe.

It’s a controversial topic within the sports nutrition sphere. We should already know, but don’t, in part because of the corrupt practices in the sports nutrition industry (check out Tim Noakes’ book for an example [1]).

What 2 studies say about training low-carb or ketogenic

One 2006 study said sprint times of cyclists doing a high-intensity 4 kilometer time-trial were significantly slower on a low-carb high-fat diet than when on a high-carb low-fat one [2]. However, performance in a 100 kilometer event was not affected by the diets. There are 4 reasons I do not take this study’s conclusions about low-carb high-fat diet being worse for ‘sprinting’ at face value.

First, the cyclists didn’t have enough time to adapt to their low-carb high-fat diet.

Second, the difference in times is statistically iffy (8 cyclists per diet group isn’t enough to be sure).

Third, both diet groups were given 20g of a sugar drink every 20 minutes, which confounds the diet intervention (i.e., is it the diet and/or the sugary sports drink affecting results?).

Fourth, the study is partly funded by Bromor Foods Pty. Ltd. [3] which manufactures non-carbonated soft drinks.

This is a potential conflict of interest given the dodgy history of the sports drink industry influencing the science of sports nutrition.

On the other hand, a 2013 study [4] measured the power output of people doing a Wingate test when either on a low-carb high-fat diet or a high-carb low-fat diet. A Wingate test is a very high-intensity kind of effort (see for yourself [5]). The diets did not significantly change their peak power output.

There are many more ‘pro and con’ studies to out there. Whether a low-carb high-fat diet is good (or just appropriate) for high-intensity (aka glycolytic) training is still an open question. The trend I see is that the better designed the study, the more it tends to suggest ‘carb-loading’ is not necessary for explosive efforts.

4 tips for your low-carb or ketogenic diet experiment

Try it out. Do so with the following tips in mind:

  1. give yourself time to adapt (preferably a few weeks “pre-season”)
  2. food quality still matters when changing the ratio of fat-to-carbs (macros)
  3. results from your self-experiment (aka N = 1) will be affected by other factors you cannot control (so take them with a grain of salt)
  4. talking about salt…when transitioning into a low-carb high-fat (or ketogenic) diet, take in enough electrolytes! (check out Keto Gains’ excellent Food Pyramid [6] for a How To)

Go low-carb, see if and how your Crossfit WOD [7], basketball or soccer game changes. Like most recommendations from Break Nutrition, if the available science suggests it’s safe and reasonably likely to benefit you, we say go for it!

Go break some nutrition myths!

 

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