Dear Mark: CrossFit and Carb Questions

Inline_DM_07.10.17For today’s edition of Dear Mark, I’m answering questions from the comment section of last Thursday’s post on CrossFit, Primal, and carbs. First, I use a comment from Dave to expand on the idea of earning your carbs and eating the carbs you earn. Second, I discuss the notion of athletes using cyclical low-carb diets. Would their performance suffer? And finally, I go over a few more starchy carb sources allowed on the Primal eating plan that I forgot to mention last time.

Let’s go.

Dave mentions:

My only issue is that after a lifetime of being overweight my initial instinct is always to restrict carbs when in fact I know that I need more.

Dave, your comment reminded me of something I meant to discuss.

Everyone’s familiar with the idea of “earning your carbs.” If you’re going to eat a lot of carbs, you should earn them by depleting glycogen. Other ways to earn carbs include getting pregnant, being pregnant, and breastfeeding. There’s a subtle flip-side to that, which few realize: If you earn the carbs, eat the carbs.

Folks who kill themselves in the gym, then ignore their bodies’ request for dietary glucose aren’t doing themselves any favors. I love gluconeogenesis as much as the next guy, but if gluconeogenesis can’t keep up with your carb demands—and CrossFit WODs create quite a demand—you should eat some carbs. Refusing to eat carbs when your depleted muscles are screaming for more creates a stress response. That means cortisol, which triggers gluconeogenesis and in excess, blunts fat loss, opposes testosterone, and promotes belly fat accumulation.

Less fat loss is bad for obvious reasons. Almost everyone in this fitness/diet game came because they wanted to lose weight, which really means they wanted to lose body fat. Chronic high cortisol is terrible for that.

Less testosterone is bad for fitness and physique gains. That goes for men and women, by the way.

Belly fat is terrible for your health. Adipose tissue is an endocrine organ in its own right, and belly fat secretes large amounts of IL-6, an inflammatory cytokine strongly correlated with systemic inflammation.

Some worry about the insulin response. I don’t blame you. Hyperinsulinemia and insulin resistance are major issues in the modern world. Most people should be trying to limit insulin. But if you time your carb intake right, and you’ve just trained hard, you won’t even need very much insulin to shuttle that glucose into those muscles. You’ll trigger a little pathway called non-insulin dependent glucose uptake, leaving your body free to liberate stored body fat as needed. See how things work out when you earn your carbs then eat them?

Joe wonders:

I’d like to know if someone is fat adapted and employs a cyclical or targeted ketogenic diet can get the same or better results doing competitive crossfit as someone who eats a high carb diet. Any thoughts?

I doubt you’ll see any top Games competitors going cyclical keto. It might work. They just probably wouldn’t take the chance.

That said, I think it could work if you were meticulous about it. And I know that fat-adaptation is going to help any athlete. Everyone can benefit from wringing as much intensity as they can out of fat-burning. Everyone benefits from having a little more glycogen saved for the end.

There was the study I referenced last week where elite walking athletes either went low-carb/high-fat, high-carb/low-fat, or cycled low-carb and high-fat. Both the high-carb and cyclic low-carb groups beat the low-carb group. So clearly cyclic can work, at least for elite race walking. That’s not CrossFit, but it’s the best we have to go on.

Let’s keep a few things in mind when analyzing this study.

The low-carb, high-fat athletes lost a lot of weight. They didn’t set out to lose weight. They were already lean and healthy—elite athletes, remember? When the obese lose weight, performance improves. They’ve got extra weight to lose. When the fit and lean lose weight, performance often suffers. They don’t have anything to lose, so lost weight probably comes from muscle. Allowing ad-lib eating rather than isocaloric eating, as happens in real life, could have prevented the weight loss. Alternatively, the researchers could have added calories to the low-carb group to avoid weight loss.

The study ran for 3 weeks. Three weeks is the bare minimum for an athlete to become keto-adapted. I’d like to see this same study extended for a few more months, allowing optimal adaptation to the diet.

Yet the cyclical low-carb group did just as well as the high-carb group.

Marge mentions:

There are so many more primal sources of high-carb, high-energy foods than are mentioned here… Don’t forget winter squash, turnips, parsnips, beets, plantains… And if you need calorie-density, fry starchy things such as potatoes and plantains in bacon fat til they are crispy! Delicious, nutrient-dense, and sustaining fuel! Use your food imagination!

Yeah, I forgot a few. Thanks for the reminder. I’ll go over the ones you mention, then maybe add them back to the original post.

Winter squash. Underrated. These are the perfect starch source for the person who’s still not quite sure about eating more carbs. A cup of cubed butternut squash contains 16 grams of carbohydrates. Compare that to a cup of cubed sweet potato with 27 grams, or a cup of diced white potato with 28 grams. Winter squash also tends to be a good source of magnesium, potassium, and manganese.

Beets. A cup of beets contains around 13 grams of carbs, mostly sugar. About half of sugar ends up refilling liver glycogen, with the rest being available to muscle glycogen, so beets are fair sources of carbs for athletes. Beets are also good source of potassium, manganese, and folate. Most importantly for athletes, beets have a ton of nitrate, which can boost nitric oxide production and improve endothelial function and blood flow, and improve athletic performance:

Not bad, right?

Parsnips. A cup gives you almost 24 grams of carbs, plus a good dose of magnesium, potassium, manganese, and folate.

Turnips don’t make the cut. They’re perfectly good to eat, just not as a reliable source of starchy carbohydrate.

That’s it for today, folks. Thanks for reading, and keep the questions coming!

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About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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12 thoughts on “Dear Mark: CrossFit and Carb Questions”

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  1. One of the questions I had following this discussion is about non-elite athletes. If you do crossfit and do it regularly, let’s say 1 hour of crossfit styling working out 5 or 6 times a week, does that merit changing the way you eat within the Primal framework? It’s still higher intensity than I think most people are doing, but not quite Crossfit Games competitor level. Where is the divide? How can you identify for yourself if you should be eating more carbs or not?

    1. Are you bonking during your workout? You probably need more carbs.

      1. Bonking could be a few different things….sleep…lack of hydration…electrolytes. Tough to say without knowing more.

  2. Thank you for addressing those issue. The 1st question really hit home. After staying trim and holding my weight for the last 5 years, I suddenly gained weight and belly fat. The only explanation I can think of, other then being out of commission for several months due to a multi stress fractures (I ended up sitting a lot), is that I took my carbs limitation to the extreme and paid dearly. However, I already started to correct for that. Live and learn….. and try not to get hurt while doing it 🙂

  3. I SO appreciate the timeliness of these carb discussions. My mother, who is fairly paleo/primal and severely underweight, needs to eat more carbs to put on weight before impending heart surgery, quite a task when most paleo and primal blogs and literature are all about cutting carbs to lose weight. All of these good carb sources make a handy list that she can eat from at each meal.

  4. I wouldn’t describe winter squash (pumpkins, etc.) as high-carb foods.

    100gms of pumpkin has six net carbs. A pretty decent serving of 300gms only has 18. Combine that, say, with 400gms of cabbage and some protein and you have a hefty dinner with about 32 net carbs. Not exactly going to blow your insulin response through the roof.

  5. Naive question: I’ve recently transitioned to Olympic-style lifting; how much does this training modality deplete glycogen? It doesn’t spike my appetite quite as much as crossfit-style workouts, but I would think explosive compound movements would probably deplete glycogen. As always, the Internet offers conflicting answers!

    Thanks for the timely post as always — I was reading after finishing a post-workout steak and craving some carbs…

    1. O lifts aren’t traditionally glycolytic in nature. As you may know, if you’re doing singles, doubs or even trips, you will be primarily using the creatine phosphate (CP) energy system as long as you have adequate rest / recovery between sets / lifts. On days where you perform more complexes, you may be more glycolytic but if the entire complex takes you less than, say… 10 seconds, you’re still primarily using CP. In this instance, carbs aren’t going to make much difference but it’s still worth experimenting and finding what works best for you.

      I personally need my carbs to recover my CNS. If my CNS is under recovered, forget about it… just can’t drop under the bar fast enough.

  6. Mark,

    Thank you for the detailed response to my statement. Sometimes the body can change more rapidly than the mind. My sweet potato and green banana consumption will be calibrated for my heavy lifting days, I just need to silence the “fat guy” who intermittently taps on my shoulder during meal preparation.

    A quick aside , no matter how drastically my appearance has changed I am unsure that I see what others see. It is as if that residual silhouette of who you once were never truly vacates your psyche. It is useful in a sense that it keeps one humble, modest and provides perpetual motivation to improve. It can also be a hinderence because it makes any feelings of success elusive and fleeting.

    However, it is a marathon and not a race.What a learning process this has been. Outside the vanity aspect this lifestyle also provides fresh mental trajectories, a vigorous supply of confidence (often where non previously existed) and a compelling desire to reciprocate.

    Thank you again for the reply…..

  7. I’m absolutely loving all the primal stuff and hope to get into the coaching stuff very soon. My reason for trying the whole thing out was to become fat adaptive for next year’s marathon des sables. In 8 weeks I’ve probably nearly lost a stone and feel great. Interestingly reading about the carbs I was probably being too strict and not consuming enough and bonked quite seriously on some long slow aerobic rides. I now understand that I need to add more carbs on these demanding days. Thanks. Paul

    1. Thanks for the response Mark. Interesting study although, like you said, speed walking is far from crossfit. It’s good to hear that you think cyclical keto can possibly be used by competitive crossfitters. It would be nice to get all the benefits of a ketogenic diet without having performance suffer. I think I’m going to give it another try even though my first go around with a standard keto diet wasn’t very successful.

  8. Every crossfitter I know has wound up injured and burn’t out – just an observation…