Dear Mark: Marathon Fuel, Muscle Cramps, and Another Dr. Oz Miracle

A few months ago I wrote an article on How to Fuel a Marathon. In this week’s Dear Mark, I answer a reader’s question on how to improve a hydration recipe I recommended in that article. Then I cover a somewhat related topic: muscle cramps, and how to fix them and how to prevent them. Finally, I discuss Dr. Oz’s latest supplement miracle product – raspberry ketones. Sounds delicious, doesn’t it? Let’s go.

Hi Mark,

I am in training for my first ever marathon and have read your how to fuel a marathon. I did try the homemade hydration drink on my training run last week of 24km. I had 2 bottles of hydration and 2 bottles of plain water. I found the drink very sweet and you can definitely taste the black slat molasses. Swigging water straight after did help but it wasn’t overly pleasant.

I thought I would give it a try as I plan to use it on my race day which is July 1st. I was thinking of reducing the black slat molasses to just 1 tablespoon to see if it reduces the very sweet taste and perhaps increase the raw honey to 3 tablespoons, to see if it’s more palatable. Would this have any effect on keeping hydrated?

Also what can I use to keep hydrated on my long training runs? I find water is just not enough and I get thirsty and start to hit the wall around 17km. So basically, how do you fuel your training runs?

It would be great if you could give me some advice on this.

Many thanks.


Cut the sweeteners in half. One tablespoon of each should work great and provide plenty of absorbable sugars, electrolytes and other minerals. I would caution against adding extra honey, as it’s actually far sweeter than the molasses, which has a distinctive taste but little outright sweetness. The honey, while imbued with plenty of phenolic compounds that may aid in general health, is really there to provide quick and easy sugar for your muscle glycogen stores. It’s not really giving you much hydration. The molasses is there mainly because it’s rich in calcium, magnesium, and potassium – all important electrolytes – and you don’t really need much more than a tablespoon to do it. To cut back on the sweetness, you could also use plain water instead of coconut water. And don’t forget the pinch of salt.

I don’t really fuel my training runs, because I don’t do them anymore. I’ll bring along a bottle of water, preferably mineral water or otherwise dosed with a pinch of salt, when I go for a long hike, but many times I’ll forget to even take a sip. If I had to choose something for pure hydration, water with a pinch of high-mineral sea salt and a pinch of potassium salt (often sold as “lite salt”) works. My old hangover pre-hab cure, which was designed to hydrate and which I’d always take before going to sleep after a night of drinking back in my younger days, consisted of water, sea salt, potassium salt, and the juice from one lime or lemon. I’d be willing to bet that would work really well, too.

I’ve always had muscle cramps in my legs and feet, but the more I eat PB, the more frequent the cramps get. This is the only thing that isn’t better in how I feel on this diet/lifestyle. Can you explain why this is happening? And possibly offer a suggestion to ease the cramping? Sometimes the cramping is so severe that it wakes me out of sleep and demands I immediately get up and try to stretch out the cramping muscle. Then it will hurt for days.


My first guess is that you’re just deficient in electrolytes. How’s your potassium intake? Your magnesium intake? How about calcium and sodium? Our interstitial fluid – the fluid that envelopes our cells, enables intercellular communication, and delivers materials to and from the cells – contains all four minerals. Properly controlled muscle contractions require good balance (especially of sodium, calcium, and potassium) in the interstitial fluid, while an imbalance of these minerals can lead to excessive muscle contractions, which can manifest as cramping. So, first off, monitor your electrolyte intake.

Good sources of potassium include avocados, sweet potatoes, potatoes, bananas, chard, spinach, and many more. Fruits and vegetables are pretty much the best sources. Fresh meat has potassium, too, but opt for rarer meat over well-done meat, as the potassium is found in the juices. Potassium, then, is really easy to get through food. You just have to eat some plants. Animals are important too (it’s “plants and animals,” after all), but Primal Coconut water is another good (and delicious) source.

Good sources of magnesium include leafy greens, nuts, halibut, pumpkin seeds, but some people find it difficult to get enough magnesium through food. In your case (lots of cramping), taking a good supplement is probably warranted. It seemed to help pregnant women with pregnancy-related cramping in one study. As for which form to use, most people stick with one of the magnesium “-ates,” like citrate, glycinate, or malate. This guy, on the other hand, had great success with sublingual liquid magnesium.

Sodium intake must also be considered. When people switch from a diet high in refined, processed foods to a diet high in whole foods that must be prepared at home, salt intake usually drops. Furthermore, some newly Primal people assume that Primal means “no added salt.” This isn’t the case at all, but the end result is that many people who go Primal end up taking in less sodium than before. Sodium is found in, well, salt.

You also have to watch your calcium intake. Leafy greens like spinach and collard greens are excellent sources, as is dairy, if you’re into that sort of thing. Yogurt is probably the densest source of calcium, and (in my opinion) it’s also the “safest” way to eat dairy – fermented. Bone-in sardines will also provide a nice whack of calcium, as will real, homemade bone broth (try to simmer it till the bones fall apart to ensure you’re getting all the minerals).

See the answer to the previous question and the referenced post for an electrolyte-rich drink that you can make for a quick remedy.

Are you very low carb – say, under 40 grams a day, enough to be a in a near-constant state of ketosis? Remember, ketosis has a diuretic effect, especially during the initial transition. With the water flush goes electrolytes, and if you never replenish them you’re likely to experience cramping. I’d also be curious about your activity levels. If you’re exercising a lot and really working up a good sweat, you’ll be losing even more water and more electrolytes. Carb intake should be tied to activity levels, as I always say.

You might also try getting more taurine. It’s a non-essential amino acid, meaning we make it ourselves, but supplementary taurine has been shown to help cirrhosis patients with excessive muscle cramping. As the best source of taurine is beef heart, this is the perfect opportunity to explore the wonderful world of offal!

Another, slightly more obscure possibility is the use of certain medications. Diuretics, statins, and long-acting beta-adrenoceptor agonists (or LABAs, used to treat asthma and chronic obstructive pulmonary disease) have been linked to an increased incidence of nocturnal leg cramps. If you’re taking any of those medications, they could be making the problem worse (or creating it altogether).

So, in summation:

  1. Eat leafy greens (and yogurt if you can).
  2. Use salt.
  3. Supplement with magnesium.
  4. Try knocking yourself out of ketosis; consider a carb refeed.
  5. Try taurine.
  6. Tie your carb intake to your activity level.
  7. Track your current meds and see if there are any potential conflicts.

I repeatedly notice that the Primal eaters who have the most problems are the ones who eat little to no plant material. While certain individuals can tolerate (or even thrive on) a total lack of dietary plant, the vast majority do better as omnivores.

Hi Mark,

Like many women, my wife is a Dr. Oz fan and has me view select bits that she finds interesting. Instead of constantly pointing out every flaw I see, I find it more productive to praise Dr. Oz (in front of my wife) for what he gets right.

We saw his segment on Rasberry Ketones and it sparked my interest. Have you looked into this? Can this supplement enhance ketosis for someone already in the 50-80 gram/day carb intake mode? Can it do anything for people with higher carb intake? Thanks.


Ah, the eminent Dr. Oz! If he says it, generally, I take it as gospel.

Seriously, though, it’s not total bunk. A study in rodents found that raspberry ketone supplementation both prevented fat gain on a proven obesogenic diet and helped already fattened rats slim down a bit. Sounds good, right? I mean, sure, we’re not big hairless, tailless rats, but we’re both mammals, and we can glean a lot of hints about our own physiology by studying rodents. Eh, not so fast: the rodents’ diets were up to 2% raspberry ketones. Yes, it wasn’t quite a supplement, it was a sizable component of their diets. That would be like if you swapped out polyunsaturated fat for resveratrol. When you’re measuring a supplement in calories, rather than micrograms, milligrams, or IU, I think it’s time to step away and reevaluate your relationship with the compound.

I suppose you could replicate the rat dosage and get 2% of your calories from raspberry ketones and hope for a result, but that would get pretty expensive really fast. The typical bottle has 60 capsules with anywhere from 100 to 500 mg per capsule, and you’d be taking at least half the bottle a day to hit the heroic dosages. Good luck.

That’s it for this week, folks.

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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