Six ways to kick nasty leg cramps to the curb

Do you experience crippling leg cramps on your low-carb keto diet? Do you awaken in the night with a sense of dread as the unmistakeable tightening starts to creep over toes, a calf muscle or a foot arch?

Fortunately, leg cramps don’t happen to everyone on the low-carb, keto diet. However, if they do happen to you, that early tingling can suddenly harden into a full-blown, agonizing charley horse that sometimes feels like it will tear the muscle off the bone. The muscle soreness can last for days. Some people experience legs cramps on a nightly basis, contributing to severe insomnia and increasing their night time risk of falling.

If this happens to you, this guide will help. We’ll go into six key things to explore to get leg cramps under control.

Nocturnal leg cramps are a common complaint in medical practices even among people not eating a low-carb or ketogenic diet. The medical literature estimates that up to 33 percent of all adults over 50 experience their pain (and the resulting distress and disrupted sleep) on a regular basis.1

Among low-carb and keto-eaters, while there are no hard estimates to the number afflicted, increased frequency of leg cramps are known to be a common side effect of the diet.

Here are the six key things to know to kick your leg cramps to the curb:

1. Magnesium deficiency is rampant

Most leg cramps arise because of a magnesium deficiency. Magnesium is a crucial mineral that the body needs for more than 300 enzymatic reactions, including muscle contractions and neuro-muscular conduction of signals.2

“Magnesium calms muscles (including the heart), nerves and the brain. When magnesium levels fall in these organs, they get ‘twitchy’,” explain Dr. Stephen Phinney and Jeff Volek in their book The Art and Science of Low Carbohydrate Living.3 The mineral is so important to muscle and physiologic functioning that Phinney and Volek devote almost three pages to it in their book.

“Cramps during or after exercise or at night are a sign that your body has a major magnesium deficiency,” they write.

Subclinical magnesium deficiency — meaning the deficiency is not yet showing outward symptoms — is a significant issue in the population at large. It is estimated that almost 50 percent of the US population may be magnesium deficient.4

So why does low-carb eating suddenly bring on leg cramps or make them worse? It’s because the low-carb keto diet shifts the balance of our electrolytes, particularly salt and potassium. That electrolyte shift unmasks the pre-existing magnesium deficiency, explains Dr. Jay Wortman, a Vancouver physician who experienced his own battle with crippling leg cramps when he first started the low-carb diet almost two decades ago. He solved the problem by magnesium supplementation

Testing for magnesium deficiencies is challenging and unreliable. Standard blood tests measure serum magnesium, but what really matters is cellular magnesium levels, and those may be low well before it shows up on a blood test.5

Our main source of magnesium — the food we eat — may not be sufficient for our needs because of the depletion of the mineral in our soils through modern agriculture and from low levels of magnesium in processed foods.6 As well, cooking methods can reduce the amount in food even more.7 To get the most magnesium out of your foods, don’t overcook vegetables, use the drippings from roasted meat, make bone broth or keep the water that vegetables have been cooked in and use it for soups or sauces.

Low levels of magnesium are associated with many health conditions including type 2 diabetes, insulin resistance, metabolic syndrome, cardiovascular disease and hypertension.8 These are precisely the conditions that many of us come to the low-carb diet already suffering from, so many of us are magnesium deficient from the very start, even before we start eating low carb.9

Supplementing magnesium

Starch structureAs long as you don’t have kidney failure oral supplementation of magnesium is the most reliable way to ensure you are getting enough. But it can take some work to find the supplement that works best for you.

There are several types of oral magnesium available, including magnesium aspartate, magnesium citrate, magnesium chloride, magnesium lactate, magnesium malate, magnesium taurate, magnesium gluconate, magnesium glycinate and magnesium oxide.10

Magnesium supplements can cause diarrhea for some people, which can reduce the amount of magnesium absorbed. New research suggests the most easily absorbed versions, that may be the least upsetting to the digestive tract, are glycinate, malate and taurate — but those GI results can be very individual.11 Magnesium citrate and magnesium oxide are routinely used as “osmotic laxatives” — meaning they pull water from the intestine wall — and so are most likely to trigger diarrhea.  You may have to experiment to find the type you tolerate best.12 Of course, for individuals who suffer from constipation on the low-carb keto diet, the laxative effect of magnesium may be a welcome side effect.

Topical magnesium oils and lotions, or magnesium sulfate (Epsom salts) that are absorbed through the skin are easier on the stomach — but there is great debate in the medical literature whether topical applications of magnesium can be absorbed in enough strength to actually improve significant deficiencies.13 If you can’t tolerate oral supplements, however, topical magnesium products may be worth a try to see if they help your leg cramps.

Here is another factor to consider: the quality and effectiveness of commercial magnesium formulations vary significantly., a company that independently tests supplements to verify label claims, recently tested more than 40 magnesium formulations and found many supplements contained less magnesium than claimed or did not disintegrate properly after being swallowed, reducing the amount absorbed. (As well, some supplements even contained lead.) Phinney and Volek note that one popular oral supplement, magnesium gluconate, actually contains more carbohydrates than magnesium.

If you’ve been taking magnesium regularly but it has not been solving your leg cramp problem, you may not be absorbing enough and may need to adjust the type of magnesium or the way you take it.

How to get more magnesium

Here are our best tips for upping your body’s magnesium stores.

  • Take a slow-release magnesium supplement for at least 20 days: Phinney and Volek have created a protocol for leg cramps in which you take three slow-release magnesium tablets a day for 20 days. Slow release formulations include Mag64, Slow Mag, or Mag-Delay. (These formulations are available in the US, but sometimes not in other countries. Ask your local pharmacist if there is a slow release version in your region.) If the cramps return after a month of slow-release supplementation, do the protocol again, and then continue taking one pill a day. If cramping still continues, take two slow-release pills a day in perpetuity.
  • Take daily one-third the dose of milk of magnesia: Dr. Eric Westman recommends that his patients take a small daily dose of milk of magnesia (magnesium hydroxide), about 1 teaspoon a day, which is one-third the dose used for its laxative qualities. This small amount will not cause most people to have diarrhea but will up the amount of magnesium you absorb.
  • Try absorbing magnesium through the skin: A regular bath with Epsom salts (magnesium sulfate) is a relaxing way to soothe sore muscles and may help increase your magnesium stores, in addition to oral supplementation. You can also try massaging magnesium infused oils or lotions into the skin. As noted above, however, research to-date has not proven the effectiveness of this.14
  • Drink mineral water with magnesium: Some mineral waters have very little magnesium, but a few brands are very good sources of elemental magnesium which is very easily absorbed and easy on the stomach. A mineral water is considered to be a source of magnesium if it has a magnesium content of at least 50 mg per liter.15 Two widely available German mineral waters are particularly high in magnesium, Apollinaris, with 130 mg/L and Gerolsteiner, with 108 mg/L. Check the labels of other mineral waters available in your region for their magnesium levels.

For most people on a low-carb or keto diet, magnesium supplementation will be enough to solve the cramps. Phinney and Volek note, however, that some people may need to supplement for up to a year to solve a significant magnesium deficiency. And some people need to supplement for life.

If regular magnesium supplementation is not eliminating your leg cramps, pay attention to the following other factors.

2. Salt

The electrolyte shifts that happen on the low-carb diet are largely the result of the loss of salt through more frequent urination. When the consumption of carbohydrates is low, the body releases less insulin, which causes the kidneys to excrete more salt in the urine.16

So, point of fact, you need more salt when you eat a low-carb ketogenic diet, as Diet Doctor has discussed in other posts.

Many people coming to the low-carb keto diet have not only heeded nutritional advice to avoid fat for years, they have also avoided salt for years. You may have to be really conscious of consuming more salt, especially on hot days or after working out. Don’t be afraid to add salt to your food and try adding a few shakes of salt to a glass of water or drink salted bone broth regularly.

Drinking pickle juice is another common recommendation to ward off leg cramps caused by salt depletion. That’s what US tennis player Francis Tiafoe did to prevent cramping recently during the blistering Australian open. While there have been more than a dozen studies on the use of pickle juice for cramp prevention published in athletic journals over the last decade, its effectiveness and impact is still under debate and investigation.17

3. Potassium may help, too

Muscle cramps, muscle twitches and rapid heartbeats can all be a symptom of low potassium, notes Franziska Spritzler, low-carb dietitian and Diet Doctor nutrition expert. In her recent guide on electrolyte supplementation she notes that when salt is lost from the body at a higher rate due to low-carb eating, potassium goes with it as the kidneys’ way to keep the sodium/potassium ratio stable.

Increasing your consumption of high potassium foods like avocado, Swiss chard and spinach can often be all that is needed to increase your potassium levels. Most people can get adequate amounts of intake solely from the food they eat.

Potassium supplements can be taken, too, but there is a risk you can take too much. Most multivitamins have about 80 mg of potassium per pill, but you can buy potassium on its own. Supplement makers by FDA regulation, however, are not allowed to make formulations with more than 99 mg of potassium per pill — that is why the pills are so tiny.18

As cardiologist Dr. Bret Scher notes, taking too much potassium can cause health issues, such as lesions in the small bowel or irregular heart rhythms. Common side effects of even small doses of potassium supplements are nausea and digestive upset.19

“Those who have altered kidney function need to be most careful with potassium supplementations and should only do so under medical guidance,” advises Dr Scher.

For the rest of us, potassium supplementation is mostly safe, but we can still get into trouble by over supplementing. Says Dr. Scher: “The best bet is to start with no more than 99 mg per day, but if you feel you need more, get a blood test to see where you are at and supplement to target a high normal level (around 4.5 mg/dl).”

When Dr. Wortman found recently that his leg cramps were coming back, he not only restarted the Phinney-Volek slow-release magnesium protocol, he chose to replace potassium in a simple, inexpensive way. He buys “lite” salt substitutes from the grocery store aisle, in which sodium chloride is mixed 50 percent with potassium chloride. A few shakes of lite salt and he gets all the extra potassium he needs.


Do you need electrolyte supplementation on a keto diet?

Guide Meat, fish, eggs, dairy, nuts and vegetables are rich in all key nutrients that your body needs on a daily basis. In some cases, however, supplementing with minerals known as electrolytes may be beneficial.

4. Dehydration or overhydration?

Some experts put dehydration as one of the top reasons people get leg cramps, especially after intense exercise, but that theory is hotly debated.20

While it is important to keep well hydrated, drinking too much water can increase salt loss and actually lead to a dangerous condition called hyponatremia — literally too little sodium. A 2016 study of hydration guidelines from exercise sites across the internet found that advice for drinking enough water during exercise to avoid muscle cramping was actually contributing to overhydration and hyponatremia.21

One simple way to check if you are well-hydrated is to note the color of your urine. If it is dark yellow, you need to drink more water. If it is extremely pale, you may be drinking too much water.  Another simple test is to pinch the skin on the back of your hand between your thumb and forefinger for about five seconds. Called the skin turgor test, when you release the pinched skin, it should rapidly go back into place. If it stays “tented up” or moves slowly back into position you are dehydrated.

Still experiencing cramps after paying attention to these four tips? Okay, now we go on to proactively identifying common triggers.

5. Situational risks factors: Common triggering ‘Ts’

The research literature shows that there are common situational triggers for leg cramps.

  • Taking diuretic medications: diuretic drugs reduce blood pressure by flushing salt out of your body, taking fluid with it. These drugs can have the side effect of causing leg cramps.22 Fortunately, the low-carb diet improves high blood pressure for many people, often enough to come off medication. If you still need to take a drug for high blood pressure, switching to another class of anti-hypertensive can help.
  • Too much sitting: A long day sitting at a desk without taking breaks to walk around, a long car ride, a long airplane flight — all of these can bring on a night-time cramp. Sitting too long, especially crossing legs, tightens calf muscles. Make sure to get up regularly to move and stretch throughout the day.
  • Too much exertion: Athletic exertion is a known trigger, but why exactly it happens to only some athletes is still debated. If you plan to be very physically active, pay extra attention to magnesium and salt supplementation, stay well hydrated with regular water or mineral water, stretch before sleep, and perhaps enjoy an Epsom salt bath after the exercise and before bed.
  • Too tight leg muscles: Tight calves and hamstring muscles are more prone to cramping. Regular yoga classes, before-bed stretching and foam rolling of legs, as demonstrated in this video, can help limber up legs and may prevent cramping. A 2012 randomized trial of nightly stretching before bed found a reduction in cramping frequency in older adults who stretched.23
  • Too much wine: Recent research in France has found that even drinking alcohol once a week can increase the risk of leg cramps almost seven times for adults over the age of 60.24 Alcohol consumption, particularly red wine, is a known anecdotal trigger for many people.
  • Travel: Perhaps because travel often entails a lot of sitting in planes or cars, unusual periods of exertion or activity, higher risks of dehydration and potentially more holiday alcohol consumption than usual, travel is a common trigger for many. Paying attention to salt intake, magnesium levels, adequate hydration and stretching may be especially key for avoiding leg cramps during times of travel.

6. Caffeine may be a trigger for some

If you are a coffee lover and all these steps above still have not reliably solved your leg cramp issue, here is one more thing to try: cut back or eliminate, for a while, your caffeine consumption. It just might help.

Coffee is a known muscle stimulant. Studies have found that it increases the contraction force of skeletal muscle.25 Over the last two decades many studies have investigated caffeine’s role in improving muscle strength, increasing endurance and enhancing performance in competitive athletes.26 A number of studies have found, however, a great deal of individual variation, likely related to genes. While some may find it improves the performance of their muscles, others can find it undermines their muscle function.27 Caffeine is also a natural diuretic and causes increased salt wasting in the kidneys and other mineral losses.28

While good studies are non-existent, a 2007 case study found that removing coffee from the diet of a 54-year-old man afflicted with nightly leg cramps completely resolved them.29

Have you suffered frequent leg cramps on the keto diet? Let us know if these tips help. What works best for you?

/ Anne Mullens


  1. BioMedical Central Family Practice 2017: Criteria in diagnosing nocturnal leg cramps: a systematic review [strong evidence]

  2. Nutrients 2015: Magnesium in prevention and therapy [overview article]

  3. Diet Doctor will not benefit from your purchases. We do not show ads, use any affiliate links, sell products or take money from industry. Instead we’re funded by the people, via our optional membership. Learn more

  4. Nutrition Review 2012: Suboptimal magnesium status in the United States: are the health consequences underestimated? [overview article]

  5. Nutrients 2018: Challenges in the diagnosis of magnesium status [overview article]

  6. Science Direct 2016: Magnesium deficiency in plants — an urgent problem [overview article]

  7. Journal of Nutritional Science Vitaminology 1990: Cooking losses of minerals in foods and its nutritional significance [weak evidence]

  8. Open Heart 2018: Subclinical magnesium deficiency: a principal driver of cardiovascular disease and a public health crisis [overview article]

  9. Nutrients 2018: Magnesium: are we consuming enough [overview article]

  10. University of Kansas School of Integrative Medicine: Magnesium: are we consuming enough

  11.  Biologic Trace Element Research 2019: Timeline (bioavailability) of magnesium compounds in hours: which magnesium compound works best? [very weak evidence]

  12. NIH Office of Supplements: Fact sheet magnesium for consumers

  13. Nutrients 2017: Myth or reality — transdermal magnesium [overview article]

  14. Nutrients 2017: Myth or reality — transdermal magnesium [overview article]

  15. Food Nutrition Research 2017: Magnesium bioavailability from mineral waters with different mineralization levels in comparison to bread and a supplement [moderate evidence]

  16. American Journal of Physiology 2007: Insulin’s impact on renal sodium transport and blood pressure in health, obesity, and diabetes [overview article]

  17. Journal of Athletic Training 2015: Plasma and electrolyte changes in exercising humans after ingestion of multiple boluses of pickle juice [weak evidence]

  18. National Institutes of Health Office of Dietary Supplements: Potassium supplement brief

  19. National Institutes of Health Office of Dietary Supplements: Potassium supplement brief

  20. Materia Socia-medica 2018: Exercise induced muscle cramps: doubts about the cause [overview article]

  21. The Physician and Sports Medicine 2016: Are we being drowned by overhydration advice on the internet? [overview article]

  22. The Journal of Clinical Hypertension 2007: Muscle cramps and diuretic therapy [overview article]

  23. Journal of Physiotherapy 2012: Stretching before sleep reduces the frequency and severity of nocturnal leg cramps in older adults: a randomised trial [weak evidence]

  24. Annals of Family Medicine 2018: Association between alcohol consumption and nocturnal leg cramps in patients over 60 years old: a case-control study [weak evidence]

  25. Journal of Physiology 1984: Caffeine potentiates low frequency skeletal muscle force in habitual and nonhabitual caffeine consumer [very weak evidence]

  26. Journal of the International Society of Sports Nutrition 2018: Effects of caffeine intake on muscle strength and power: a systematic review and meta-analysis [moderate evidence]

  27. Sports Medicine 2018: Are the current guidelines on caffeine use in sport optimal for everyone? Inter-individual variation in caffeine ergogenicity, and a move towards personalised sports nutrition [overview article]

  28. Life Sciences 1990: Effects of dietary caffeine on renal handling of minerals in adult women [very weak evidence]

  29. American Journal of Medicine 2007: Caffeine and muscle cramps: a stimulating connection [very weak evidence]