Muscle cramps, especially in the legs, are a common issue when starting a ketogenic diet. These cramps are a classic sign of the “keto flu,” a set of temporary side effects that occur as your body adapts from burning carbohydrates to burning fat for fuel. This article explores the causes of leg cramps on keto and provides practical solutions for treatment and prevention.
Introduction to Keto and Muscle Cramps
The ketogenic diet, characterized by high fat and very low carbohydrate intake, can lead to several side effects as the body adjusts. Muscle cramps, particularly in the legs, are among the most common. While the keto diet may aid weight loss and help treat certain medical conditions, it has been associated with a number of side effects - including leg cramps. These cramps are involuntary, localized muscle contractions that are often painful. Leg cramps typically affect the calf muscle, though they can occur in other parts of your leg as well. These contractions commonly occur at night and can last seconds to minutes. Most leg cramps are over in less than a few minutes.
Understanding the Causes of Muscle Cramps on Keto
Several factors can contribute to muscle cramps when following a ketogenic diet:
Electrolyte Imbalance
Electrolytes are minerals that are essential for critical functions in your body, such as cell communication. They include sodium, magnesium, chloride, potassium, calcium, phosphate, and bicarbonates. Leg cramps on a ketogenic diet are often caused by an imbalance of important minerals - often magnesium, but sometimes sodium or potassium too - along with mild dehydration. Electrolytes are positively charged minerals that play a vital role in many bodily functions, particularly those involving muscles and nerves. They’re present in fluids like blood, sweat, and urine, and they help move fluids in and out of your cells, support muscle contraction and relaxation, and assist with nerve signaling.
When you cut carbohydrates from your diet, your insulin levels naturally decrease. As your body transitions from using glucose to ketones and fats for energy, it first depletes its stores of glycogen, the stored form of glucose found in the liver and muscles. Because glycogen is bound to water, breaking it down releases that water, which is then excreted through urine. This initial loss of water explains the rapid drop in weight many people experience when starting a ketogenic or low-carbohydrate diet.
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When adapting to the keto diet, your body may lose more electrolytes through urination in response to decreased levels of blood sugar and the hormone insulin. This loss is typically greatest during the first 1-4 days of transitioning to keto, so muscle cramps related to electrolyte imbalance may be worse during this period. If your levels become depleted, your nerve cells may become more sensitive. In turn, this leads to pressure on nerve endings, which may cause muscle spasms.
Dehydration
People transitioning to the keto diet often urinate more due to factors like reduced insulin levels and increased sodium excretion. In turn, increased urination can lead to dehydration, another potential cause of leg cramps. Dehydration is one of the most common keto side effects and may thus increase your risk of leg cramps. Sweating results in the loss of both water and electrolytes, which is why electrolyte replacement is emphasized during and after physical activity.
Other Potential Causes
Several other factors may also cause leg cramps. For example, certain medications, such as diuretics, asthma drugs, and statins, are associated with an increased risk of these pains. Additionally, sedentary habits, old age, strenuous physical activity, and medical conditions like liver and kidney failure are associated with leg cramps.
Practical Tips to Prevent and Treat Muscle Cramps
The best way to prevent and treat leg cramps on keto is to ensure that you’re eating nutritious foods, supplementing if necessary, and staying properly hydrated. Here are a few tips:
Maintain Proper Hydration
One of the simplest and most effective ways to support hydration is to drink water consistently throughout the day. A general guideline is to consume at least half your body weight in ounces of water daily. For instance, if you weigh 150 pounds, aim for around 75 ounces (2.6 liters) of water. If you’re physically active while following a ketogenic diet, it’s especially important to hydrate before, during, and after your workouts.
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Replenish Electrolytes Through Diet
To support healthy electrolyte levels, focus on incorporating these foods into your diet:
- Potassium-rich foods: Avocados, Swiss chard, spinach, onions, tomatoes, beet greens, and mushrooms are keto-friendly, potassium-rich foods that can help rebalance your electrolyte levels. Potassium plays a vital role in cellular energy balance by supporting fluid regulation and the transport of nutrients and waste across cell membranes. It also works alongside sodium, calcium, and magnesium to coordinate muscle contraction and relaxation. Leafy greens such as beet greens, Swiss chard, and spinach are excellent sources, as are vegetables like mushrooms, Brussels sprouts, zucchini, broccoli, and asparagus.
- Magnesium-rich foods: Pumpkin seeds, Brazil nuts, cashews, kale, arugula, broccoli, and oysters are low in carbs and high in magnesium to aid your electrolytes. Magnesium is the fourth most abundant mineral in the body and is essential for health, yet many people are deficient - even those following a nutrient-dense, ketogenic diet. Magnesium and calcium work together to regulate muscle and nerve activity. While calcium stimulates muscle contraction, magnesium promotes relaxation. Leafy greens such as spinach and Swiss chard are excellent sources, as are avocados, hemp seeds, chia seeds, and pumpkin seeds.
- Sodium: To help maintain sodium balance on a keto diet - especially during the keto adaptation phase - consider adding a pinch of Himalayan or sea salt to your meals or water throughout the day. These unrefined salts provide sodium along with lesser amounts of trace minerals. Sodium plays a critical role in maintaining fluid balance both inside and outside of cells and serves as a cofactor in muscle contraction and nerve function. It also helps regulate the balance of other key electrolytes, including potassium and magnesium.
Consider Electrolyte Supplements
Taking a magnesium, potassium, or multi-mineral supplement may be a good idea for those transitioning to a keto diet. Adding mineral drops to your water is a convenient option; these typically contain concentrated trace elements that support electrolyte balance. Keto-friendly electrolyte powders can also be useful, particularly after exercise or periods of heavy sweating. These are typically free of added sugars and can be mixed into water or smoothies.
Other Helpful Tips
- Consume Enough Salt: Salt your food and consider sipping on salted bone broth to reduce the chances of electrolyte imbalance.
- Cut Back on or Avoid Alcohol: Alcohol is a diuretic and may worsen dehydration. Some research suggests that alcohol use may be related to leg cramps.
- Engage in Gentle Exercise: Try walking, stretching, and yoga when first adapting to keto. Avoid intense exercise for the first few days to reduce the chance of leg cramps.
- Avoid Prolonged Sitting: Prolonged sitting is associated with various health concerns, including increased risk of muscle cramps. If you spend much of your day at a desk, make it a point to stand up, stretch, and move your body regularly. Setting a reminder to walk or gently stretch every couple of hours can help promote circulation and reduce muscle tension.
Addressing Sore Muscles on Keto
No one is quite sure of the causes of keto leg pain. In general, most people feel run down during the first few days of the keto diet because their bodies are trying to adapt to the huge dietary change. Your body likes to maintain homeostasis, or a state of balance. Suddenly taking away carbs, its preferred source of energy, can throw your body into a tailspin. Now the body has to search for another means of providing energy, burning fat, and creating ketones, in a metabolic process known as ketosis.
The effects of ketones on the body aren't well understood. In people with diabetes, a buildup of ketones in the blood causes a dangerous condition called ketoacidosis, which can have side effects including fatigue, nausea, weakness, shortness of breath, and a fruity odor to the breath, according to Mayo Clinic.
This is not the same as ketosis, which is a natural process that raises ketone levels but not nearly as high as in ketoacidosis; however, ketones may be responsible for some of the uncomfortable side effects you experience.
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In addition, when you drastically reduce your carbs, you lose a lot of water weight in the first few days. In fact, most of the weight loss you'll see at the beginning of a diet is water loss. If you're not adequately replacing these fluids, you risk dehydration, primary symptoms of which include muscle cramps, according to MedlinePlus.
If you're also exercising during this time, you risk even more fluid loss through sweat. Doing vigorous activities such as running or interval training while dehydrated can make matters worse. Putting stress on muscles that are already fatigued from lack of carbs and fluids will likely result in greater muscle damage and soreness after your workout.
Lastly, losing fluids and cutting carbs can lead to losses of important electrolyte minerals, including magnesium, potassium, calcium, and sodium.
Managing Other Keto Side Effects
Aside from leg cramps, other symptoms associated with the keto diet include headaches, constipation, and fatigue - collectively known as the keto flu. These symptoms may likewise be caused or worsened by dehydration and electrolyte imbalances, making prevention all the more important.
Loss of Salts
There are some changes with fluid balance that can typically occur within the first couple of weeks of a ketogenic diet. This happens as the body uses up its stored sugar (glycogen) which releases water into the blood that gets passed out of the body through urine. As fluid is passed out of the body, salts in the body can get depleted too. As a result, you may experience a loss of fluid and salts as you move into and maintain ketosis.
Make sure you keep yourself hydrated through the day. Water is the best drink for hydration but tea and coffee are also fine as long as they’re not very milky. Ensure you have enough salt as this can prevent side effects such as headaches and wooziness. You are free to add sea salt to your food and can take salts by drinking vegetable or bone broths and bouillons too. Potassium and magnesium are other important salts. As long as you are eating healthy, natural foods (such as nuts, meat, fish, dairy and a range of vegetables), you shouldn’t have a problem getting enough magnesium and potassium.
Keto-Flu
The first few weeks of transitioning to a ketogenic diet can be challenging for some people. Whereas others adapt to it more easily. Your body may be used to relying mainly on glucose for energy and so it will need to switch to using ketones for fuel. This adaptation process is known as keto-adaption. Keto-adaption may result in some initial ‘brain fog’, but this will disappear once the body has fully adapted and some people feel sharper at this point. It is estimated that keto-adaption takes around four weeks on average but the side effects themselves often disappear sooner.
During that time, and especially at the end of the first week, it is likely that you may feel some symptoms that are similar to the flu, such as:
- Brain fog / slow thinking
- Dizziness
- Fatigue
- Racing heart rate when lying down
- Insomnia
- Cravings
You may find that allowing your body to ease into ketosis helps to lessen the effect of side effects. This can be done by gradually lowering carbohydrate intake over a few weeks. Whether you jump directly into a ketogenic diet or go gradually, remember the first point about having fluid and salts as this will help prevent you feeling lousy.
Changes in Bowel Habits
Changing to a ketogenic diet may bring about changes in bowel habits such as constipation. This is often the case with any major change in diet as the body’s own gut bacteria will need to adapt to handle different foods in different amounts. Bowel habits should usually improve within a couple of weeks. If they don’t, it could be that you’re not getting enough fibre. Drink plenty of water and consider increasing your consumption of non-starchy, fibrous vegetable, legumes, nuts and seeds, as these are all good low-carbohydrate sources of fibre.
Bad Breath
Bad breath , sometimes referred to as keto-breath, can sometimes occur as you enter the fat-burning state of ketosis. Ketones can be released in the breath, as well as in the urine and sweat. Acetone is a form of ketone that when released on the breath may lead to a metallic taste in the mouth or a less-than-pleasant smelling breath. This is usually temporary and will likely disappear after a few weeks without having to come out of ketosis by reintroducing carbs. If bad breath is a problem, minty sugar-free gum or breath freshener can help mask the smell. Another solution is to consider extra rigorous oral hygiene by brushing teeth and using mouthwash more frequently through the day.
Lack of Energy
One of the biggest misconceptions about ketogenic diets is that a lack of glucose depletes the body of energy. Maintaining steady energy levels is actually more challenging on a standard diet as it varies according to fluctuations in blood sugar , which is dependent upon the insulin response to carbohydrate intake. Eating a lower amount of carbohydrates on a ketogenic diet does not prevents the roller-coaster of sugar levels. Once in ketosis, the body can draw energy from its own fat stores and the liver is able to create as much glucose as the body needs -and not too much. As a result, by cutting out carbs, the body finds it easier to regulate sugar levels and energy. Whilst you may notice a dip in energy initially during the adaptation phase, this should pass within a few weeks.
When to Seek Professional Help
If you have persistent or extreme leg cramps, you should visit a health professional to ensure that you’re not experiencing symptoms of a more serious medical condition. If muscle spasms persist despite lifestyle adjustments, underlying conditions such as mineral absorption issues, thyroid dysfunction, or neurological problems may be involved. At Mirabile M.D., we offer comprehensive testing and personalized treatment plans to address these issues and optimize your health while on keto. Blood tests measuring CRP, ESR, hormone panels can help identify underlying inflammation and imbalances.