Some people report muscle pains during fasting. The cause of muscle cramps — fasting-related or otherwise — is often unclear. Human studies in this area are limited, but a few things may be going on in your body that are causing these muscle pains during fasting.
Questions you might ask yourself to start are:
- Are you getting enough water?
- Are you getting enough electrolytes, like potassium, calcium and magnesium?
- Are you exercising during fasting and at the right level, with stretching and warm-ups?
Muscle Cramps and Pain
Muscle cramps can occur for a number of reasons, according to the Ohio State University Wexner Medical Center. These include dehydration, electrolyte imbalances, muscle fatigue and loss of muscle control.
"Research does suggest inadequate stretching and muscle fatigue lead to uncontrolled contractions in the muscle," says Sharon Zarabi, RD, program director at Long Island, New York-based Northwell Health's Katz Institute for Women's Health.
"This can be caused by lack of fluids (less than 8 cups of water per day), loss of electrolytes (salts and minerals) or intense heat," Zarabi says. "Sweat from working out and warm temperatures can drain your body of water, salt, potassium, magnesium and calcium. Loss of these essential minerals and electrolytes will cause spasms."
In addition, if you overexert yourself, get out of shape, or skip out on a stretching routine, your muscles will most likely fatigue, and their neural reflex activity will be affected, Zarabi says. That lack of oxygen leads to buildup of lactic acid, which can also produce cramps, she notes.
Does Fasting Cause Muscle Cramps?
"Fasting or very low-calorie diets can cause cramping because you are depleting the muscle of minerals and electrolytes," Zarabi says.
Luckily, there are ways to address these cramps. "Cramps can be relieved through gently stretching and massaging the muscle," Zarabi says. "Hold a stretched position until the cramp stops; apply heat to tense or tight muscles, or cold to sore, tender muscles."
And if you are exercising, "always warm up and cool down before and after any physical activity," she says. "Ensure you are hydrated before and after workouts. Remember, your body is composed of 80 percent water. It is essential and you need to drink it!"
Other steps you can take to relieve muscle cramps include the following, according to the Cleveland Clinic:
- Apply heat or ice to the muscle.
- Avoid caffeine.
- Drink lots of water prior to and during exercise.
- Exercise regularly.
- Stop the activity that caused the cramp.
Preventing Muscle Cramps While Fasting
There are also steps you can take to prevent muscle cramps during fasting, or anytime, from cropping up in the first place. According to the Ohio State Wexner Medical Center, these include:
- Increasing hydration.
- Getting more rest.
- Stretching your muscles.
If muscle cramps or pain persist during fasting, you should consider seeing a doctor to rule out any circulatory and/or neurological issues, and you should also consider any medications you're taking, Zarabi says.
Zarabi points out that magnesium helps calm the muscles and is crucial for enzymatic reactions, including muscle contractions in neuromuscular signaling, which is directly associated with muscle cramping. According to the Office of Dietary Supplements, some good sources of magnesium include:
- Legumes (peanuts, black beans).
- Nuts (almonds, cashews).
- Seeds (pumpkin seeds, chia seeds).
- Whole grains (brown rice, whole wheat bread).
"Review your diet with a healthcare professional to assess adequate protein, healthy fats, complex carbs, minerals and hydration," she says. "Food is medicine and our best form of treatment, so no need to run to the pharmacy for supplements, but reevaluate your diet and ensure you have all colors of the rainbow on your plate," Zarabi says.
Bottom line: If you're fasting, make sure you are getting enough water, potassium, calcium and magnesium to keep those pesky cramps at bay, and see your doctor if they don't go away.