Eating restrictions can sometimes put a strain on your body, which is why you may experience muscle pains or body aches during fasting.
A lack of water and certain nutrients may be behind your discomfort. Other factors — like your exercise routine — can also contribute to cramping while fasting.
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Here's a breakdown of the possible causes of fasting body aches, plus how to treat or prevent the cramps.
What Are Muscle Cramps?
Muscle cramps can occur for a number of reasons, according to the Ohio State University Wexner Medical Center, including:
- Electrolyte imbalances
- Muscle fatigue
- 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, don't exercise regularly 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 says.
Can You Get Muscle Cramps While Fasting?
"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 body aches during fasting. "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're exercising and notice pain in your legs or joint pain while fasting, "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!"
According to the Cleveland Clinic, other steps you can take to relieve fasting cramps include the following:
- Avoid caffeine
- Exercise regularly
- Stop the activity that caused the cramp
How Much Water Should You Drink?
To help you stay hydrated and avoid cramping, use this equation to determine how much water you should drink every day:
Body weight (in pounds) ÷ 2 = minimum ounces of water you should drink per day.
Preventing Cramps While Fasting
There are also steps you can take to prevent cramping while fasting (or anytime). According to the Ohio State Wexner Medical Center, these include:
- Increasing hydration
- Getting more rest
- Stretching your muscles
Getting enough electrolytes is also key to avoiding cramps. Magnesium is one major electrolyte that helps calm the muscles and is crucial for enzymatic reactions, including muscle contractions in neuromuscular signaling, which is directly associated with muscle cramping, Zarabi says.
According to the Office of Dietary Supplements, some good sources of magnesium include:
- Legumes like beans and lentils
- Nuts like almonds and cashews
- Seeds like pumpkin and chia seeds
- Whole grains like brown rice and whole-wheat bread
"Review your diet with a healthcare professional to assess adequate protein, healthy fats, complex carbs, minerals and hydration," Zarabi says. "Food is medicine and our best form of treatment, so no need to run to the pharmacy for supplements. Reevaluate your diet and ensure you have all colors of the rainbow on your plate."
Bottom line: If you're fasting, make sure you're getting enough water and electrolytes (like magnesium, potassium and calcium) to keep those pesky cramps at bay.
If fasting body aches persist, you should consider seeing a doctor to rule out any circulatory and/or neurological issues, Zarabi says. She also says that the pain could be a side effect of medications you're taking, and your doctor can help you determine if this is the case.
Is this an emergency? If you are experiencing serious medical symptoms, please see the National Library of Medicine’s list of signs you need emergency medical attention or call 911.