You're lying in bed. Out of nowhere: a charley horse in your calf. Painful. Confusing. You didn't do anything to cause it.
Muscle cramps are common on GLP-1s. And they usually have a simple cause.
Why GLP-1s Cause Muscle Cramps
1. Electrolyte Imbalance
This is the #1 cause. When you eat less on GLP-1s, you take in fewer electrolytes — especially sodium, potassium, and magnesium. These minerals keep your muscles working properly. When they drop, cramps happen.
2. Dehydration
GLP-1s reduce your thirst signal. You're probably drinking less water than you think you need. Dehydrated muscles cramp more easily.
3. Rapid Weight Loss
Losing weight fast changes your body's mineral balance. As fat breaks down, minerals shift. Your muscles notice.
4. Protein Deficit
If you're not eating enough protein, your muscles don't get the amino acids they need to repair and function. This can lead to cramping, especially at night.
5. Exercise Changes
Some people start exercising more when they start GLP-1s. New or increased activity = more muscle cramps, especially if you're not hydrating or eating enough to match.
What Helps
Electrolytes
This is the first thing to try. An electrolyte supplement with sodium, potassium, and magnesium can make a big difference.
What to look for:
- Sodium: 200-500mg per serving
- Potassium: 200-400mg per serving
- Magnesium: 100-200mg per serving
See our electrolyte lemonade recipe for a simple homemade option.
Magnesium Before Bed
Magnesium is the most effective single mineral for preventing nighttime leg cramps.
Best forms:
- Magnesium glycinate (gentle on the stomach)
- Magnesium citrate (also helps with constipation)
Dose: 200-400mg about 30 minutes before bed.
Stretch Before Bed
A 2-minute calf stretch before getting into bed can prevent nighttime cramps.
How:
- Stand facing a wall
- Put your hands on the wall
- Step one foot back, keep the heel on the ground
- Lean forward until you feel a stretch in your calf
- Hold 30 seconds per leg
Eat More Potassium
Potassium-rich foods help prevent cramps:
- Bananas (422mg per medium banana)
- Avocado (half an avocado = 487mg)
- Sweet potatoes (one medium = 542mg)
- Spinach (cooked, 1 cup = 839mg)
- Coconut water (1 cup = 600mg)
Drink More Water
Aim for 80+ oz daily. If you're active or it's hot, you may need more.
When to See Your Doctor
Make an appointment if:
- Cramps happen every night despite trying the fixes above
- Cramps are severe and don't improve with stretching
- You also have muscle weakness (not just cramping)
- You're on medications that affect electrolytes (diuretics, blood pressure meds)
Seek immediate care if:
- Cramps are accompanied by swelling, redness, or warmth in one leg (could be a blood clot)
- You have severe muscle pain after starting a new medication
- Your urine is dark or brown (could indicate muscle breakdown)
The Bottom Line
Muscle cramps on GLP-1s are usually caused by electrolyte imbalance, dehydration, or protein deficit. They're annoying but fixable.
Your action items:
- Start taking electrolytes daily
- Add magnesium before bed (200-400mg)
- Stretch your calves for 2 minutes before sleep
- Drink 80+ oz of water daily
- Eat potassium-rich foods when you can
- Talk to your doctor if cramps don't improve after 1-2 weeks
Most people find that electrolytes + magnesium solve the problem within a few days.
This article is for informational purposes only and does not replace medical advice. Always talk to your healthcare provider about persistent muscle cramps, especially if you take other medications.
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