Ever wonder if you're actually getting enough magnesium, or if those supplements you're taking are even working? You're not alone—most people are flying blind when it comes to magnesium, either guessing at their levels or taking supplements without knowing if they need them.

Magnesium Testing, Treatment, and Safety: The Complete Guide

Magnesium deficiency affects up to 80% of people, yet most have no idea they're deficient. The problem? Standard blood tests often miss it, and the symptoms are so common (fatigue, muscle cramps, poor sleep) that we just accept them as normal life.

Skip & Fuel's Take

During my 17kg weight loss journey with 36-hour weekend fasts, magnesium became my secret weapon. Not the expensive supplements that promise everything—the right form, the right dose, at the right time. This guide cuts through the supplement industry BS and shows you exactly how to test, treat, and stay safe with magnesium.

Skip & Fuel Hack: The right magnesium form made all the difference during my fasts. No more headaches, better sleep, and way more energy. But get it wrong, and you'll feel worse than before.

How to Know If You're Actually Deficient

Here's the frustrating truth about magnesium testing: the standard blood test your doctor orders often misses deficiency. Your body keeps blood magnesium levels stable by pulling from your bones and tissues, so blood levels can look normal even when you're severely deficient.

The Tests That Actually Work

1. RBC Magnesium Test (The Gold Standard)

What it measures: Magnesium inside your red blood cells
Why it's better: Shows what's actually available to your tissues
Normal range: 4.2-6.8 mg/dL
Cost: $50-100, not always covered by insurance
Skip & Fuel tip: This is the test I wish I'd known about sooner

2. Serum Magnesium (The Standard Test)

What it measures: Magnesium floating in your blood
Why it's limited: Your body prioritizes keeping blood levels stable
Normal range: 1.7-2.2 mg/dL
Reality check: Can be "normal" even when you're deficient

3. 24-Hour Urine Test

What it measures: How much magnesium you're peeing out
Why it matters: Shows if your kidneys are holding onto magnesium
Normal range: 40-120 mg/day
Skip & Fuel tip: Low urine magnesium often means you're deficient

The Magnesium Loading Test (Most Accurate)

This is the gold standard, but it's not something you can do at home:

Get an IV infusion of magnesium
Collect your urine for 24 hours
If you retain >80%, you're deficient
If you pee out most of it, you're probably fine

The catch: It requires medical supervision and costs $200-500.

Signs You're Probably Deficient (No Test Needed)

Sometimes your body tells you everything you need to know:

Physical signs:

Muscle cramps (especially at night)
Eye twitches
Restless legs
Headaches
Fatigue that doesn't improve with sleep

Mental signs:

Anxiety or irritability
Brain fog
Poor concentration
Depression

Sleep issues:

Trouble falling asleep
Waking up frequently
Feeling unrested in the morning

Digestive issues:

Constipation
Loss of appetite
Nausea

Skip & Fuel Hack: During my first few 36-hour fasts, I had terrible headaches and muscle cramps. I thought it was just part of fasting. Turns out I was severely magnesium deficient, and the right supplement changed everything.

How to Fix Magnesium Deficiency (The Right Way)

Once you know you're deficient, here's how to actually fix it without wasting money on supplements that don't work.

Start With Food (But Don't Stop There)

The best magnesium-rich foods:

Pumpkin seeds: 1/4 cup = 190mg (48% of daily needs)
Spinach: 1 cup cooked = 157mg (39% of daily needs)
Almonds: 1/4 cup = 97mg (24% of daily needs)
Black beans: 1 cup = 120mg (30% of daily needs)
Dark chocolate: 1 oz = 64mg (16% of daily needs)
Avocado: 1 medium = 58mg (15% of daily needs)

The reality check: Even eating these foods daily, you'll probably still be deficient. Modern soil is depleted, and stress, caffeine, and alcohol all increase your needs.

Choose the Right Supplement Form

Not all magnesium supplements are created equal. Here's what actually works:

For general deficiency:

Magnesium Glycinate: 200-400mg before bed
Why it works: Highly absorbable, gentle on stomach
Skip & Fuel tip: This is what I use during my 36-hour fasts

For constipation:

Magnesium Citrate: 200-400mg on empty stomach
Why it works: Draws water into intestines
Warning: Can cause diarrhea if you take too much

For muscle pain:

Magnesium Malate: 300-600mg with meals
Why it works: Helps with energy production in muscles
Best for: Athletes and people with chronic pain

For heart health:

Magnesium Taurate: 200-400mg with meals
Why it works: Taurine helps magnesium get into heart cells
Best for: People with heart rhythm issues

Skip the cheap stuff:

Magnesium Oxide: Only 4% absorbed (waste of money)
Magnesium Carbonate: Poor absorption, mostly laxative effect

The Right Dose (This Is Where Most People Mess Up)

Start low and go slow:

Week 1: 100mg before bed
Week 2: 200mg before bed
Week 3: 300mg before bed
Week 4: 400mg before bed

How to know if it's working:

Better sleep within 3-5 days
Fewer muscle cramps within 1-2 weeks
More energy within 2-3 weeks
Less anxiety within 2-4 weeks

Red flags to watch for:

Diarrhea = too much, reduce dose
No improvement after 4 weeks = wrong form or still deficient
Worsening symptoms = possible allergy or interaction

Topical Magnesium (The Secret Weapon)

Magnesium oil spray:

How to use: 10-20 sprays on arms/legs before bed
Why it works: Bypasses digestive system, goes straight to tissues
Best for: People with sensitive stomachs or severe deficiency

Epsom salt baths:

How to use: 1-2 cups in warm bath, soak 20-30 minutes
Why it works: Magnesium absorbs through skin
Skip & Fuel tip: Perfect after a long day of fasting

Skip & Fuel Hack: I use both oral and topical magnesium during my 36-hour fasts. The oral form prevents headaches, and the topical form helps with muscle tension and sleep.

Safety First: How to Avoid Side Effects

Magnesium is generally safe, but there are some important safety considerations to keep in mind.

Common Side Effects (And How to Avoid Them)

The #1 side effect: Diarrhea

Why it happens: Too much magnesium draws water into your intestines
How to avoid: Start with 100mg and work up slowly
What to do: If you get diarrhea, reduce your dose by half
Skip & Fuel tip: Take it with food to slow absorption

Other common issues:

Nausea: Usually happens on empty stomach - take with food
Stomach cramps: Try a different form (glycinate is gentlest)
Bloating: This usually goes away after a few days

When Magnesium Can Be Dangerous

If you have kidney problems:

Why it's risky: Your kidneys can't excrete excess magnesium
What to do: Work with your doctor, start with very low doses
Warning signs: Confusion, muscle weakness, irregular heartbeat

If you're taking certain medications:

Diuretics: Can increase magnesium retention
Heart medications: May interact with magnesium
Antibiotics: Some can increase magnesium levels
What to do: Always check with your doctor first

If you're pregnant:

Why it matters: High doses can affect the baby
Safe dose: 350-400mg per day maximum
Best form: Magnesium glycinate (gentlest)
What to do: Work with your doctor

The Right Way to Take Magnesium

Timing matters:

Before bed: Best for sleep and muscle relaxation
With meals: Reduces stomach upset
Empty stomach: Only if you want faster absorption (and potential diarrhea)

Dose matters:

Start low: 100mg for first week
Go slow: Increase by 100mg each week
Stop at 400mg: Unless your doctor says otherwise
Take breaks: Consider taking weekends off

Form matters:

Magnesium glycinate: Best for most people
Magnesium citrate: Good for constipation
Magnesium malate: Good for muscle pain
Skip magnesium oxide: Poor absorption

Warning Signs to Watch For

Stop taking magnesium and call your doctor if you experience:

Severe diarrhea that doesn't stop
Muscle weakness or paralysis
Irregular heartbeat
Confusion or disorientation
Difficulty breathing
Severe nausea or vomiting

These are rare but serious:

Usually only happen with very high doses (>1000mg)
More common in people with kidney problems
Can be life-threatening if not treated

Quality Matters (Don't Buy Cheap Stuff)

Look for:

Third-party tested: USP, NSF, or ConsumerLab certified
No unnecessary additives: Avoid artificial colors, flavors
Proper labeling: Should list elemental magnesium content
Reputable brand: Do your research

Skip these:

Cheap magnesium oxide: Only 4% absorbed
Unlabeled products: No way to know what you're getting
"Miracle" products: If it sounds too good to be true, it is

Skip & Fuel Hack: I learned the hard way that cheap magnesium supplements are a waste of money. The right form and dose made all the difference during my 36-hour fasts, but it took some trial and error to find what worked.

The Bottom Line

Magnesium deficiency is more common than you think, and the standard blood test often misses it. The good news? It's usually fixable with the right approach.

Here's what you need to remember:

Get tested properly - Ask for RBC magnesium, not just serum
Start with food - But don't expect it to be enough
Choose the right form - Magnesium glycinate for most people
Start low and go slow - 100mg to start, work up to 400mg
Use both oral and topical - Double your chances of success
Watch for side effects - Diarrhea means you're taking too much
Quality matters - Don't waste money on cheap supplements

The reality check: Most people need 400-600mg of magnesium per day, but the average diet only provides 200-300mg. That's why 80% of people are deficient, even if they eat "healthy."

My personal experience: During my 17kg weight loss journey with 36-hour weekend fasts, getting my magnesium right was a game-changer. The right form and dose eliminated the headaches and muscle cramps that were making fasting miserable. It took some trial and error, but once I found what worked, everything got easier.

Ready to Try It Yourself?

This is exactly the approach I used to drop 17kg—36-hour weekend fasts (Friday 8pm to Sunday 8am), keto refueling on Sundays, and zero misery. The Skip & Fuel app will help you track it all, with electrolyte reminders and real support.

Join the waitlist to be first in line when we launch.

About the Author: Skip & Fuel was created by someone who lost 17kg in 6 months using the 36-hour weekend fasting approach. Real results, real strategies—no BS.

Magnesium Testing, Treatment, and Safety: Complete Guide