Nutrients to Watch on Keto and Carnivore (Electrolytes, Fiber and More)
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Quick answer: The nutrients most people run low on when they start keto or carnivore are the electrolytes: sodium, potassium and magnesium. Low-carb eating makes your body let go of more water and salt, especially in the first few weeks. Fiber can also drop on keto, and carnivore cuts out most plant foods. Eat a variety of real foods (including organ meats, eggs and seafood), salt your food, and ask your doctor about labs if something feels off.
A lot of what makes the first week of keto or carnivore feel rough is simply low salt and water, not the diet “failing.” Once you understand electrolytes, so much gets easier. Here’s what to watch and some simple, food-first fixes.
Why low-carb changes what you need
When you cut carbs, your insulin drops. Lower insulin tells your kidneys to let go of more sodium and water. That’s part of the quick “water weight” loss at the start. It’s also why so many people get headaches, tiredness and muscle cramps in the first week or two, the so-called keto flu (StatPearls: Ketogenic Diet).
The nutrients to watch
Sodium
Signs you’re low: headache, tiredness, dizziness when you stand up, feeling “blah.”
Try: salting your food to taste, sipping broth, and adding a pinch of salt to water when you feel off. If you have high blood pressure, heart or kidney problems, ask your doctor how much salt is right for you.
Potassium
Signs you’re low: muscle cramps, weakness, constipation.
Food sources: meat, fish (especially salmon), avocado, leafy greens and mushrooms on keto. On carnivore, fresh meat and fish are your main sources. Don’t take potassium supplements without talking with your doctor, since too much can be dangerous.
Magnesium
Signs you’re low: leg cramps at night, trouble sleeping, twitchy eyelids.
Food sources: nuts and seeds, leafy greens, avocado and dark chocolate on keto; fish and meat on carnivore. Many people use a magnesium supplement. Check with your doctor first, especially if you have kidney problems.
Fiber
On keto, fiber can drop if you cut out grains and fruit without adding low-carb vegetables. Leafy greens, broccoli, cauliflower, avocado, chia and flax help. On carnivore, there’s almost no fiber. Some people’s digestion does great without it; others struggle at first. Bathroom changes in the first few weeks are common. If they last, or you see blood, see your doctor.
Vitamin C, folate and others on carnivore
Carnivore cuts out the plants where most people get vitamin C and folate. Fresh meat, liver and other organ meats have some of these. In a survey of more than 2,000 people eating carnivore, signs of deficiency were rarely reported (Lennerz et al., 2021), but that was self-reported and short-term. If you eat carnivore long-term, ask your doctor about checking your levels.
Calcium and vitamin D
If you cut dairy (common on strict carnivore), think about where your calcium is coming from: canned fish with bones (sardines, salmon) and bone broth help. Vitamin D is low for lots of people regardless of diet, so it’s worth asking your doctor to test it.
A simple food-first checklist
- Salt your food, and drink broth when you feel off.
- Eat fatty fish or seafood a couple of times a week.
- Add liver once a week (mixed into ground beef works great if you don’t love the taste).
- Eat eggs, yolks included.
- On keto, add low-carb veggies and avocado most days.
- Drink water when you’re thirsty.
Everyone’s needs are different
Your needs depend on your size, how active you are, how much you sweat, medications (some blood pressure pills and diuretics change electrolyte levels), and your health history. That’s why basic bloodwork with your doctor is worth it, especially in the first few months.
Frequently asked questions
What deficiencies are common on keto?
Low sodium, potassium and magnesium are the most common problems, especially early on. Fiber can also be low if you don’t eat low-carb vegetables.
Do I need supplements on carnivore?
Many people do fine with salt and a variety of animal foods, including organ meats and seafood. Some add magnesium. Ask your doctor about testing before adding supplements.
How do I get electrolytes on keto without sugar?
Salt your food, sip broth, and eat potassium- and magnesium-rich foods like avocado, leafy greens, salmon and nuts. Sugar-free electrolyte mixes are another option; check the label for hidden sugar.
Why do I get leg cramps on keto?
Leg cramps are often a sign of low magnesium, potassium or sodium, especially early on. Try more salt and electrolyte-rich foods. If cramps keep happening, check with your doctor.
Your next step
Sources
- Masood W, et al. Ketogenic Diet. StatPearls. NCBI Bookshelf.
- Lennerz BS, et al. Behavioral Characteristics and Self-Reported Health Status among 2029 Adults Consuming a “Carnivore Diet”. Current Developments in Nutrition. 2021.
I’m a mom sharing my experience, not a doctor, and this isn’t medical advice. Please talk with your doctor before changing how you eat or starting supplements, especially if you take medication or have kidney, heart or blood pressure problems.
