5 Telltale Signs You Have a Potassium Deficiency

Experts weigh in on everything you need to know about the ever-important electrolyte.


While it’s obvious that what you put in your body helps (or hurts!) your performance, there are certain things that every runner needs to make sure they’re getting enough of in their diet. One of them? Potassium.

“Potassium is an important electrolyte in your body that your cells need in order to carry out normal electrical activity, like muscle contraction or an efficient heart beat,” says Jeffrey William, M.D., a nephrologist at Beth Israel Deaconess Medical Center in Boston.

And most people don’t get enough, according to Melissa Majumdar, M.S., R.D., a spokesperson for the Academy of Nutrition and Dietetics. Based on the guidelines from the National Institutes of Health adults should get 4,700 milligrams (mg) of potassium a day, but Majumdar says that most men only get 3,000 mg and most women only get 2,300 mg. For context, 1 cup of dried apricot halves contains 1,511 mg of potassium, 1 cup of prunes contains 1,397 mg of potassium, and one medium banana contains 422 mg of potassium.

If you’re low on potassium over an extended period of time, it can mess with your cells’ ability to function normally. Not sure if you’re getting enough? While both Majumdar and William say there are no immediate symptoms of a potassium deficiency, you will start seeing signs if your deficiency becomes too severe. Here are five to look out for that might point to a consistent lack of the ever-important electrolyte—plus what you can do to boost your intake.

1. Increased Blood Pressure

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High sodium diets have been linked to high blood pressure. But potassium can help balance out the effects of sodium. In fact, the more potassium you get in your diet, the more sodium you lose through your urine, according to the American Heart Association (AHA).

If you are not taking in enough potassium, though, you may not have enough of the substance to help keep your sodium levels in check. As a result, your blood pressure may go up.

Plus, “potassium also helps to ease tension in your blood vessel walls, which helps further lower blood pressure,” the AHA says.

2. Irregular Heart Beat

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A severe potassium deficiency can lead to heart palpitations, William says. This is because the movement of potassium in and out of your body’s heart cells keeps your heartbeat in check. If there isn’t enough potassium in your heart cells, your heart won’t beat normally.

3. Muscle Cramps

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Because potassium is responsible for muscle contraction, a lack of the electrolyte extends the duration of these contractions, leading to cramps.

4. Constipation

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Digestive issues like constipation can crop up when you aren’t getting enough potassium. This is because potassium helps relay signals from your brain to various parts of your body—one being your digestive system. A lack of potassium means weak signals, which in turn slows down the whole digestive process.

5. Fatigue

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Research has shown that a lack of potassium inhibits your body’s ability to produce insulin, which leads to high blood sugar levels. After your blood sugar spikes, it will inevitably crash. That makes you feel exhausted, so you still probably won’t have enough energy to tackle your runs and other workouts. Plus, since your cells rely on potassium so much to generally function, not getting enough of it can mess with many things—energy included.

Find out if you’re potassium deficient

According to William, the only surefire way to know you have a potassium deficiency is a blood test. If you have any of the above symptoms, make an appointment with your doc to confirm your diagnosis.

How to get more potassium in your diet

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While bananas are the food that usually comes to mind when potassium is involved, dried fruit—like apricots, raisins, and prunes—kidney beans, lentils, milk, orange juice, and lima beans are also good sources of the electrolyte, according to Majumdar.


There are also supplements you can take, but Majumdar warns that since they usually only have about 80 mg, that wouldn’t really make a dent in your daily intake. However, “you can still take them to bump you up if you need it,” she says. (It’s also important to note that too much potassium can lead to kidney failure or chronic kidney disease.)

And don’t worry about losing potassium via sweat during your workout, either, says William.

“People overestimate [potassium] losses,” he says. “To lose a significant amount, you have to be training in a really hot climate, sweating liters and liters of sweat to result in a real loss.”

However, even if you are doing workouts where you sweat a normal amount, William says that if your potassium stores aren’t repleted enough over time, you can gradually lose your reserves—that’s when people “run into trouble.” This is why people sometimes drink sports drinks after a particularly sweaty workout, since they contain electrolytes—potassium included.

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