Low-Carb Diets and Potassium Deficiency

As an adherent to the low-carb lifestyle (and currently on a cut) I’m acutely aware that I might not getting enough potassium: potassium is required for ketogenesis as well as supporting exercise 1. Can I get enough without eating bananas or other carbs?

Potassium is primarily found in fruit and is essential to our health. The recommended daily amount for an adult male is 4,700mg but less than 2,900mg may be lead to deficiency 2.

What good is potassium?

Potassium deficiency may cause chronic health problems like muscle cramping, weakness, fatigue, arrhythmia (irregular heartbeat) and digestive issues. A deficiency may also cause high blood pressure while a major study suggests that potassium supplements may reduce systolic blood pressure by ~8 points 3. Getting the required daily amount of potassium reduces the chance of stroke and osteoporosis.

Potassium (combined with sodium, which none of us is deficient in due to it’s over-use in prepared foods) is an electrolyte required for muscle contraction – not just in muscles like the biceps but also the heart. Potassium is required to break down carbohydrates and make amino acids from proteins therefore a deficiency of potassium will negatively effect metabolism.

Potassium is essential for ketogenesis (burning fat as energy) and flushed from the body during exercise. These two facts make it especially relevant to athletes and body builders.

How much potassium do I need?

As stated above the recommended daily amount for an adult male is 4.7g. There is no established upper limit but overdosing (called “hyperkalemia”) may be fatal which is why the FDA prohibits supplements from containing more than 99mg of potassium. It would take ~47 pills to reach just the daily requirement! However if kidneys are functioning properly and adequate water is consumed there is little fear of overdosing on potassium derived by natural sources.

There are extreme diets to treat specific ailments (diets that I do not recommend under any circumstances) in which adherents eat 30 bananas (amounting to ~15g of potassium) per day without overdose. However potassium injections would cause overdose in much smaller amounts due to the nature of synthetic potassium.

Bananas by 24oranges.nl

Photo Source: 24oranges.nl on Flickr.

Because it’s impossible for me to meet the RDA on my diet I did some research into the absolute minimum requirements for potassium. I found one pertinent value:

The Estimated Minimum Requirement for an adult male on a 2000 calorie diet is 2,000mg. 4 This amount is considered break-even because the body flushes out ~2g of potassium per day.

Meeting the potassium EMR qualifies as “barely enough” and someone on a ketogenic, low-carb diet with an active lifestyle will definitely need more to break even.

What Are the Sources of Potassium?

My research initially turned up a couple lists of so-called potassium rich foods that were too edited to be relevant to low-carb diets. These tables might be useful to tailor a diet solely around potassium but less helpful when factoring multiple dietary goals like low-carb, gluten-free, diabetes, high blood pressure or low cholesterol. Here is the first list I found:

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Source: How Stuff Works

The list above has a lot of focus on grains and fruits as the best sources of potassium – which they are. But most food contains at least a little potassium so it’s important to consider everything to get an accurate baseline. I calculated my total potassium intake using the following resources:

The food listed below represents my normal diet while cutting. I may add some fat, eat chicken instead of tuna or occasionally have a fatty protein-style burger but this is my foundation:

My Potassium Intake

From the above table it’s clear that I am falling well short of the RDA for potassium though I am exceeding the EMR of 2,000mg. I need more potassium.

Supplementing

As long as I’m dieting there’s no way for me to reach the minimum potassium requirement by food alone. I’ve been taking ~300mg of Now Foods Potassium Citrate 99 mg Capsules to get my daily intake up to 2.9g which is unlikely to cause any negative side effects. I will be increasing my supplementation to ~600mg on days that I work out in order to balance potassium losses due to exercise and I think I can do this without any worries of overdose as long as I don’t deviate significantly from my diet (i.e. eat several potatoes or bananas).

If you’re also on a calorie or food restricted diet you should make your own calculations to determine if you’re meeting the baseline potassium requirement. Then adjust your diet or talk to your doctor about supplementing.

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