Why You Might Feel Weak on a Vegan Diet


I’ve heard quite a few stories of feeling weak on a vegan diet.

Sometimes it happens quickly after going vegan, other times it takes a while to develop.

Hell, even Anne Hathaway quit being a vegan due to feeling weak.

If you are feeling weak, I do of course suggest seeing a doctor. There could be a cause non-related to your diet that’s quite serious.

I’ll give you a summary of the most common causes of weakness that might come from being vegan, but none of it is actual medical advice.

What Causes Weakness

First ask yourself if this is a new problem that has popped up after going vegan, or if it was an existing one.

Weakness can be caused by many things that are unrelated to going vegan – coeliac disease, depression, sickness, sleep apnea, and more.

However, just like dizziness, there are some ways a vegan diet might cause weakness:

If you’re having trouble figuring out what to eat on a vegan diet and aren’t eating much, that’s an obvious cause of weakness. Go find some recipes on sites like OhSheGlows and Minimalist Baker and get cooking.

Going vegan can cause extra anxiety, worrying about eating things mistakenly or getting into arguments. Again, you’ll know if this is likely an issue or not.

But iron deficiency, that’s the most likely cause of weakness stemming from a vegan diet.

Why Anaemia is More Common in Vegans

There are a few nutrients that are harder to get from plant sources than animal sources – iron is one of the main ones.

It’s a bit harder to find in plant foods, plus the type found in plants (non-heme iron) is harder for the body to absorb.

Iron deficiency is also tricky to diagnose, since it can cause everything from weakness to fatigue or even feeling cold.

I highly recommend using Cronometer to track your diet for a few days to see if your iron intake levels are high enough.

If not, you’ll either need to start using a supplement (here are the best vegan iron supplements), or start focusing on the best vegan food sources of iron. That includes:

  • Green leafy vegetables like spinach and kale
  • Nuts and seeds
  • Beans

You Can Be Iron-Deficient Even if You’re Eating Enough

The second piece of the puzzle is that iron absorption can be limited by a few different factors (on top of already being bad in the cases of non-heme iron).

So even if you’re eating a lot, that doesn’t mean you’re necessarily absorbing much.

Here’s what you should try to do as much as possible:

  • Eat it with vitamin C – Absorbic acid (vitamin C) increases the bioavailability of non-heme iron (study source).
  • Soak your legumes – Soaking beans makes it easier to absorb iron by reducing phytate levels (which bind to minerals like iron).

The Next Thing You Should Do

As we saw above, chronic weakness can be caused by some serious diseases.

You should see a doctor to be on the safe side, and you can also check your iron levels with a simple blood test while you’re there.

About the author

Dale Cudmore

Your friendly neighborhood vegan from Toronto. Chemical engineer turned semi-professional soccer player and freelance nutrition writer. I've been vegan for years and try to make life easier for others by sharing what I've learned.

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