Going Vegan Cold Turkey: (7 Possible Side Effects)


I know that some people transition to a vegan diet slowly, but for me it was hard to see how I could keep eating animal products once I realized how wrong it was.

So I went cold turkey, and I imagine you’re in the same boat.

For some, going vegan overnight has huge side effects, and for others there are none.

What’s clear to me now is that it depends on how much of a change your new diet is.

If you’re already used to eating lots of vegetables, fiber, and grains, your body is going to be able to process a little more of those without issue. You may even experience positive side effects right away.

But if you’re used to eating a lot of animal products, that’s where you’re likely to have some trouble.

For me, I went vegan overnight in the middle of a soccer season, fully expecting to take a hit to my fitness. Instead, I noticed virtually zero difference in how I felt (energy and fitness) because I already ate a lot of the same foods that I do now on a vegan diet.

You’ll Probably Feel Better About Yourself

happy person

Most of these side effects are negative, so let’s start off with a common positive one.

When you first start thinking about going vegan, chances are you’re not going to feel good about eating animal products all these years – feeling guilty and ashamed is common.

So when you make the plunge to go vegan, you’ll instantly feel better about who you are.

And that’s something that’s important if you’re going to stick through any difficulties with a vegan diet. Knowing that you now like who you are more is worth struggling through some temporary side effects.

Going Vegan Suddenly Can Cause Gas and Stomach Issues

gut flora

The most common negative side effects in new vegans, particularly those who make the change cold turkey is bloating and other stomach issues.

For most, a vegan diet will contain a lot more fiber than your gut is used to breaking down.

Your new diet may also contain more FODMAPs (which trigger stomach issues), and you may learn that you’re more sensitive to them than you thought.

You can read more about vegan stomach problems and remedies here.

Energy Levels of New Vegans Often Change

Some people report having less energy after going vegan, while others say they have way more. Similarly, going vegan makes some vegans feel stronger, and others weaker.

Vegans who report having less energy usually aren’t eating enough. When you make the switch, it can be hard to know what to eat, and many end up short on calories. After a few days, a severe calorie deficit will bring down energy levels.

On the other hand, people who ate a lot of junk, or had unknown bad reactions to certain animal product may start eating a lot healthier when going vegan. These people usually experience weight loss and a lot more energy just from having a better diet.

If you already ate pretty well and you track your calories for the first little bit, chances are your energy levels will stay about the same.

Going Vegan Can Lead to Better or Worse Skin (Acne)

This is very similar to the energy section above, so I won’t repeat everything.

Long story short, dairy is often a trigger for acne and other skin issues, so going vegan can clear those up pretty quickly for certain people. Same goes for related skin conditions like eczema.

On the other hand, introducing a lot of new foods gives you the chance of introducing something that your body doesn’t react well with. Typically this isn’t an issue with whole foods, but if you buy a lot of vegan specialty foods at the start for convenience it could be.

So for some, acne will get better or worse. For most others, your skin won’t change much.

Possible Joint Pain Relief

Are you a large person with joint pain?

Many NBA players struggle with joint pain because they’re so big. Several have given a vegan diet a try in the last few years, and most report that it helps with reducing inflammation, which in turn reduces joint pain.

For example, Wilson Chandler said:

“Eating a vegan diet has changed my everyday living. I sleep better, I wake up in a better mood, I recover faster, I’m not so inflamed, not so achey. I feel better overall, in everything that I do. I can take in more information easier. My mind is just open.”

Going Vegan Cold Turkey Can Lead to Cravings

This varies a lot based on the individual.

Some vegans get strong dairy and meat cravings.

It typically depends on how strongly you can link the treatment of animals to the desire of the food itself in your mind. For some this is an easier link to establish than others.

Some new vegans even experience symptoms of meat withdrawal (yes, it’s a thing). It’s not too common, but some people experience any number of the following:

  • Dizziness
  • Headaches
  • Skin rashes
  • Joint or muscle pain
  • Fatigue
  • Trouble sleeping
  • Muscle cramps

New vegans often get headaches as a result of not planning their new diet correctly.

You’ll Feel Uncomfortable (and Maybe Stressed)

Here’s the one real side effect that I did suffer: I felt very uncomfortable (i.e. lost) in general once I went vegan.

All of a sudden, a big part of your life (eating) has to completely change, and unless you did a ton of research before, you’re not sure what you’re going to be eating.

For a guy of my size and activity level, I need about 2,500-3,000 calories per day. I had no clue how to eat that much on a vegan diet when I decided to switch.

It is not a nice feeling to be concerned with if you’re going to be able to eat enough, but it’s a transition period that all vegans need to go through unless you have support from other vegans in your life.

Check out my guide to vegan foods at Whole Foods or vegan foods at Walmart to make it a little less uncomfortable.

Most Negative Side Effects of Going Vegan Will Go Away

Of the negative effects on this list, most will go away as your body gets used to the diet.

For others, you’ll learn how to get comfortable on a vegan diet and eat enough, which will clear up the other issues.

In rare cases, you might have some weird unexpected side effects not on this list, and that’s when you should make sure that you see a doctor. 

It’s not a bad idea to see a doctor anyways and get some basic blood levels checked so that you have a baseline to compare with later.

About the author

Dale Cudmore

Your friendly neighborhood vegan from Toronto. I've spent over 6 years as a freelance nutrition writer and researcher. During this time, I've tested over 50 vegan protein powders, and over 100 other types of vegan supplements.


  • Thanks Dale for your article, being a beginner vegan is really difficult to figure out what to eat when you go out.

    • You’ll get used to it!

      I was incredibly uncomfortable when I switched, but after a few months you get used to things. It helps that a lot more restaurants are offering vegan-friendly options.