Vegetarian to Meat Eater: How to Start, What to Expect & Side Effects

Vegetarian to Meat Eater? Here’s My Honest Advice

Quick answer: To go from vegetarian to meat eater safely, start with small portions (about 50-85 g) of easily digested meat such as fish, chicken, or broth, 2-3 times a week. Cook it simply, pair it with vegetables, and increase slowly over 2-4 weeks. Mild bloating, nausea, or constipation for 1-2 weeks is common. 

Hi everyone! This one’s for you if you’ve been a vegetarian and you’re quietly (or not so quietly) craving meat again, whether that’s for the first time in years or ever! Making the switch from vegetarian to meat eater is more common than people realize, and there’s no shame in it.

Before I get into it, I want you to know we have expert advice for reintroducing meat and animal products back into your life safely and healthily, and this month’s members’ advice is a full guide to optimum health for vegetarians. If you’re navigating this, you don’t have to figure it out alone.

Signs You Should Start Eating Meat Again

Common signs include ongoing tiredness, brain fog, low mood, strong meat cravings, cold hands and feet, or low iron or B12 on a blood test. These symptoms have many causes, so confirm with a blood test before changing your diet.

Some people find a vegetarian diet doesn’t suit them, especially when it isn’t well planned. Here is what I see most often.

Energy and mood

• Constant tiredness that doesn’t improve with rest
• Brain fog, low mood or irritability
• Strong, specific cravings for meat (not just general hunger)

Physical signs

• Cold hands and feet, dizziness or palpitations
• Hair thinning or brittle nails
• Pins and needles or poor balance (can point to low B12)

Test results

• Low ferritin (iron stores), B12, or vitamin D
• Low protein intake in a food diary

If two or three of these sound familiar, your body may be short on a nutrient. That is not a failure on your part. These signs can also come from stress, poor sleep, thyroid issues, or other conditions. Ask your doctor for a full blood count, ferritin, B12, and vitamin D before assuming it’s your diet.

Side Effects of Eating Meat After Being Vegetarian

Mild nausea, bloating, gas, constipation or looser stools, and tiredness after meals are common for the first 1-2 weeks. After a long break from meat, your digestion may need time to adjust.

This is the question I get asked most, and it doesn’t mean something is wrong with you. Your gut adapts to what you eat, so when meat comes back, you may notice:See a doctor if you have severe stomach pain, repeated vomiting, blood in your stool, or symptoms that last longer than 2-3 weeks. Speak to a professional first if you have IBD, anemia, or another digestive condition, or if you are pregnant.

It’s Okay to Want to Eat Meat Again

Here’s the thing I tell every client who comes to me feeling guilty about this: if you’re reading this, there’s a reason. Maybe your body has been quietly telling you something for months, and you’ve finally started listening. If your mind and body are asking for animal protein, that’s worth paying attention to, not fighting.

I get how loaded this decision feels. Between the ethical pressure, the identity tied up in “being vegan,” and everyone’s opinions on the internet, deciding to eat meat again can feel like admitting defeat. It isn’t. In my experience, plenty of people commit to a way of eating, discover it isn’t sustainable for their body, and then feel ashamed for wanting to change course, and that guilt alone can drag down their mood, on top of whatever nutrient gaps are already at play.

I see this play out with almost every restrictive diet, not just veganism, keto, Atkins, raw food, or low-calorie plans, all of it. There are often real ethical or cultural reasons behind the choice, but plenty of these diets simply aren’t nutritionally complete long-term, no matter how good the intentions behind them are.

Why “Plant-Based Is Healthier” Isn’t the Whole Story

You might not be thinking about long-term health impact at all right now. Maybe you went vegan for weight loss, or because a doctor flagged your cholesterol, and you feel fine in the moment. I understand that.

But here’s what I want you to know: the internet is full of claims that veganism and plant-based eating automatically lower your disease risk. That’s only true if you’re actually getting everything your body needs every single day, and in my experience, most people aren’t. Study after study links a poorly planned vegan diet to skeletal, nervous system, and immune impairments, along with anemia and depression.

The real rule, in my view, is this: any unbalanced diet, too much meat, too little of something else, or too much of anything, puts you at risk of chronic disease. This isn’t a vegan-versus-meat-eater issue. It’s an issue for everyone. Understanding how to eat for genuinely optimum health matters no matter what label you put on your diet.

Plenty of restrictive diets, including ones nobody would call “extreme,” quietly cause deficiencies that build into chronic inflammation over time. And chronic inflammation, sustained, low-grade inflammation running in the background rather than a short-term response to injury, is linked to the leading causes of death globally. Around 78% of disease-related deaths involve chronic inflammatory pathways. It also drives neuroinflammation, which shows up as anxiety, depression, brain fog, mood swings, irritability, and a decline in cognitive function.

Malnutrition Is More Common Than You’d Think

Malnutrition isn’t just an “other people, other countries” problem. It’s defined as deficiencies, imbalances, or excesses of nutrients, and it drives chronic inflammation and poor health across the board. It shows up as:

• Undernutrition
• Diet-related imbalances that feed into chronic inflammation and autoimmune conditions like obesity, diabetes, cancer, heart disease, IBD, arthritis, mental health issues, and fibromyalgia
• Inadequate micronutrient intake

The numbers back this up. According to the World Health Organization, 149 million children under five are affected by malnutrition through stunted height, 45 million are estimated to be too thin, and 38.9 million are obese. 

Globally, 1.9 billion adults are overweight or obese, and 462 million are underweight, with low- and middle-income countries carrying a disproportionate share of both obesity and malnutrition. Closer to home, the Malnutrition Task Force estimates 1.3 million people over 65 in the UK live with malnutrition.

I share these numbers because it’s easy to assume malnutrition means “not enough food.” In reality, it affects people at every income level, at every age, across every kind of diet, including ones that look perfectly healthy on the surface.

Common Vegan and Vegetarian Deficiencies

To be clear, dietary inadequacies aren’t unique to vegans and vegetarians; most people I work with, regardless of diet, need some support here. But there are a few gaps I see constantly in plant-based clients.

The type of iron you’re consuming matters enormously. Without adequate iron, your body can’t circulate oxygen properly or maintain basic homeostasis. On top of that, certain gut microbiota actually improve how well you absorb iron, and those microbiota are supported by nutrients that are hard to come by on a vegan diet alone.

In my experience, the overlooked side of veganism can genuinely put people at risk, a concern echoed in research like Bali & Naik’s 2023 study on the topic. Hundreds of studies now point to inadequate nutrient intake among vegans and vegetarians, and several essential micronutrients for optimum health come almost exclusively from animal products.

If you’re considering eating meat again after being a vegetarian, the nutrients I’d want you to keep a close eye on are B12, zinc, iodine, calcium, and PUFAs. Head over to our expert advice for vegans and vegetarians, where we cover science-backed support for things like:

• Eating meat again after being a vegetarian or a vegan
• How to eat, and what to eat (450+ recipes)
• Vegan guilt
• Worries about getting sick after reintroducing meat
• The side effects of going back to eating meat
• How to shop for anti-inflammatory groceries on a budget
• Your gut microbiome and plenty more

If you’ve been following a restricted diet for a while, or you’re dealing with malabsorption from something like inflammatory bowel disease, this anti-inflammatory diet and lifestyle approach is designed to address every nutritional concern that comes with it. The vitamins involved play essential roles throughout your life, from before you’re even born through childhood, adulthood, and into later life.

And this isn’t only relevant if you’re thinking about eating meat again. Plenty of meat-eaters assume they’re covered too, when in reality they’re just as short on essential daily vitamins. That’s exactly why nutritionists and dietitians exist; nobody gets this entirely right by instinct.

Protecting your mind and body means getting proper nutrient absorption and meeting your daily nutritional needs, and that’s what I focus on with clients through gut health, reducing inflammation, regulating the immune system, and supporting liver detox. If any of the symptoms below sound familiar, it’s worth reading 

Check out the article: Help With Anemia, B12, and Iron Deficiencies. 

Symptoms of deficiency I commonly see in vegans and vegetarians:

• Iron-deficiency anemia causes tiredness, pale skin, and weakness.
• Pernicious anemia due to poor vitamin B12 absorption.
• Fatigue and weakness that interfere with daily activities.
• Depression, anxiety, and mood swings affect emotional well-being.
• Confusion and poor coordination make it harder to think clearly.
• Headaches that range from mild discomfort to frequent migraines.
• Shortness of breath and heart palpitations during everyday activities.
• Low energy even after getting enough rest.
• Vision issues such as blurred or double vision.
• Pins and needles are caused by nerve damage and myelin sheath deterioration.
• Difficulty walking due to poor balance and muscle weakness.
• Cold hands and feet because of reduced oxygen circulation.
• Nausea, food cravings, or loss of appetite affect eating habits.
• Heart murmurs are caused by changes in blood flow.
• Unexplained weight gain linked to slowed metabolism.

Eating Meat After Being Vegetarian Side Effects

This is the question I get asked the most, so let’s address it directly: yes, there can be vegetarian eating meat again side effects, but that doesn’t mean something is wrong with you.

Your gut adapts to whatever you feed it. After months or years without meat, your stomach acid production and the specific enzymes needed to break down animal protein can become a little sluggish. So when you reintroduce meat, it’s genuinely common to notice:

• Mild nausea or a heavy feeling after eating
• Bloating or gas
• Constipation, or the opposite, looser stools for a few days
• Feeling unusually tired after a meal, as your body works harder to digest it

Will I get sick if I eat meat after being vegetarian? Usually, not in a serious way. Most of this settles within a few days to a couple of weeks as your gut recalibrates. Starting with smaller portions of easily digestible meat (think broth, poached chicken, or slow-cooked cuts) rather than diving straight into a steak makes this transition far smoother, and I’ve seen it make a real difference for clients going from vegetarian to eating meat without the digestive drama.

What About Supplements?

The recommended daily supplement intake for vegans assumes you’re already eating a balanced, nutritious diet. Supplements were never meant to replace real food. As I tell my clients constantly, supplements don’t match the bioavailability of whole food, and plenty of vegan supplement products are, ironically, full of inflammatory ingredients. If you’re thinking about eating meat again after being vegetarian, it’s worth weighing this properly rather than reaching for another supplement as a quick fix.

If you want a couple of recipes to try in the meantime, I love our Slow Cooker Indian Vegetable Curry and Carrot & Quinoa Salad.

For more on inflammatory ingredients hiding in supplements and medications, I’d recommend reading Is AG1 Supplement Good for You?, Side Effects of Antibiotics & IBD, NSAIDs, and Gut Health & Inflammation.

My Nutrition Advice If You’re Ready to Eat Meat Again

If you’re a vegetarian to meat eater, worried about your nutrition, and ready to eat meat again, I’d genuinely love to help you through it. Come join us. We’ll help you make the transition in a way that supports both your mental and physical wellness, not just one or the other.

There are plenty of vegetarian and vegan recipes here too, alongside everything else, so wherever you land, you’ll eat well and feel well.

Reintroducing meat into your diet isn’t just a change to your plate. Done properly, it protects you against chronic disease, age-related neurological decline, and anything you may be genetically predisposed to. And honestly, I don’t think you’ll be disappointed by how good the side effects feel.

If you have questions, you can book a 15-minute Zoom with me, connect with us in the forum, or dive straight in through the expert advice section.

I wish you and your family good health and real wellness, whatever that looks like for you.

Frequently Asked Questions

Q. How do I start eating meat again after being vegetarian?

Start with small portions of easily digested meat like fish or chicken, cooked simply. Eat it 2-3 times a week for the first two weeks, then increase gradually. Pair it with vegetables and water to ease digestion.

Q. Will I get sick if I eat meat after being vegetarian?

Usually not seriously. Reduced stomach acid and enzymes can cause mild nausea, bloating, or heaviness for a few days to two weeks. Smaller portions and simple cooking help. Seek medical advice for severe or persistent symptoms.

Q. Can eating meat after being vegetarian cause constipation?

Yes, temporarily. Changes in fiber intake and gut bacteria can slow digestion. Drink enough water and keep vegetables, fruit, and whole grains in your meals to help it pass.

Q. How long do side effects last?

Most digestive effects resolve in one to two weeks. If they continue beyond that, speak to your doctor or dietitian.

Q. Will I gain weight if I start eating meat?

Not because of meat itself. Weight depends on total calorie intake and activity. Lean protein in sensible portions doesn’t cause weight gain by itself.

Q. What meat should I eat first after being vegetarian?

Fish, chicken, or broth are gentle first options. They are lower in fat and easier to digest than red meat, which helps while your stomach acid and enzymes readjust. Start with about 50-85 g, cooked simply (poached, baked or slow-cooked), and leave red meat, processed meat and large portions until weeks 3-4.

Q. Do I still need supplements if I start eating meat again?

Only if a blood test shows a deficiency or your doctor advises it. Food should come first, and meat, fish, eggs and dairy can cover B12, iron and zinc for most people. Don’t take iron supplements without a test, as too much iron can be harmful, and speak to your doctor first if you are pregnant or have anemia or IBD.