Carnivore Style contain affiliate links. When you click them and purchase the featured products, we may receive a commission. Learn more here.

Carnivore Diet Side Effects
What Are the Symptoms, Risks & Dangers?

Carnivore Diet Side Effects Featured Image

Someone a lot wiser than me once said that “if it was easy, they wouldn’t call it an elimination diet.”
But the reality is that, whenever you make drastic changes to your lifestyle, there will be some negative side effects.

What you need to understand and work out for yourself, is whether those downsides (most of them temporary) are worth all the benefits you can get from eating meat, and nothing but meat.

Whether you have significant weight loss goals or want to achieve some serious new lean mass, the symptoms you can encounter are very much the same.

The good news is that (a) I have encountered them all, (b) most of them fade away quickly, and (c) there are some tips and tricks that will reduce the symptoms a lot.
First, let’s take a look at what will actually happen in your body.

What Happens When You Start The All-meat Diet?

What Happens When You Start The All-meat Diet?

Most people who plan on starting the carnivore diet think that it’s simply turning the food pyramid on its head.

Basically, eat a load of meat, and then less of all the other stuff.

I was actually one of those people myself, and it came as quite an awaking that I was going to eat meat and nothing else really.

The initial reaction you might have is this must be unhealthy and full of all sorts of problems. And this is where we need to clarify a couple of things.

Yes, there are negative side effects during the phase where your body and metabolism is adapting. A lot of people call this period the “trough of despair” or just the “trough.”

It’s actually a pretty good term to describe the adaptation period you will go through.

Basically, you will encounter some flu-like symptoms (more on these below) as your body is starved of carbs.

Your blood glucose is drained, and any glycogen reserves are tapped into as well.

Once this happens, your body will actually go into a kind of panic mode.

The result is that it sends signals that are warning of starvation, and this will even happen if you’re obese and have plenty of fat reserves to tap into.

However, once your body adapts to breaking down fat storage and releasing ketones into your bloodstream, then those symptoms will reverse and completely go away.

Essentially, you encounter the very same physiological effects that people on the keto diet experience.

What frustrates me most about critics is that they jump on all these symptoms like a muddled brain and disrupted excretion to claim that “Aha, see all these side effects? That’s proof that your body is resisting and telling you to stop.”

None of those critics will have actually gone through this period, otherwise, they would know that it’s temporary.

And when you come out the other side, you will feel better and more energized than ever before.
Now, you’re probably wondering how bad those symptoms really are, right?

Symptoms Of The Adaptation Period

Symptoms Of The Adaptation Period

My personal experience from going through cyclical carnivore diet phases has resulted in the below list of main negative side effects. [1]

The first time I tried this diet was probably the worst, but I had none of the below tips at the time.
Since then I’ve gone through 4 adaptation periods, and it’s been a lot less severe since my first attempt.

Here’s what to expect:

  1. 1
     Brain fog or trouble focusing
  2. 2
    Occasional headaches often due to dehydration
  3. 3
    Mood swings as your hormones adjust
  4. 4
    Disrupted bowel movements (yes, both more and less frequent is possible)
  5. 5
    Nausea can happen if you get your meal timing wrong
  6. 6
    Digestive problems as your gallbladder adjusts
  7. 7
    Fatigue from a lack of easily accessible glucose
  8. 8
    Insomnia from restless legs and increased need to pee
  9. 9
    Dehydration through glycogen reduction
  10. 10
    Food cravings for your favorite donut or even some broccoli (NOT)

3 Major Adaptations Your Body Will Undergo

man standing on a scale

When you make a major dietary adjustment, then those come with a lot of changes in your body. This is especially the case if you’ve led a less health-conscious lifestyle.

For this diet specifically, there are 3 major things that will happen that you should be aware of.

1. Fluid Rebalancing

Before you get overly excited that you see massive weight loss in the first days to 2 weeks, a lot of this will be shedding of retained water.

As your glucose levels drop, your body will tap into glycogen reserves.

And because each gram of glycogen ties to 3 grams of water [2], you can easily lose weight from flushing out 4 to 6 pounds of water.

2. Transitioning To Fat From Sugar For Energy

While it is the default and favored method due to the easy metabolic absorption, it’s also the reason we get fat.

So, once you remove all sugar from your nutrition, fat will become the source of energy.

And if your diet doesn’t supply enough, then those love handles will be targeted. Until that process happens, you will feel like you’re drained of your usual energy.

Some of the biggest health benefits come from no longer being reliant on carbs, especially sugar, for your energy needs. 

Another benefit of no more sugar is that it has been reported to reduce the inflammation associated with arthritis [3].

It’s not something I have personal experience with, but I have heard this report from several dieters I’ve met.

3. Hormone Response And Rebalancing

One of the negative side effects of this diet is mood swings and irritability.

A lot of this stems from the fact that your hormones will fluctuate, especially Cortisol.

Because your body will initially interpret the lack of carbs as a sign of starvation, it will increase cortisol levels to try and boost blood sugar levels.

However, this hormone is also closely related to stress and anxiety.

Sudden fluctuations can make you moody, but this will pass within a few days.

Other Symptoms

Other Symptoms

The above physiological impacts can also have some mental impacts to be aware of.

Brain Changes

Most people just think of brain fog when it comes to the adaptation phase before you hit full ketosis.
While this lack of mental focus is very common and rather annoying, it’s not the only thing that will happen.

Basically, your digestive system is going to send signals to your brain saying “Hey, what are you doing? We could be starving here.”

In human history, before food became abundant, this was a very dangerous situation to be in -- so the natural brain response is stress and anxiety to signal that immediate action is needed.


If you’re anything like me and have a bit of a sweet tooth, then you could easily start noticing withdrawal-like symptoms.

This is very similar to what drug addicts experience, even if it’s not as severe.

Because sugar is such an easily accessed form of energy, your body will get very used to it as fuel, and when it suddenly disappears, it thinks that something vital is missing.


In the first few weeks, you’ll likely get regular cravings for carb-rich foods. This could be anything from a cinnamon bun to just a humble potato.

One of the main reasons for this is that your body is still struggling to get all the energy from fat.
The best solution to a carb craving is to boost your fat intake instead.

As you adapt, these cravings will subside, but you will need a bit of willpower to deal with them.

Tips And Tricks To Survive The All-meat Diet

a huge chunk of meat

So, you now know what negative side effects you can expect.

Unfortunately, there is no easy road to weight loss or muscle gain, and in many ways, you can argue that the more difficult the task might seem, the better the results will be.

But, that doesn’t mean there aren’t a few things you can do to reduce the discomforts. [4]

1. Eating More Meat

Eat More Meat

Feeling hungry in the first couple of weeks is not uncommon, and the last thing you should do is to ignore it.

You can do one of two things. Either eat more meat or eat better quality meat.

If you buy grass-fed beef, for example, you will get more and better quality nutrients from the same amount of volume, and the result will be less hunger and cravings.

Many of the carnivore diet symptoms can be tied back to low energy levels, and the best way to refuel is to increase the calories and nutrients you get from meat. 

2. Don’t Underestimate Hydration

bottle of water

I already mentioned above that in the first few days you would lose weight through glycogen reserves being a target for energy.

It’s a normal process when your dietary nutrition suddenly lacks carbs.

This process alone can remove 4 to 6 pounds of water that need to be replenished but you will also lose a load of sodium which will cause further dehydration.

At a minimum, aim for one pint of water with 3 meals a day, and 2 extra pints in between.
Believe me when I say you should keep track of your water intake in a journal.

When I first started doing this, I was surprised how little water I was actually consuming.

3. Supplements For Electrolyte Support

Supplements For Electrolyte Support

You can keep track of all the nutrition from minerals to proteins and fat, but judging your electrolyte intake can be a little more difficult.

Salt generally has a really bad name, and most people believe you should keep it to a minimum.

That’s fine when your diet is very diverse and includes many different vegetables that include just enough electrolytes to give you all you need for the day.

I generally recommend adding salt to your meals, but another option is to get a more diverse range of these essential minerals through supplements.

Simply take a few pills, and you’ll be all set with less guesswork involved.

4. Solving Digestive Problems

Digestive Problems

The digestive problems that can occur are probably the most disruptive.

Personally, I found them more difficult to live with than a couple of days of brain fog and low energy. Some people I have talked to over the years suffered from bloating and constipation.

But, the far more common issue is diarrhea. The reason for this is that your gallbladder is not producing enough bile to deal with the increased amounts of fat. Some of that will then pass through undigested.

Yes, you guessed it, this will lead to those days where you don’t want to be more than a short sprint from a toilet.

One option is to reduce fat intake, but that’s the opposite of what I suggest in the first point above.

The better solution is to take some supplements like Lipase or Betaine HCL.

You can buy these as supplements (learn more here) and take them just before eating.

5. Getting Enough Sleep

sleepy man

This is one thing a lot of people don’t focus enough on.

As you adjust how you’re dieting, especially in a carnivorous way, you can end up focusing way too much on nutritional adjustments.

But, the solution to many of the early symptoms is actually getting a really good night sleep, even with an extra hour or two in bed.

Here are some tips to follow:

  1. 1
    Sleep in a pitch dark and cool room, even open the window if possible.
  2. 2
    Turn off the lights by 11 pm.
  3. 3
    Don’t exercise before bedtime; this will increase adrenaline and testosterone which can keep you awake.
  4. 4
    No screen time after 10 pm, but reading a book is OK.
  5. 5
    Don’t drink too much after 9 pm to avoid getting up in the middle of the night.

These things will set the perfect conditions for better sleep and to help you wake up fully refreshed and ready to dig into that morning steak.

6. Stay Active And Sweat More

man working out

Being more active will obviously help with your weight loss goals, but it does a lot more than that. There are several processes in the body that are triggered by physical activity.

First of all, it will help to improve digestion by speeding it up and becoming more effective.
Secondly, exercise will increase your appetite, making you want to eat more. And more meat will mean more endurance and less brain fog.

Finally, you will sweat a lot more, and sweating is an excellent way for your body to remove toxins that may have built up through years of poor eating habits.

Moreover, decreasing toxins will reduce your risk of all sorts of disease and inflammation.

Carnivore Diet FAQs

FAQs about the side effects

Can the all-meat diet cause constipation?
Yes, the all-meat diet can cause constipation, but diarrhea is actually the more common digestive issue. Also, what many people suspect to be carnivore diet constipation is in most cases actually just fewer bowel movements.

This is because most of the meat is actually absorbed with less waste product being left over.

Can I experience digestive problems with the Carnivore diet?
Yes, you can experience digestive problems with the carnivore diet.
The most common issue is diarrhea as your body adapts to processing a lot more fat. Some supplements can help with this, and it will pass within a few weeks.

Can the carnivore diet increase cholesterol levels?
Yes, the carnivore diet can increase cholesterol levels, but it’s important to look at which types actually increase.

Some tests have shown that a meat only diet will actually lower the bad cholesterol and increase the good to end up with a much more positive ratio.

Will eating too much meat cause kidney problems?
No, eating too much unprocessed meat will not cause kidney problems. It’s generally the processed meats that are very high in preservatives like salt, and excessive amounts of salt can cause kidney issues as they struggle to flush the excess out.

However, processed meats are not recommended on the carnivore diet.

The Mayo Clinic says your cholesterol ratio is a better risk predictor than total cholesterol or LDL. To find it, you divide your total cholesterol number by your HDL score. That gives Munsey a ratio of 3.6 to 1. As 3.4 is considered optimal, he’s in a very healthy range.

Sean Hyson

Certified Strength and Conditioning Specialist


At this stage, you should have a full picture of all the carnivore diet side effects. I’ll be the first to admit that they aren’t all that pleasant, but with the above information to help identify and deal with them, my first attempt would have been so much easier. [5]

Yes, your bowel movements will change, and you will have some initial fatigue and brain fog.
But in my opinion, the benefits certainly outweigh these temporary symptoms, especially if your goal is to lose weight fast.

Don’t let them deter you and give it a try.