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Alyssa Simpson RD, CDE, CLT
Alyssa Simpson

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Sibo Doctor Approved
certified gastrointestinal nutritionist
Sibo Doctor Approved
certified gastrointestinal nutritionist

Keto, Carnivore, or Intermittent Fasting? Is One Right for Me?

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Keto diet

Table of Contents

Clients often come to their appointments with a list of questions. And I love that! Asking questions means you’re willing to learn and grow — two qualities that put you on the road to success with your health goals. One of the most popular questions I get is: “should I try ‘X’ diet or eating style?”

The ‘X’ in that sentence is whatever the latest eating trend is. Clients constantly want to know if they should be eating paleo or keto or trying intermittent fasting or drinking celery juice…

I’m always skeptical of one-size-fits-all diets and eating styles. Sure, there are dietary changes that would benefit just about everyone. No one is going to become less healthy by replacing their fast food meals with wholesome real food dinners.

But we are all individuals with different lifestyles, dietary needs, imbalances, and nutrient deficiencies. And the only way to really know what foods (and supplements) will work best for you is to work with a practitioner, do some testing and find out for sure.

That being said, I do want to directly address some of the latest eating trends — and yes, you could call them “fad diets”. I get asked about these eating styles often and I want you to have a balanced picture of what these diets are + some pros and cons of each. If you’re considering following one of these eating styles, make sure and check with your practitioner to make sure it makes sense for your unique needs.

The Keto Diet

The keto diet has risen in popularity over the past few years. From a therapeutic perspective, it’s most beneficial for reducing seizures in people with epilepsy. Keto is also wildly popular as a weight-loss diet. And it can be helpful in balancing blood sugar for people who are prediabetic or diabetic.

What do you eat on keto?

The foods we eat can be divided into two general categories: micronutrients and macronutrients. Micronutrients are nutrients we need in small amounts like vitamins and minerals. Macronutrients are nutrients we need in larger amounts — protein, carbohydrates, and fats.

For decades, dietary fat was demonized. There’s a whole long story about a physiologist named Ancel Keys and how he led everyone astray by convincing them that dietary fat was the cause of heart disease. But I’ll skip that for now. Spoiler alert: his data was flawed.

More recently, studies have shown that dietary fat is an important component to health. That doesn’t mean you should run out and buy french fries or chow down on a stick of butter. I’m talking about moderate amounts of healthy fats like olive oil, coconut oil, avocados, etc.

But the keto diet takes dietary fat to a new level. Generally, keto is high in fat, moderate in protein, and very low in carbs. Typical ratios for the keto diet would be somewhere in the range of 70% to 80% of your calories coming from fats, 20% from proteins and 5% to 10% from carbohydrates.

How does the keto diet work?

Our bodies need energy. Usually, carbohydrates provide most of the energy that keeps your systems and processes humming along. But when your body doesn’t have carbohydrates to burn, it turns to fat to provide energy. And when this happens, your body goes into a state of ketosis (hence the name ‘keto’) and burns fat for energy.

So the keto diet cuts out the majority of carbohydrates, forcing your body to burn fat instead. I say “forcing” like it’s something horrible. It’s not. Being metabolically flexible — able to burn carbs or fat — is a good thing. But balance is key. Eating a diet that’s super carb-heavy, or eating a diet that virtually eliminates carbs keeps your body from being metabolically flexible.

Many people on keto try to fit about as much fat into their diets as they can. If you’ve seen keto social media influencers, you see plates filled with fatty foods. They blend their coffee with coconut or MCT oil for breakfast, eat loads of bacon, avocados, butter, fatty meats, and full-fat dairy products.

Keto Diet Pros

✔ The keto diet can be an effective way to lose weight — at least initially.

✔ Reduced carbohydrates can help improve insulin sensitivity for people with prediabetes and diabetes.

✔ Keto eliminates many carb-laden processed foods from your diet.

Keto Diet Cons

Keto can be hard to stick with.

Nearly eliminating one of the three macronutrients can be challenging. On the keto diet you eliminate sugars, starches, fruits, many condiments, alcohol, and more. It’s all-or-nothing on keto, so there are a lot of foods you just can’t eat. Sure, there are substitutes. But most people struggle to maintain this restrictive eating style for the long-term.

You might experience the “keto flu”

The good news about the keto flu is that it generally only lasts a few days. While your body is adjusting to burning fat instead of carbohydrates for energy, it’s not uncommon to develop flu-like symptoms. Common symptoms include diarrhea, constipation, poor energy, brain fog, and generally not feeling well.

Low carb diets can cause constipation

Much of the fiber you get in your diet comes from carbohydrate-rich foods. And when you give these up, it’s easy to fall short on your fiber intake. And this can cause constipation. If you struggle with digestive issues, the high fat content of the keto diet can be problematic.

Long-term side effects might include:

? Low protein levels in the blood

? Increased fat in the liver

? Kidney stones

? Micronutrient deficiencies

The Carnivore Diet

A close relative of keto, carnivore is an entirely animal-based diet. Just like the name suggests, you eat only meat and animal products. The goal is zero carbs. You eliminate all other food groups — vegetables, fruits, grains, legumes, nuts, and seeds.

People who push the carnivore diet often demonize carbs as the cause of disease. And while I agree that some carbs are genuinely unhealthy, not all carbs are equal — or bad. And if you avoid all fruits and vegetables, you are missing out on vital micronutrients and fiber that your body needs. I don’t see many substantiated benefits of this particular fad diet, so I’ll skip straight to the cons.

Carnivore Diet Cons

Extremely restrictive

You only get meat and meat products. That’s it. If you love meat, that may sound fine. But you’ll probably get sick of it. And you’ll have to turn down literally everything else.

May cause micronutrient deficiencies

Anytime you eliminate entire food groups, your body is going to miss out on the nutrients you get from them.

Can cause constipation

Carnivore is extremely low in fiber, which can result in constipation.

Can adversely affect your cholesterol

On the carnivore diet you eat a lot of saturated fat, which can elevate your LDL or bad cholesterol and increase your risk for heart disease.

Digestive issues

Protein and fat are harder for your body to digest than carbohydrates. So if you have existing digestive symptoms or IBS, the carnivore diet can make things worse.

Intermittent Fasting (IF)

We all fast — go without food for long periods of time. We do it at night while we sleep. That’s why our first meal is called breakfast. It breaks our nighttime fast.

But intermittent fasting takes this a step further. Your overnight fast is extended into your day. Basically, you cycle between periods of eating and periods of fasting.

Most intermittent fasting practices involve going without food for longer periods of time than you probably do naturally. One popular form of IF is the 16-hour fast. Within a 24-hour day, you’d go 16 straight hours without eating and then have an 8-hour window where you can eat. For example, you might stop eating at 8:00pm and then not eat your first meal the next day until lunchtime at noon.

But this isn’t the only way to incorporate IF. Some people will fast for two 24-hour periods during the week and then eat normally on the other days. There are many varieties of intermittent fasting. You can find countless books and websites detailing all the different possibilities.

Why do people use intermittent fasting?

Many people utilize this eating style as a weight-loss tool. But there are potentially some health benefits as well.

Intermittent Fasting Pros

✔ A potential weight loss solution that doesn’t involve restricting calories or whole food groups

✔ Blood sugar management — IF can improve insulin resistance and lower blood sugar

✔ May reduce inflammation

✔ May improve “bad” LDL cholesterol and blood triglycerides leading to better heart health

✔ May prevent cancer and increase life span

✔ Like the keto diet, IF can encourage your body to go into ketosis and burn fat for fuel

Intermittent Fasting Cons

? IF can be dangerous for anyone who has struggled with an eating disorder or who is underweight

? IF may not be as good for women as men. It can lead to decreased fertility and a disruption in menstrual cycles. And while it might sound nice not to have a period, an unexplained cessation of menstruation generally means there is an imbalance that is not beneficial.

? You’re going to be hungry and may experience weakness. Yes, you can get used to going longer periods without food. But IF does lead to extra hunger and any other side effects you personally experience when you go “too long” without eating.

Before you go on any fad diet…

You already know what I’m going to say. Talk to your practitioner. Again, fad diets are just that — fads. They come and go, and generally have poor long-term adherence rates. Are some beneficial for certain people or for a limited amount of time? Sure… maybe. It depends on so many factors. But some fad diets can do long-term damage or have lasting health consequences. So please, talk to your practitioner before you start one.

If you’re looking for a practitioner who can help, reach out! Let’s set up a call and talk about what steps are best for YOU when it comes to reaching your health goals, improving troublesome symptoms, or managing a condition like IBS.


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