Today we are going to talk about Keto and CrossFit.

In particular we will explain exactly what the ketogenic diet (keto for short) is and its history

We will detail the various types of keto diets as well as how to tell if you are in a true state of ketosis.

In addition we are going to explain where it fits in the realm of CrossFit.

This guide can get a little technical but we will break it down for the layman.

FULL DISCLOSURE: Before we start we want to state that we are NOT proponents of the keto diet. Signum’s nutrition program focuses on eating real whole foods across ALL 3 major macro groups in a balanced portion of proteins, fats AND carbs. That being said, we tried to keep this guide more informative rather than bias to our beliefs.

Let’s dive in.

The History of Keto?

There is an old quote that, “what is new was once old.” And the same can be said about keto.


The origins of the ketogenic diet (keto for short) dates back to 500 B.C.

Ancient Greeks once recommended restricting diets to treat various diseases such as epilepsy (more on that later). 

Plus fasting was also considered to be part of a healthy lifestyle.. 

Early 20th century

In the early 20th century, breakthrough research was completed on epilepsy research and diet. 

In 1911, French scientists discovered patients with epilepsy that combined fasting with low calorie diets experienced fewer seizure episodes. 

At the same time in the United States, Hugh Conklin, an American osteopathic physician, was recommending fasting to his epileptic patients.

His methods would have patients fast for 2-3 weeks at a time and he found 50% success rates for adults. Sometimes success rates were as high as 90% for children. 

Then in 1923, Dr. Russel Wilder of the Mayo Clinic found that some of his epilepsy patients experienced fewer seizure episodes as well when their blood sugar levels were lowered.

This was due to the adherence to a high-fat, low-carb diet. Dr Wilder created the original ketogenic diet to replicate the metabolism characteristics that fasting produces.

Then in 1925, Dr. Peterman, another Mayo Clinic physician, created the “classic keto” approach.

Peterman’s approach advocates 90% of calories from fat, 6% from protein and 4% from carbohydrate. (detailed below). Many keto advocates still considered this the gold standard of macronutrients in the diet.

By the late 1930’s the keto diet began to fall out of favor as a new variety of drugs became the focus of antiepileptic therapy.

Present day

By the 1990s, keto was pretty much forgotten except by those in the bodybuilding world as a form of cutting water weight going into a competition. 

But then during a 1994 Dateline episode a segment was done on a 2 year old named Charlie that suffered from epilepsy seizures until starting the keto diet. This triggered a re-emergence of the diet. 

In 1997, the film “First Do No Harm” documented Charlie’s keto experience. It starred Meryl Streep and aired on TV nation-wide.

Recently such A-list celebrities like Gwenyth Paltrow, Kim Kardashian, Mick Jagger, Halle Berry & Megan Fox have been huge proponents of the fad diet. 

We would caution people to consult with a nutrition and health expert rather than the world of social media and Hollywood before starting any new nutrition plan.

Using the Google trends tool you can see in the last 3 years the term “Keto” has really taken off.

How the Keto Diet works

How the Keto Diet Works

In a nutshell, ketosis is the human body’s backup system to fuel itself when it isn’t able to run on it’s natural fuel. The keto diet is where you power your body to run on fat, rather than carbohydrates.

Your body is made to run on glucose (sugar) as its main source of energy. The most efficient way to get glucose is in the form of carbohydrate intake. 

However, there is a backup source of energy the body can use if carbohydrate and glucose levels are too low.

The liver and body will start to break down fats into acids called ketones which simulates a fasting state. 

While in this fasted state the theory is the body will burn ketones and hence unwanted fat instead of glucose resulting in fat reduction and weight loss. 

The human body’s ability to run on fats during times of famine was once a necessary tool for survival. But due to advances in farming and crop production famine in higher GDP/capita countries is rarely a problem. (Side note: I do not believe in the Malthusian view that we will outgrow our food source. But I digress)

On top of that, the first existence of homo-sapiens is believed to be around 200,000 years ago. 

And the first evidence of crop cultivation (aka farming) occurred around 8,000B.C. 

So man has been a hunter gather (meats & fats) for about 20x longer than he/she has been farmer (veggies, fruits, starches & carbs). So the keto system is in our DNA..

We would argue that a lot has changed in the last 10,000 years since the invention of farming but I digress (again…sorry)…back to the keto diet.

How to determine if you are in a state of Ketosis

it can take up to 5 days to get into a state of ketosis.  And the only way to know if you are in a true state of ketosis requires you to test your blood, breath or urine.

Type of Keto Blood Testing

Option 1: Blood Testing

This is the most accurate way to test and measures Beta-hydroxybutyrate or BHB.

BHB levels increase in the brain, heart, liver and muscles when one is fasting or restricting calories. 

This option can also be expensive due to the investment in a blood testing tool.

And it requires a small amount of blood to be drawn in the form of a finger prick.

Option 2: Urine Testing

Urine testing measures acetoacetate, one of the three ketone bodies. But it doesn’t account for BHB. So this method may not be quite as accurate. 

However it is relatively inexpensive and you can find most testing devices in a pharmacy. 

Unlike blood testing, it is non-invasive. 

One of the cons is that as time passes, the body will produce fewer ketones in urine so accuracy is impacted. 

Option 3: Breath Testing

This is the easiest and least expensive but also the least accurate. 

A breathalizer is purchased and it reads the amount of acetone in the breath and gives readings that relate to blood ketones. 

Research is limited around this method to confirm the accuracy of breath acetone meters at higher levels.

Variations of the Keto Diet

There are 4 variations of Keto diet that have been published in medical research. Their main difference is the ratio of macros (macronutrients)

Variations of the keto diet

Classic Keto

The classic keto diet was created by Dr. Russell Wilder (detailed above) and is considered the most strict. The other 3 types are variations of classic keto.

Classic keto is a 4:1 ratio, meaning there are 4 parts of fat for every part or protein and carbs. 

Carbs have a higher calorie content than both protein and fat so it breaks down as follows:

  • 90% of one’s daily calorie intake comes from fat
  • 6% comes from protein
  • 4% come from carbohydrates

Modified Keto

Modified Keto is less restrictive and can be a good starting point or great for when tapering off classic keto. 

Its macro ratio is 3:1 to 1:1 and can also be used when adjusting for digestive issues. 

The “general” macro breakdown is as follows:

  • 82% fat
  • 12% comes from protein
  • 6% come from carbohydrates

MCT Keto

MCT is short for Medium Chain Triglyceride Keto. This version is less restrictive and popular in England and Canada but less so in the U.S.

MCT’s are able to produce ketones more easily than fat.

MCTs bypass the liver allowing it to convert into ketones.

This allows less fat and hence more carbs and proteins in the regimen. 

Coconut oil is a very common source of MCTs

IThis version carries a macro ratio of 1.9:1.

The breakdown is as follows:

  • 73% fat
  • 10% comes from protein
  • 17% come from carbohydrates

Modified Atkins (MAD)

MAD is a mix between classic Keto diet and the Atkins diet. 

The Atkins diet was created by Dr. Robert Atkins in 1972 and was popularized in the 1990s. It limits the amount of carbs but allows for as much protein as the person desires. 

However, the MAD diet discourages limitless protein consumption and encourages fat in its place. 

Its macro ratio is 1:1. But total carbs are less than 10-20 grams per day. That’s equivalent to less than 1 medium sized banana!

The calorie percentage breakdown from macronutrient is as follows:

  • 65% fat
  • 30% comes from protein
  • 5% come from carbohydrates

Why CrossFit clients may look to a keto diet

To be clear, Keto is not what we recommend at Signum CrossFit. Before you begin any nutrition program please talk to a nutrition coach near you

At Signum we follow a balanced nutrition plan where most clients will eat real whole foods with each meal consisting of 40% carbs, 30% protein and 30% fat. A much different yet still effective approach than keto.

Regardless, we find after having met with hundreds of clients, when people start with a personal trainer or a new diet they are unhappy with how they feel or look. 

So they talk to their friends, search social media and the internet. 

At some point people find the keto diet or intermittent fasting and think to themselves, “maybe this is the thing that is going to fix me.”

As a nutrition coach, it’s important to get to the deeper meaning and solve the real problem. 

Most people don’t do keto to just do it. They are trying to solve a problem. An experienced nutrition coach needs to know what his or her clients are going through in order to find a way to solve their problem.

As a nutrition coach, one needs to be careful when asked about restrictive diets

Don’t be quick to start diet bashing and really get to know what a clients wants.:

  • Does the client just want information?
  • Is the client already 2 weeks into it?
  • Do they want your confirmation of what they are about to start?
  • Or do they have a relative and/or love one that is doing it and wants to warn them?

As a nutrition coach, we need to put in the empathetic investment with our clients. This requires that we must not just jump into defensive mode and shoot the client down if they are asking us about diets that we don’t agree with. 

Keto and CrossFit and where it fits in

There are some misconceptions about what the “official” nutrition plan of CrossFit is. We will tell you it is NOT Keto. It’s not Paleo either which is what many people think.

In fact, if you attend a CrossFit Level 1 training seminar the official nutrition plan recommended by CrossFit Headquarters is the Zone Diet. 

Over the years there have been other nutrition programs that have been thought to be associated with CrossFit such as Paleo, macros (i.e. RP), etc.

But when you get down to it most of these diets/nutrition plans have spawned because an early adopter of CrossFit or a high level CrossFit athlete was/is a big proponent of it

keto and glycogen replenishment

The pic you see was taken from Guyton and Hall Textbook of Medical Physiology (page 1089) and compares the rate of glycogen replenishment using a high carb diet, a high fat & protein diet (such as keto) or no food at all. 

Summary, the study shows a high carb diet is better at restoring muscle glyogen levels and hence recovery. 

Studies (HERE) have also shown that the keto diet can have different impacts for male vs. female athletes.

Keto: the pros and cons

Pros vs cons keto


Reduced decision fatigue

One of the attractive things about keto is it’s simplicity…just eat meats and fats.

In theory it is a very simple regimen to follow which makes it attractive relative to other nutrition programs that may require calorie counting, macro counting as well as weighing and measuring food.

It can help you lose weight

Let’s face it, this is why the majority of people turn to the keto. Type “keto for weight loss” into Google and you will see over 88.6 million search results. Now type “keto for epilepsy” and there is only 1.23 million search results

The keto diet has been shown by research to impact the amount of body fat that is used for energy. Keto has also been shown to boost satiety due to the large amounts of high-fat foods that is consumed leading to less snacking during the day. 

It’s a very simple approach

One of the most appealing things about the diet is its simplicity. Basically just eat all the meats and fats. 

Unlike other nutrition plans like the zone diet (which we prescribe to at Signum) and other forms of macro counting, it just isn’t as complicated to the first timer.

It can improve brain functioning

As noted earlier, the keto diet has a higher concentration of fat macro-nutrients than other diets. 

And as we discuss in our post about macros, fats are essential to our brain and nervous system function. Hence the diet’s roots in epilepsy research.

The high percentage of fat can help reduce inflammation which can cause nerve pain in the brain. 

In addition research speculates that the diet can help with certain neurological conditions such as Parkinson’s & Alzheimer’s as well as improved concentration with children that exhibit ADHD.

Keto can help reduce inflammation

The diet can also help reduce inflammation due to reduced insulin levels. High amounts of insulin and inflammation has been connected to such chronic diseases such as type 2 diabetes, alzheimers, parkinsons, etc. 

But we caution the reader that correlation is not necessarily causation. 

When people take on a restrictive diet such as keto we find that they are also reducing the amount of high glycemic processed carbs and sugars as well.

The same takes place in other nutrition plans such as the Zone diet that promotes eating real whole foods.

So it is the elimination of high glycemic processed carbs and sugars that reduces insulin & inflammation levels and not necessarily just one diet or the other.


Long-term research as it relates to weight loss is very limited

As detailed earlier, there is a large amount of research on keto and its effects on people with epilepsy but little is known of keto’s effect on your health over time.

Keto was long forgotten until a few years ago when several Hollywood influencers touted its wonderful benefits. 

You may feel “foggy” or “not with it” at first

Recall that carbs are a major source of energy and the human brain runs exclusively on carbohydrates. 

Keto severely restricts your consumption of carbs and therefore glucose levels. 

When one first starts the keto diet, they are transitioning from using an external source of energy (glucose & carbs) to an internal source (fat & ketones).

So one may experience some temporary headaches, slower cognition episodes, as well as memory loss as the body adjusts to the new source of energy.

Initial weight loss can be mostly water weight. 

Many participants experience dramatic weight loss results at first and extract such results in a linear fashion. However, most initial weight loss has been shown to be mostly water weight from burning off glycogen levels. 

Warning: once you add back carbs & the glycogen they produce, this weight can come right back. Insert “yo-yo-ing!”

Eating unhealthy fats. 

You can’t just consume “all the fats.” True keto recommends consuming only healthy fats that come from plants and organic-based grass fed meats. 

So just ordering a double cheese burger and tossing aside the bun is not true keto.

Keto followers must always be cautious of the HDL vs. LDL cholesterol in the fats they consume. 

Now for some of the fun stuff!

Kidney stones due to a lack of fiber 

Because keto limits the amount of fruits and vegetables, a naturally occuring source of fiber, it can lead to kidney stones. 

Studies have been shown that 3%-10% of people that adhere to keto can develop kidney stones. However staying hydrated and searching out keto approved foods that have a high fiber content can be a work around. 

You may develop bad breathe 

While entering a state of ketosis, your body is breaking down acetoacetic acid which can produce a smell that is similar to acetone or nail polish. 

Digestion issues

Many have reported temporary bouts of constipation or diarrhea when starting keto.

This is because you are starting to eat more high-fat foods with a low amount of carbs and limited sources of fiber. But this can be temporary and disappear in a couple weeks. 

Exhaustion and feeling weak aka “keto flu”

Followers of keto have often cited feeling irritable, light headed, mentally slow and now with it, lethargic and constipated.

Totally understandable given that your body is made to run on carbs and glycogen stores so it must adjust. Many have found “keto flu” as temporary. But still it is not fun. 

Now we would like to hear from you! Let me know what you think of the post.

If you would like to start the conversation of your nutrition simply click the link below to schedule a Free Intro