The Keto Diet for Crosfit – Pros, Cons and How-tos

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Keto and CrossFit are two of the most popular methods people use today to get fit and healthy. 

Both are incredible tools for weight loss and improving health outcomes, like lowering your risk of heart disease and type 2 diabetes.

But there are some drawbacks to combining CrossFit and keto. Each requires an extensive commitment, which leads some to wonder if doing both simultaneously is optimal.

In this article we’ll look at pros, cons, and some instructions for getting started with keto and CrossFit.

*Be sure to consult your physician before changing your diet or starting a new workout routine. The information hereafter should be used as guidelines, not as a substitute for medical advice.

What Is the Keto Diet?

The ketogenic diet is a high-fat, moderate-protein, low-carbohydrate nutritional strategy for weight loss and health.

Keto dieters typically eat about:

  • 70 percent healthy fats
  • 20 to 25 percent protein
  • <5 to 10 percent carbohydrates

The sparse number of carbs they eat typically come from fibrous veggies like spinach, kale, asparagus, cauliflower and broccoli.

Users eat this way with the goal of reaching ketosis—a state where metabolic advantages make weight loss feel almost effortless.

What Is Ketosis?

Nutritional ketosis is a state your body enters when it’s depleted of glucose. 

The average person maintains between 100 and 400g of glucose (sugar) in their muscles at any time. This gets replenished each time we eat carbs like fruit, grains, veggies, or even sweets.

When you purposely deprive yourself of carbs long enough, your brain sends a signal to the liver to produce chemicals called ketones, or ketone bodies.

Ketones up-regulate the amount of fat your body burns instead of glucose. 

This is why so many people get great weight loss results from keto. Your body essentially turns into a fat-burning machine and uses more of its own fat for energy instead of primarily sugar.

To induce ketosis, studies show you should eat between 20 and 50g of carbohydrates per day.

It takes most people between 3 and 10 days to get into ketosis. The only true way to test this is with a home ketone monitor, but there are also anecdotal signs, such as:

  • Substantial boost in energy
  • Limited hunger
  • Metallic or sweet smelling breath

With these definitions in mind, let’s look at how one might combine a low-carb diet like keto with CrossFit.

Keto and Crossfit

CrossFit is a high-intensity functional movement fitness routine. There are definitely advantages to combining a low-carb diet with CrossFit, especially for someone who needs to lose a lot of weight.

However, it might not be a combination everyone benefits from.

Here are some pros and cons to help you make an informed decision:

Pros

Cons

  • Fatigue during workouts
  • Loss of power/strength when you first make the switch
  • Other initial adjustments to the diet 
  • Restricted food options
  • Sacrifice of lifestyle (less going out to eat, drinking, etc.)
  • Extensive meal planning/meal prep required

The key to going low-carb on CrossFit is to look at how to make it sustainable. We’ll go over two methods for this in the following sections.

Keto Diet Meal Plans

Adopting a keto meal plan might be the best way to go about doing CrossFit on a low-carb diet.

Following a meal plan ensures your body gets enough nutrients and sticks to a plan. A good keto diet meal plan will help you get the vitamins, minerals, and protein you need to workout regularly. It’ll also save you loads of time on meal prep.

Some popular companies known to the CrossFit community that offer keto meal plans include:

The major drawback to using a keto diet meal plan is simply cost. Because they’re diet specific and use high-quality ingredients, each meal works out to be between $9 and $15.

But you could also plan your own keto meals. Be sure you’re eating at least three times a day and have low-carb snacks on hand to help you adjust. 

Macros for Keto Diet

The other approach that might make CrossFit and keto work long-term is counting macronutrients.

Counting calories or macros is not required on keto, but doing so will make sure you get enough calories to fuel performance.

Because keto is mostly healthy fats and proteins, it’s actually pretty easy to undereat (which may be okay for short-term weight loss but isn’t good for long-term results).

Check out apps like MyFitnessPal or MyMacros+ to record your own macronutrients. There are free apps available, but it might be worth paying a few dollars to get features like bar scan coding to make logging food easy.

Can You Workout While Doing Keto?

You certainly can work out on keto. However, you may have to dial back the intensity as your body makes initial adjustments to ketosis.

There are a number of side effects that can occur when switching to a ketogenic diet. In fact, they are so common they have a nickname: the keto “flu.”

Symptoms include:

  • Dizziness
  • Fatigue
  • Dehydration
  • Nausea
  • Headaches
  • Cognitive “fog”
  • GI discomfort/diarrhea

Keto flu symptoms can persist for up to two weeks after making the switch. You can keep them at bay by staying hydrated and monitoring your electrolyte intake.

So basically, expect to work out only lightly the first two weeks on a keto diet. A few walks or some light barbell training may be all you can do at first. 

Definitely don’t add any other weight loss interventions (such as intermittent fasting) to the mix until your body adjusts, either.

Cyclical Keto Diet and CrossFit

If you’re happy with your weight and more focused on health and performance, a cyclical ketogenic diet (CKD) might be the better option for you.

On a cyclical ketogenic diet, athletes follow a ketogenic diet for three days at a time. 

The fourth day is a break where they eat a slightly higher number of carbs to help supplement their workouts.

This approach is especially popular for endurance athletes wanting to lose weight. Often, athletes plan their most difficult or longest workouts on their off days.

A CKD on CrossFit might look like this:

  • Follow the keto diet for three days at a time, doing perhaps one WOD and a little strength work each day.
  • Perform all your chipper/longer WODs or heavy strength workouts on the fourth day where you aren’t restricting carbs.
  • Set benchmark or PR days for your higher-carb days as well.

This loosely follows the original protocol for CorssFit.com workouts, which followed a 3 days on, 1 day off schedule.

Your cyclical diet could vary. For example, you might eat keto 5 days on, 2 days off.

The only problem is, two full days off from keto might make it harder to get back into ketosis. Eating above 50 grams of carbs reloads your muscles with glucose, so make sure you’re exercising enough to deplete yourself and justify the spike in carbs.

Targeted Ketogenic Diet

The targeted ketogenic diet (TKD) could also be useful for performance-minded CrossFitters.

On TKD, users consume their 50g of carbs for the day in a “targeted” fashion to drive results.

A TKD CrossFit diet might mean:

  • Eating the majority of your 50g of net carbs per day prior to working out.
  • Eat 30g of carbs before you workout, then 20g right after you finish to maximize the post-workout window of gains.
  • Following a standard keto diet on rest days.

This style of low-carb dieting could be especially helpful for heavy strength training.

Keto Diet and Weightlifting

Following keto as a weightlifter will look very similar to CrossFit.

The principle concern is the same: weightlifters train at a high-intensity which requires substantial amounts of fuel. Keto provides enough fuel, but not eating carbs may temporarily disrupt your workout schedule and diminish performance.

More importantly, carbohydrates consumed before exercise tends to increase performance, especially when the activities being performed are high-intensity in nature.

That’s why a CKD or TKD protocol might work best here as well.

Keep in mind, eating too much protein can actually prevent you from reaching ketosis. 

Your body undergoes a process called gluconeogenesis, where it takes amino acids (derived from dietary protein) and converts them into glucose for your muscles.

So while weightlifters commonly eat lots of protein, a keto diet weightlifter might still need to restrict intake to about 25 percent of their total calories for the day.

Popular Keto Crossfit Athletes?

There aren’t any notable CrossFit athletes who swear by the ketogenic diet.

This is because the majority of high-level CrossFitters train multiple times each day. Their bodies simply can’t perform on 50g of carbs per day or less.

However, that doesn’t mean you can’t be incredibly fit (and jacked) when following a ketogenic diet.

Tim Tebow is a huge advocate of the ketogenic diet. He lifts weights daily and played baseball for several years while following the low-carb diet. That’s proof that it’s possible if you’re willing to give your body time to adjust to it.

The Bottom Line

Keto and CrossFit could work for some people. But if you aren’t willing to really invest the time needed to make both strategies work, you may want to consider another method.

If weight loss is your top priority, there’s likely no combination more effective than CrossFit and keto. It could be a great solution for a newcomer to the sport.

If strength and performance are your top goals, you may want to look into the cyclical or targeted ketogenic diets. This way your body will at least have some carbs when you’re lifting heavy or really redlining during WODs.

About Julien

Hey! Thanks for being here. I’ve been active pretty much my whole life and I discovered Crossfit about 5 years ago. I want to help you improve your Crossfit performances by giving tips on specific movements, workouts and equipment. You have a question? Get in touch!

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