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CrossFit Nutrition: Zone or Paleo Diet?

What is CrossFit?

CrossFit has progressively grown in popularity since its creation by Greg Glassman back in 2000. There are now shed loads of CrossFit-affiliated gyms or “boxes” around the world.

So what is CrossFit?

It is a fitness programme that incorporates aerobic and anaerobic exercises such as gymnastics, weightlifting, rowing, running, burpees, press-ups, squats, etc. These exercises are done to time or a set number of reps. There are WODs (workout of the day) and benchmark workouts that allow you to monitor your progress.

Check out the Reebok CrossFit Games that have literally just finished this week. It’s impressive what these athletes can achieve.

CrossFit has always appealed to me because I do enjoy a challenge and variety – plus it stops you getting bored! I love CV and resistance exercise, so for me, CrossFit ticks all the boxes. I think this stems from being an ex-soldier and doing the types of exercises and always getting thrashed in PT (Physical Training) sessions!

In CrossFit, everyone is trying to improve themselves and are pushing to their limits, which I think contributes to the strong family-feel and bond between fellow CrossFitters, so I can understand why it has grown in popularity.

But what do you eat if you’re a hardcore CrossFitter or even just a dabbler?

CrossFit.com states nutrition is the foundation for performance – which I would agree with. However, they recommend having meat, veg, nuts, seeds, some fruit, a little starchy foods and no sugar. From my own experience and researching CrossFit, this nutrition recommendation is commonly translated into the Zone or Paleo diet, with many CrossFitters following these diets.

​​For both of these diets, there are slight variations quoted by different people/websites, but here is a quick overview:

The Zone diet:

Often quoted as 40:30:30 (carbs:protein:fat), although if you visit the actual website, it states:

  • 1/3 of your plate is protein
    Chicken, beef, fish, eggs, low fat dairy, Tofu and their own product Zone PastaRx
  • 2/3 is carbs and Fruit, veg and legumes (but recommends more veg than fruit intake, and to avoid ones that are high in sugar, e.g. bananas, carrots, grapes, dried fruits, sweetcorn)
  • “dash of fat”
    Nuts, nut butters, olive oil and avocado
  • Avoids grains and starchy foods such as potatoes

It also mentions about using Food Blocks, but this is quite complicated and time consuming. The diet highly promotes their own nutrition supplements… but if your diet is adequate, then it’s unlikely you need supplements, so what does that say about the diet!

On the face of it, it could sound healthy because it recommends against high sugar and fat foods. However, it could be quite restrictive, especially if it’s not well planned, such as potentially being very low in fibre and you may feel lacking in energy.

The Paleo diet:

  • Avoid cereal grains, legumes, dairy, refined sugars, potatoes, processed foods, refined vegetable oils, salt
  • Eat meat, fish, seafood, fruit, veg, eggs, nuts, seeds and “healthful oils” (olive, walnut, flax/linseed, macadamia, avocado, coconut)
  • Like the Zone diet, the Paleo diet could also risk nutritional inadequacies if not well planned, because of the imposed restrictions

The website also seems to heavily promote supplements, and even claims to “guarantee” 1 stone weight loss in a week – clearly this is unhealthy, and it promotes a fat burner supplement! The fat burner supplement states, in small writing, that it has not been evaluated by the FDA (the US Food & Drug Administration). When looking into this supplement, it appears it may not actually be safe! Avoid!

Just because a diet is common or that friends and colleagues follow it, doesn’t mean to say it is right or healthy!

​So all in all, there is no robust evidence behind either of these two diets for general health, let alone for exercise performance, so I wouldn’t recommend them.

CrossFit Foundation’s mission is to improve health and fitness, and they believe that CrossFit can help prevent deaths from chronic disease. Exercise has numerous health benefits – physically and mentally, as well as reducing risk of chronic diseases, such as heart disease and Type 2 Diabetes.

The UK Government recommends aerobic and strength exercises per week, so since CrossFit encompasses both of these types of exercise, then naturally following CrossFit would improve your health.

So what would I recommend you eat, if it’s not the Zone or Paleo?

Well, I would advise against avoiding a whole food group or specific foods, especially not starchy carbohydrates, as these will provide you with fuel and fibre (among other nutrients), and will contribute to overall health and performance.

I would recommend getting the basics right first, i.e. the Eatwell Guide, before using supplements.

Need help with your diet and unsure if you need to take supplements, then I can help you with this. Get in touch with any queries you have about supplements too.

Diet for Training

  • Trial nutrition strategies, such as types and amounts of foods and drinks that you can tolerate in the hours before the exercise
  • Match carbohydrate intake to your training needs – a Sports Dietitian can help you with this
  • Don’t forget your recovery nutrition, which can help adaptation to training and help you meet your nutrition and exercise goals

Diet for Competition

Competitions are usually over a number of days with several workouts each day. During competitions, participants are commonly unaware of the exact exercise until that day, and they don’t know the exercise duration/number of reps until they get the thumbs up by their moderator. This can make it a bit more difficult to prepare for, but here are some tips:

  • Make sure you are adequately fuelled with carbs leading up to the overall event, and before each workout
  • This may be rice/pasta/potato dishes, smoothies, fruit (fresh/tinned/dried), bagels, porridge, cereal bars – depending whether it’s in the week leading up to the event or in the hour before; depending on your individual dietary requirements, individual tolerance (that doesn’t upset your stomach), and taste preferences, etc.
  • Avoid anything too heavy between heats to make sure you “feel comfy” and don’t end up being sick/feeling nauseous!
  • In the 1-4hrs before exercise, you may wish to avoid high fat or high fibre, as this could cause some gut dramas, such as making you dash to the toilet!
  • Again, practice your nutrition strategy during training in preparation for competition – don’t trial anything new, as this could unexpectedly compromise your performance


  • Ensure you’re adequately hydrated before and after exercise – check the colour of your pee as an easy guide
  • Take on board regular sips between workouts and throughout the day to help prevent going into the next session dehydrated
  • Fluids with carbs can be helpful to replace some of your glycogen stores

Also see my blog on Hydration

Recovery Nutrition

This depends on factors such as what work you have done, the duration and intensity, and your goals – see my blog on 4 Rs of Recovery

CrossFit Nutrition: Zone or Paleo? Neither (to be blunt!)!


N.B. If you’re new to exercise, I recommend you speak with your medical doctor/physician first.

It is crucial to get your food and fluid intake right if you want to control your IBS symptoms and if you want train harder, go faster and recover quicker from training sessions and competitions. Dietary requirements are highly individualised and there’s no ‘one size fits all’ approach. Working with a Registered Clinical & Sports Dietitian to develop a bespoke plan based on your unique requirements will help to ensure the most appropriate strategy and best results are achieved. I’m here for you, so please feel free to get in touch.

The information, including but not limited to, text, graphics, images and other material contained on this website are for informational purposes only. No material on this site is intended to be a substitute for professional medical advice, examination, diagnosis, or treatment. Always seek the advice of your physician or other qualified health care provider with any questions you may have regarding a medical condition or treatment and before undertaking a new treatment or health care regimen, or before making any changes to your existing treatment, and never disregard professional medical advice or delay in seeking it because of something you have read on this website.

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