The Most Common Mistakes CrossFit Athletes Make When It Comes to Nutrition

When choosing between various healthy eating plans or performance-driven nutrition programs, your success might be determined more by your overall approach to the role of food in achieving your goals than the exact food you eat.

Are any of these common nutrition misconceptions CrossFit athletes have affecting your progress?


Many athletes believe they have to be perfect all the time to see progress, says Dr Mike Molly, founder of M2 Performance Nutrition and coach to over 40 CrossFit Games athletes such as Sara Sigmundsdottir, Chyna Cho and Zack George.

“This applies a lot of unintended pressure to them, especially within the CrossFit community, where people are so demanding of themselves and have such high expectations,” he says.

“Instead, recognize that six days a week would be amazing; that’s about 85% compliance. If you can do that, you’re well on your way to making long term progress, and it’s a sustainable approach as well.”


“The biggest issue people have, in general, is choosing nutrition programs that aren’t sustainable for them in the long term,” says Dr Molloy.

If athletes aren’t happy with their diets because they restrict their calories too much or simply because they like sugar every once in a while, the inevitable result is that they’ll give up and stop said diet – with consequences such as old habits or bad relationships with food coming back to them.

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“If you can give somebody something that’s a little bit more sustainable, where progress is a little bit slower, it actually tends to work better in the long term,” says Dr Molloy. “The faster result isn’t always the better result when it comes to nutrition.”


When you do anaerobic exercise, your muscles are fully dependent on glucose to provide the energy required. If you eat a low carb diet, you won’t have the fuel to perform anaerobically.

Every athlete needs energy to perform. The ability to walk, run, lift weights and, on a more basic level, sustain every bodily function, depends on one’s ability to extract energy from the food we consume.

Current research still points to carbohydrate as an indispensable energy source for high-intensity performance, concluded a 2017 study looking into high-quality carbohydrates and physical performance.

Undereating and living in a large calorie deficit can be a big problem in CrossFit athletes, and this not only leads to fatigue and mental exhaustion but will also hinder your performance.


There is no such thing as “bad food,” just micronutrient dense, unprocessed food that’s good for our health and for our performance, and flavourful, macronutrient dense foods like donuts and ice cream which can be good for emotional health – and maybe your mental health – to have every once in a while.

“People take the labels that they apply to certain foods and then they start to apply it to themselves for eating them,” says Dr Molloy. “So no longer is the ice cream bad, no longer is the donut bad, but I’m a bad person for having eaten that thing. And at the end of the day, you can start to separate those things and say there is no such thing as a good and bad food, there’s just food and it has different purposes.”

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Fully restricting whole food groups can have big psychological consequences, the simplest being that, by asking someone to completely avoid something in their diet, you’ll make them crave it more, especially because these are usually foods people enjoy eating.

“It comes down to sustainability,” explains Dr Molloy. “If I cut all of those things in your diet, will you make progress in the short term? Probably. But are you likely to make it work for longer than 30 or 60 days? Probably not.”

“When you remove this restrictive label: ‘I can’t have that,’ then it no longer holds the power over you,” he concludes. A more flexible approach allows for sustainability in a way that an ultra-strict diet does not.


When you first learn about CrossFit, you learn its definition of fitness:

“Eat meat and vegetables, nuts and seeds, some fruit, little starch and no sugar. Keep intake to levels that will support exercise but not body fat.”

CrossFit, as an institution, has always advocated for a heathy diet and used to encourage athletes to follow the zone diet, with the community subsequently fervently adopting the paleo diet.

The zone and paleo diets might work very well for some people, but these approaches won’t be perfect for everyone.

“Our nutritional needs are all a little bit different,” says Dr Molloy. “You can take people and say ‘everybody should eat protein, fat and carbohydrates, and if they do these things, then they’ll optimize their performance and body composition.’ But that totally removes the emotional aspects from food.”

Even for athletes training around the same intensity, at relatively the same height and weight, a nutritional plan might look completely different because one has to account for their lifestyle and personal situation.

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“Paleo is great for a lot of people, but if you come from a place where you have any eating-disorder-type background at all, telling somebody: ‘hey, you can’t eat bread, you can’t eat rice, you can’t eat oatmeal, no dairy,’ that can trigger some pretty serious emotions,” says Dr Molloy.

“Why not use somebody’s personal history to design a nutrition approach that’s better for them, instead of shoving them into a model? Take instead a general approach and try to fit what you do to how you live your life.”


  • Try to consume around 1.6 to 2.2 grams of protein per kilogram of bodyweight per day. Working around this frame has been proven to support lean muscle mass generation. Protein also has a good thermic effect, which means it requires a little bit of energy to break down into your body, as well as having good satiety levels, making us feel full.
  • Vary the amount of fat and carbohydrate you consume based upon how much training you are doing. Someone working out three times a week for an hour might not need as so many carbohydrates, but if you’re training for two hours a day, five or six days a week, you’ll want to eat more.
  • The amount of training you do influences the quality of your food. An athlete training three times a week for an hour each time should generally consume most of their carbohydrates exclusively from unprocessed sources; foods like fruits and vegetables and roots. Whereas an athlete who trains two hours a day or more, while they should still consume micronutrient-rich fruits and vegetables, their diet should also include denser carbohydrate sources such as rice, oats and whole wheats to allow them to eat all their macronutrients.

“Take Sara Sigmundsdottir for example,” says Dr Molloy. “She can eat anywhere between 3,000 and 3,500 calories a day, depending upon which part of her season she’s in. Asking Sarah to eat 3,500 calories using only broccoli and sweet potatoes, she’s going to go crazy at some point because she’s going to be so full.

“But if she can eat white rice and oatmeal – all these things that are calorically dense – then she can actually fill her macros.

“But for your average gym goer who’s working out four days a week for an hour a day, they don’t need that. They can get all of their macronutrient requirements down just using whole, unprocessed foods.”

You can find out more about Dr Mike Molloy and his methods at M2 Performance Nutrition.

All content within this article is provided for general information only and should not be treated as a substitute for the medical advice of your own doctor or any other health care professional.

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