If you’re looking for a weight loss plan, or a new fad diet, stop reading now. This article is going to be a comprehensive guide to eating like an athlete, as well as an introduction to the principles that underline eating for performance.  By the end of the article, you will be able to set up your own customized nutrition plan, as well as understand what you need to eat for maximum performance.

The first thing we need to understand when we are discussing nutrition, is that there are some well established guidelines, but very few absolute rules.  You do need to eat food, or you will die.  That’s a hard and fast rule, but beyond that, it depends on a myriad of variables: your goals, sex, age, activity level, genetics etc.  If you feel like you already have a good grounding on the basics you can skip down a few paragraphs to figuring out your custom nutrition plan. It’s about to get sciency.

Scientific Principles of Nutrition 

Before we get into the nitty gritty of setting up our plans, we need to first get on the same page in terms of understanding the scientific principles of nutrition, and how they apply to crossfitters.

The Calorie

The calorie is a unit of energy.  The calories we use for food counting are actually kilocalories, i.e made up of one thousand calories (1Kcal), but like most folks we will just say one calorie (cal) to mean what we commonly see on nutrition labels.

Nerd tip, it is also defined as the amount of energy needed to raise one gram of water one degree centigrade.  Therefore 1 Kcal is the amount of energy needed to raise one kilogram of water one degree centigrade.


There are three primary macro nutrients: protein, carbohydrates, and fat.  Please just flush most of what you think about each of these down the toilet.  Due to thousands of fad diets, each of these macro’s has their own group of myths and lies attached to each.  Suffice it to say, that a hard training athlete needs all three.


Protein is the primary structural, and functional component of each cell in your body.  They are used to repair cells, create enzymes, and create hormones, as well as many other uses.  Regardless of what Thunder says down at the Golds, protein does not only build muscle tissue.

They are composed of amino acids, which are nitrogenous compounds that are bound together with peptides to form protein molecules.  While these compounds are used in nearly every part of the body, for sports performance, proteins and amino acids are used for building and repairing muscle mass and other structures in the body.


Carbs are a great source of energy in your body, but technically they are not necessary for survival.  They are; however, necessary for a crossfitter.

There are three types of carbohydrates.

  • Monosaccharides (glucose, fructose, galactose)
  • Disaccharides (sucrose, lactose, and maltose)
  • Polysaccharides (complex carbs).

Monosaccharides are made of single sugar molecules.  In the body, glucose is circulated in your blood as a primary energy source.

Table sugar (sucrose) is the most common type of disaccharide.  Sucrose occurs naturally in most fruits and is part of a balanced diet.

Polysaccharides are the most complex carb.  They are things like fiber, starch, and glycogen.   Glycogen, as you will see, is incredibly important for sports performance, and is the primary molecule that allows athletes to produce high power outputs.

Glycogen is stored both in your liver, and in your muscle cells.  When you exercise, glycogen is converted into adenosine triphosphate (ATP), which is the actual chemical that powers your cells.  Because it can convert quickly and efficiently to ATP, it is a primary energy source for high power output activities.  Basically, anything above a brisk walk will require glycogen.

If you like this kind of nerd fitness info, drop your email in on the right to get the latest articles sent straight to you.  If you don’t, I’ll assume you’re President of the One Direction Fan Club.


Fats are a type of lipid that is very energy dense in our bodies.  They are present in multiple forms: triglycerides, fatty acids, and cholesterol.  For the athlete, fats are used to produce hormones and other substances that are critical to your performance.

Most folks have a very low opinion of fat because of years of garbage fad diets. People still continue to have a poor idea of cholesterol as well.  This molecule is critical for the production of vitamin D, testosterone, as well as other essential functions.

Your liver also produces cholesterol if you do not eat sufficient amounts of it.  Unless you have a diagnosed medical condition you need to be consuming cholesterol.

Vitamins and Minerals 

These are also referred to as micronutrients.  You need to think of them as enablers to the primary functions of your body.  In many chemical reactions that your body completes, just to keep you alive, vitamins are necessary facilitators to maintain proper function.

Most folks are deficient in some vitamins or minerals which is generally not a huge issue as the body can produce some of these, but if you are deficient in calcium well you’ve got osteoporosis, and if you are deficient in iron, well good luck trying to transport oxygen into your bloodstream.  Most of these deficiencies can be taken care of by eating a diverse diet and taking a multivitamin regularly.


These are sodium chloride and potassium.  They are critical to normal muscular function and hydration.  The body uses these chemicals to transport substances into and out of cells.  If you are deficient, you will become dehydrated, and at best limit your performance.  You can also severely cramp, and end up in the hospital if these compounds are too far out of wack.

Make sure that you aren’t avoiding salt, which is sodium chloride, and you will probably be fine as these chemicals are present in a wide variety of foods.

We’ve now covered the big picture stuff that will affect our performance as a crossfit athletes.  I know it’s been pretty rough; there were science words in there and everything, but stick with us because now we are going to get into the fun stuff.

If you’d like to learn more about the science behind nutrition and sports performance, check out the book The Essentials of Strength Training and Conditioning.  A lot of the background info for this article comes from there, and it a very comprehensive book.  I use the 4th edition, but the third edition is hella cheap now. Both links are (Amazon Affiliate Links).

Nutrition for Crossfit Performance 

This is where we need to talk about some variables that are going to have a big impact on your customized nutrition plan.  This is also where you need to be honest with yourself and not fudge your numbers.

Variables That Affect Crossfit 

First you need to decide what your goal is in crossfit.  If you are recreationally fit, and just like the gym and the atmosphere, then you will need to eat that way.  If you are a Regionals hopeful, then you will be eating entirely differently.

Resting Metabolic Rate

The first thing you will need to figure out is your resting metabolic rate or RMR.  This is the amount of energy your body uses for normal baseline functions; think laying in bed watching my little pony all day.  Check this calculator out to figure your RMR.

The next step will be to determine how many calories you burn in addition to the RMR.  If you have a very active job (mechanic, waiter, farmer) then you will need to add in additional calories to cover this energy expenditure.

If you are very active during the day, you might be burning up to 800-1000cal above your RMR, but in my experience it’s generally something like 500cal above your RMR.  This is something that you will have to play with to get right though.

Macros and Calories 

Now that we know what you are burning for normal daily activity, we can begin to tackle what you need to support your workouts.  This means that we should be at, or a little above our daily calorie burn. Lets work through an example so you can see how this works.

Example Tobi: 30 year old male, 5’8, 196 lbs with an office job.

RMR= 1825 + 100 cal fudge factor (Tobi likes to take the stairs and fidgets)

Total 1925 cal for normal daily activities


Now Tobi is big into crossfit, and he thinks he has a shot at regionals in a few years.  Tobi generally works out at least 1 hour a day at his gym, and on a few days a week he will do multiple sessions.  Tobi spends 10 hours a week working out hard.  So how will this affect his nutrition requirements?

Let’s figure out how much he is burning per hour for a crossfit class.  Most classes are a warm up, strength portion, then WOD.  Check out the following figures.

Warm Up: 50 Cal estimate

Hard Strength Training: 8 Calories/ min (source), 25min Lifting = 200

WOD: 15-20 cal/min (source) , 15 min WOD = 225 – 300

A standard 1 hour class burns approximately 475 – 550cal

*This is a hard class with big compound movements.  Some handstand pushups and GHD’s and easier WODs aren’t going to burn this much, so take this as a high end figure. 


These figures are for a fairly large well muscled man.  A petite woman might be around 300 calories for a pretty standard class.

Many people are surprised that crossfit doesn’t burn more calories, but that’s not really the goal.  If you want to burn the max amount of calories, just run for hours.  I know, yuck right!  Burning calories is a by product of exercise, not an indication that you are getting fitter.

We know that Tobi is burning about 500 calories per session which is an hour, we know that he needs 5000 cal per week over his normal daily expenditure.  So here is Tobi’s daily calories.


RMR = 1825cal, + 100 cal = 1925 cal = 5000 cal per week/ 7 = 2639 cal/day

2639 + fudge factor (200-300cal) = 2900 Cal per Day


This is the exact amount he needs to neither gain or lose weight.  For athletes we need to add a little fudge factor to aid in full recovery between sessions.  For someone like Tobi, I generally like to add in about 200-300 calories.  So Tobi’s daily goal would be about 2900 cal.

You’re probably saying that that’s great Jake, but what the hell should Tobi be eating and why is his name Tobi?  Well we are going to cover that, and I think Tobi with an “i” is funny.

Picking Your Macro’s 

This is where a fair amount of individual differences lie.  Some folks will need more or less of  certain macros, but there are some solid guide lines that we need to make sure we are hitting.

Many people erroneously spend all their time focusing on protein, this is a mistake.  While protein is important, it is only one third of the equation.  We need to fine tune, and adjust all of our macros for optimum performance.  Here are the guidelines for crossfitters.

Protein: 1g per pound of lean mass – 1g per pound of bodyweight

Carbohydrate: 1.5g – 2g per pound of bodyweight

Fat: .5g – 8g per pound of bodyweight


You’ll notice that there are some pretty wide ranges here because there are so many different variables that affect your training.  This brings us to our training nutrition guidelines where we will break down exactly how to plan your personal nutrition plan.

First check out this infographic that shows exactly what Olympic athletes eat.  It’s pretty cool.

The Diet of Champions

From Visually.


Training Nutrition Guidelines

The first area we are going to talk about is carbs.  The consideration for these is your personal tolerance for them.  Generally speaking, the more muscle mass you have the more carbs you can tolerate.

If you’re like me, even looking at carbs causes me to gain weight, so I tend to err on the lower end of the spectrum, but I still eat them.  The rule here is that if you gain fat easily then you can go lower on carbs.

Read this article if you want to see how researchers proved that you can get a 10% increase in WOD performance by only increasing your carb intake.

This is one pit fall for Paleo.  Overall it’s a great diet for folks that only do a few WODs a week, and need to lose some weight.  There just aren’t enough carbs for someone that is really training hard.  The Zone diet can also fall into this same trap.

The best times for you to eat carbs are pre and post workout, as they will be used to fuel your WOD and help you get ready for the next session.  If you plan on multiple sessions a day then you need to refuel with carbs as soon as possible after the first session.  Ideally these carbs should be simple sugars that can be digested quickly, which will refill your glycogen stores, and get you ready for the PM session.

Carbs also have a protein sparing effect when ingested together with protein. This means that you’re protein can go to building muscle tissue and won’t need to also be converted into glycogen.  Eat both together!

Next we’ll discus fat. I’ve found that those that convert carbs to fat easily can generally fill in the calories with fat pretty well.  Again we need to be eating the right amount, not going crazy.

So now that we have some considerations, let’s come up with our macro’s for Tobi.

Tobi’s Macros

Protein = 4 cal/gram, Carbs = 4 cal/gram,  Fat = 9 cal/gram

Protein:  200g = 800cal

Carbs: 300g = 1200cal

Fat: 100g = 900cal

Total Calories = 2900 calories


The next thing we need to talk about is where these calories come from.  There has been some recent research that highlights the fact that it doesn’t really matter where your calories come from.  The energy content is really the same to your body.  Read this article about a professor losing weight on a Twinkie diet .

While I don’t advocate for Twinkie dieting, it’s worth noting that you don’t have to go crazy with all organic, grass fed, shiatsu massaged food.  If you have it in your budget, some of these food items are no doubt more nutrient rich, but I think a lot of this stuff is just clever marketing, and I haven’t really seen a lot of research showing that organic stuff is better.

Remember, there are plenty of organic compounds that will kill you, and there are plenty of man made compounds that are great for you.  Just because you can’t pronounce a chemical doesn’t mean it’s good or bad for you, it means you need to do some research !

Generally speaking, you should have a wide variety of meats, poultry, fish and vegetables.  Carbs from fruit and starches are a good way to go, but don’t be afraid of rice and bread, just keep them to a moderate amount if you are carb sensitive.

Final Thoughts 

We’ve discussed a lot of information so far, and there is a lot of research and experience backing this up, but like I said earlier very little of this is set in stone.

Our example Tobi mathematically now has a diet plan, but if after a few weeks we find he’s losing or gaining too much weight, we will need to adjust.  When making adjustments I think 200-300 calorie adjustments are about right.

The best way to track this is to get My Fitness Pal.  It’s free and it allows you track your caloric intake from any food.  I’ve used it for years, and really had good success with it.  It’s so good that many researchers have their subjects record their food with it.

I will also caution folks not to skimp on the carbs.  Crossfitters have been conditioned to think that they shouldn’t have carbs, which doesn’t make any sense.  If you are working out hard, and not trying to lose weight, you must eat carbs.

This article has been a long one, so I thank you for sticking in there.  If you have any questions or comments leave them below and I’ll get you an answer.  Remember, none of this is rocket science, just basic nutrition.  The success doesn’t come from the science it comes from the consistency.